ADDENDUM TO THE 

TOXICOLOGICAL PROFILE FOR

FORMALDEHYDE

Agency for Toxic Substances and Disease Registry 

Division of Toxicology and Environmental Medicine

Atlanta, GA 30333

October 2010
FORMALDEHYDE ii
FORMALDEHYDE iii

CONTENTS

LIST OF FIGURES ......................................................................................................................................v

LIST OF TABLES.......................................................................................................................................vi

Background Statement................................................................................................................................vii

2. HEALTH EFFECTS................................................................................................................................1

2.2 DISCUSSION OF HEALTH EFFECTS BY ROUTE OF EXPOSURE .....................................................1

2.2.1.2 Systemic Effects..............................................................................................................................4

2.2.1.3 Immunological and Lymphoreticular Effects................................................................................20

2.2.1.4 Neurological Effects .....................................................................................................................27

2.2.1.5 Reproductive Effects.....................................................................................................................30

2.2.1.6 Developmental Effects..................................................................................................................36

2.2.1.7. Genotoxicity..................................................................................................................................38

2.2.1.8 Cancer ...........................................................................................................................................46

2.2.2 Oral Exposure....................................................................................................................................58

2.2.2.2 Systemic Effects............................................................................................................................59

2.2.2.3 Immunological and Lymphoreticular Effects................................................................................63

2.2.2.4 Neurological Effects .....................................................................................................................63

2.2.2.8 Cancer ...........................................................................................................................................63

2.2.3 Dermal Exposure...............................................................................................................................64

2.2.3.3 Immunological and Lymphoreticular Effects................................................................................65

2.3 TOXICOKINETICS ..................................................................................................................................66

2.3.3 Metabolism........................................................................................................................................66

2.3.3.1 Inhalation Exposure ......................................................................................................................66

2.3.5 Physiologically Based Pharmacokinetic (PBPK)/Pharmacodynamic (PD) Models..........................66

2.4 MECHANISMS OF ACTION...................................................................................................................70

2.4.1 Pharmacokinetic Mechanisms...........................................................................................................70

2.4.3 Animal-to-Human Extrapolations .....................................................................................................73

2.5 Relevance to Public Health ........................................................................................................................74

2.6 CHILDREN’S SUSCEPTIBILITY............................................................................................................75

2.7 BIOMARKERS OF EXPOSURE AND EFFECT.....................................................................................76

2.7.1 Biomarkers Used to Identify or Quantify Exposures to Formaldehyde.............................................76

2.7.2 Biomarkers Used to Characterize Effects Caused by Formaldehyde ................................................78

2.8 INTERACTIONS WITH OTHER CHEMICALS .....................................................................................79

2.10 METHODS FOR REDUCING TOXIC EFFECTS ...................................................................................79

2.10.1 Reducing Peak Absorption Following Exposure...............................................................................80

2.10.2 Reducing Body Burden .....................................................................................................................81

2.11 ADEQUACY OF THE DATABASE ........................................................................................................81

2.11.2 Identification of Data Needs..............................................................................................................81

2.11.3 Ongoing Studies................................................................................................................................82

3. CHEMICAL AND PHYSICAL INFORMATION................................................................................83

4. PRODUCTION, IMPORT/EXPORT, USE, AND DISPOSAL............................................................83

4.1 PRODUCTION..........................................................................................................................................83

4.2 IMPORT/EXPORT....................................................................................................................................90

4.3 USE............................................................................................................................................................91

4.4 DISPOSAL.................................................................................................................................................94

5. POTENTIAL FOR HUMAN EXPOSURE ...........................................................................................95

5.1 OVERVIEW ..............................................................................................................................................95

5.2 RELEASES TO THE ENVIRONMENT...................................................................................................95

5.2.1 Air .....................................................................................................................................................96

5.2.2 Water...............................................................................................................................................102

5.2.3 Soil ..................................................................................................................................................102

5.3 ENVIRONMENTAL FATE ....................................................................................................................103
FORMALDEHYDE iv

5.3.2.1 Air...............................................................................................................................................103

5.3.2.3 Sediment and Soil .......................................................................................................................103

5.4 LEVELS MONITORED OR ESTIMATED IN THE ENVIRONMENT................................................104

5.4.1 Air ...................................................................................................................................................104

5.4.2 Water...............................................................................................................................................106

5.4.4 Other Environmental Media ............................................................................................................106

5.5 GENERAL POPULATION AND OCCUPATIONAL EXPOSURE ......................................................107

5.7 POPULATIONS WITH POTENTIALLY HIGH EXPOSURES ............................................................109

5.8.2 Ongoing Studies..............................................................................................................................109

6. ANALYTICAL METHODS................................................................................................................112

6.1 BIOLOGICAL MATERIALS..................................................................................................................112

6.2 ENVIRONMENTAL SAMPLES ............................................................................................................112

6.3 ADEQUACY OF THE DATABASE ......................................................................................................115

6.3.2 Ongoing Studies..............................................................................................................................115

7. REGULATIONS, ADVISORIES, AND GUIDELINES.....................................................................116

8. REFERENCES ....................................................................................................................................123
FORMALDEHYDE v

LIST OF FIGURES

2-1. Health Effects of Breathing Formaldehyde ............................................................................ 2

2-2. Health Effects of Ingesting Formaldehyde............................................................................. 3
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LIST OF TABLES

2-1. Genotoxicity of Formaldehyde In Vivo ................................................................................ 40

2-2. Genotoxicity of Formaldehyde In Vitro ............................................................................... 44

2-3. Human Case Reports—Ingestion of Formalin ..................................................................... 59

4-1. U.S. Formaldehyde Capacity and Production ...................................................................... 85

4-2. Facilities that Produce, Process, or Use Formaldehyde........................................................ 87

4-3. Distribution of Formaldehyde Production According to Uses in the United States............. 93

5-1. Releases to the Environment from Facilities that Produce, Process, or Use 

Formaldehyde ...................................................................................................................... 97

5-2. The Contribution of Various Atmospheric Environments to the Average Exposure to 

Formaldehyde .................................................................................................................... 108

5-3. Ongoing Studies on Formaldehyde .................................................................................... 110

6-1. Analytical Methods for Determining Formaldehyde in Biological Materials.................... 112

6-2. Analytical Methods for Determining Formaldehyde in Environmental Samples.............. 113

6-3. Ongoing Studies on Formaldehyde .................................................................................... 115

7-1. Regulations, Advisories, and Guidelines Applicable to Formaldehyde............................. 118
FORMALDEHYDE vii

ADDENDUM FOR FORMALDEHYDE

Supplement to the 1999 Toxicological Profile for Formaldehyde 

Background Statement

This addendum to the Toxicological Profile for Formaldehyde supplements the profile that was released in 1999. 

Toxicological profiles are developed in response to the Superfund Amendments and Reauthorization Act (SARA) of 

1986, which amended the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 

(CERCLA or Superfund). CERCLA mandates that the Administrator of ATSDR prepare toxicological profiles on 

substances on the CERCLA Priority List of Hazardous Substances and that the profiles be revised “no less often 

than once every three years.” CERCLA further states that the Administrator will “establish and maintain inventory 

of literature, research, and studies on the health effects of toxic substances” [Title 42, Chapter 103, Subchapter I,

§ 9604 (i)(1)(B)].

The purpose of this addendum is to provide to the public and other federal, state, and local agencies a non-peer 

reviewed supplement of the scientific data that were published in the open peer-reviewed literature since the release 

of the profile in 1999. 

Chapter numbers in this addendum coincide with the Toxicological Profile for Formaldehyde (1999). This 

document should be used in conjunction with the profile. It does not replace it.
FORMALDEHYDE 1

2. HEALTH EFFECTS

2.2 DISCUSSION OF HEALTH EFFECTS BY ROUTE OF EXPOSURE

Figure 2-1 illustrates the health effects of breathing formaldehyde in humans and laboratory animals and 

the range of air concentrations at which these effects were seen. Figure 2-2 shows the health effects of 

formaldehyde ingestion in laboratory animals and the dose ranges at which these effects occur. 
FORMALDEHYDE 2

Figure 2-1. Health Effects 

0.1 to 0.5

0.6 to 1.9

2.0 to 5.9

6.0 to 10.9

11 to 50

>50

nasal and eye irritation, neurological 

effectsb, increased risk of asthma 

and/or allergies

change in pulmonary functionc, enhanced 

allergic responses, neurological effectsg

nasal and eye irritation, eczema, change 

in pulmonary functiona 

change in pulmonary functionc, 

neurological effectsg

nasal, eye and throat irritation, eczema or 

skin irritation, change in pulmonary 

functiona

nasal and eye irritation, throat irritation, 

change in pulmonary functionc, 

decreased body weight, enhanced 

allergic responses, neurological effectsg, 

liver effectse, testicular effectsf

nasal, eye, throat and skin irritation, 

headache, nausea, discomfort in 

breathing, cough 

nasal and eye irritation, nasal ulceration, 

change in pulmonary functionc, liver 

effectse, testicular effectsf, nasal tumors, 

reduced survival

nasal and eye irritation, nasal ulceration, 

change in pulmonary functionc, 

neurological effectsd, liver effectse

decreased body weight, decreased fetal 

weight, nasal tumors, reduced survival 

no studies

no studies bloody nasal discharge, pulmonary 

edema

Concentration in Air (ppm) Effects in Humans Effects in Animals

a changes in pulmonary variables from spirometry testing (FEV, FVC)

b decreased performance on short--term memory tests c decrease breathing rate and/or increased airway resistance d listlessness, hunched appearance, uncoordinated movement, ataxia 

e altered serum biochemistry and/or liver histopathology

f

decreased testicular weight, testicular atrophy, altered sperm motility/morphology, decreased serum testosterone, decreased 

diameter of seminiferous tubules

g decreased motor activity, altered open field behavior, impaired learning and memory
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Figure 2-2. Health Effects of Ingesting Formaldehyde

0 to 49

50 to 100

101 to 150

201 to 250

251 to 300

no effects

decreased food intake, decreased body 

weight, gastrointestinal effects a, liver 

effects b, kidney effectsc

decreased food and water intake, 

decreased body weight, gastrointestinal 

effects a, liver effectsb, kidney effectsc

testicular effects d

decreased food and water intake, 

decreased body weight, gastrointestinal 

effects a, liver effectsb, kidney effectsc, 

decreased survival

Dose (mg/kg/day) Effects in Animals

a erosions and ulcers, histopathological changes 

b altered serum biochemistry and histopathology

c occult blood, changes in urine density and volume, kidney weight and histopathology

d altered sperm morphology

151 to 200

no studies
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2.2.1.2 Systemic Effects 

Acute Controlled Exposure Human Studies. Several published studies of respiratory function 

and/or irritation of the nose, eyes, and throat are available involving acute controlled exposure of 

volunteers, generally at formaldehyde concentrations ≤3 ppm. Reviews of these studies include those by 

Arts et al. (2006a, 2006b) and Lang, 2008. Controlled exposure human studies have found that shortterm inhalation exposures to concentrations ranging from 0.4 to 3 ppm can produce symptoms of mild to 

moderate irritation of the eyes, nose, and throat. The odor threshold for formaldehyde in humans has 

been reported to be 1 ppm (Leonardos et al. 1969), but others have noted that it may range as low as 

0.05 ppm (Arts et al. 2006a). 

In a controlled study, Lang et al. (2008) exposed 21 healthy subjects (11 males and 10 females, mean age 

of 26.3 years) to different concentrations of formaldehyde 4 hours/day, 5 days/week for 10 weeks. The 

subjects experienced various exposure conditions, including continuous formaldehyde concentrations of 

0, 0.15, 0.3, and 0.5 ppm in the presence and absence of 12–16 ppm ethyl acetate as a masking agent and 

formaldehyde peak concentrations of 0.6 and 1 ppm (occurring 4 times) accompanying the continuous 

formaldehyde concentrations of 0.3 and 0.5 ppm, respectively. The 2-week exposure sequences were 

randomized with the exposure concentrations, and the daily effect measures were conducted in a doubleblind fashion. Increased blinking frequency and slight to moderate conjunctival redness were observed at 

a continuous formaldehyde concentration of 0.5 ppm, accompanied by peak at a concentration of 1 ppm. 

No treatment-related effects were observed on nasal flow and resistance, pulmonary function, or reaction 

times to visual or acoustic stimuli. The subjective complaints of the volunteers were ocular and nasal 

irritation occurring at lower concentrations (0.3 ppm) of formaldehyde exposure, and were not analogous

to objective test measures of eye and nasal irritations and were believed to be strongly influenced by 

personality factors such as anxiety and smell. Arts et al. (2006a) reviewed respiratory irritation data for 

several sensory irritant chemicals, including formaldehyde. They concluded that objective measures of 
FORMALDEHYDE 5

irritation often differed from subjective measures and were affected by the perception of odor intensity, 

exposure history, and individual bias related to knowledge of chemical effects (Arts et al. 2006a). Xu et 

al. (2002) exposed eight human subjects to 0, 1.65, 2.99, or 4.31 ppm formaldehyde through a pair of 

goggles (eyes-only exposure) for 5 minutes. Each formaldehyde concentration produced an increase in 

eye blinking. This effect was concentration-related and peaked at approximately 1 minute of exposure. 

In a controlled study no statistically significant effects were observed in lung function tests in 10 

volunteers exposed to up to 2 ppm formaldehyde for 3 hours (Kulle et al. 1993). Furthermore, no 

statistically significant exposure-related effects on acute or subacute changes in lung function 

measurements were observed among 15 healthy subjects (Schachter et al. 1986) or 15 mild asthmatics 

(Witek et al. 1987) exposed in environmental chambers to formaldehyde from 0 to 2 ppm for 40 minutes. 

In similar studies, formaldehyde was administered in controlled environments at different concentrations, 

and no significant adverse effects were observed in 10 healthy subjects exposed up to 2 ppm for 3 hours 

(Kulle et al. 1987), or in 21 healthy subjects exposed to 0.5 ppm for 4 hours with a formaldehyde peak

concentration of 1 ppm occurring once per hour (Lang et al. 2008). Similar results were reported by 

Ezratty et al. (2007), where 12 human subjects with allergic asthma exposed to 0 or 0.4 ppm 

formaldehyde for 1 hour showed no asthmatic response. Furthermore, Krakowiak et al. (1998) detected 

no adverse pulmonary effects in 10 formaldehyde-exposed textile or shoe manufacturing workers with 

purported bronchial asthma and 10 non-exposed healthy subjects exposed to 0.4 ppm for 2 hours. 

Acute Occupational Exposure Human Studies. Inconsistent effects have also been found in 

numerous assessments of pulmonary function variables in formaldehyde-exposed workers during 

workday shifts. For example, Bracken et al. (1985) measured no significant changes in pulmonary 

function variables (FVC, FEV1, and FEFR25–75) during a workshift in which 10 laboratory technicians 

were exposed to estimated average formaldehyde concentrations ranging from 0.106±0.02 to 

0.269±0.05 ppm. Akbar-Khanzadeh et al. (1994) found no statistically significant differences in 

workshift changes in pulmonary function variables (FVC, FEV1, FEV3, and FEFR25–75) in a group of 
FORMALDEHYDE 6

34 students exposed for 2-3-hour periods to an estimated time-weighted average (TWA) concentration of 

1.24±0.61 ppm (range 0.07-2.94 ppm) in a gross anatomy laboratory, as compared to a non-exposed 

group of 12 subjects serving as controls. However, the exposed group showed an average 1.2% decline in 

FEV3 during exposure, compared to a 1.3% increase in FEV3 for the controls during a comparable period. 

In another group of 50 students exposed to formaldehyde-containing embalming fluid in a 3-hour gross 

anatomy laboratory and a control group of 36 non-exposed students in a 3-hour physiotherapy laboratory, 

pulmonary function variables increased during the 3-hour periods, but the average increases in FEV1 and 

FEFR25–75 for the exposed group (2.7 and 2.2%, respectively) were statistically significantly less than the 

average increases (5.2 and 9.3%, respectively) for the control group (Akbar-Khanzadeh and Mlynek 

1997). Estimates of breathing zone formaldehyde concentrations in the anatomy laboratory ranged from 

0.3 to 4.45 ppm, with a mean of 1.88±0.96 ppm. In both studies by Akbar-Khanzadeh and colleagues, 

eye and nose irritation were reported by >70% of exposed subjects. Kriebel et al. (2001) evaluated 

pulmonary function and respiratory symptoms in 38 anatomy students (9 men and 29 women, mean age 

24.9 years) exposed to 1.1+0.56 ppm formaldehyde for 2.5 hours/week for 14 weeks. The highest shortterm exposure level was 10.91 ppm for a 12-minute interval. During the first 4 weeks of the exposure 

period, mean PEFR was slightly reduced immediately following a 2.5-hour formaldehyde exposure (-1% 

per ppm, as determined by multivariate modeling). Eye, nose, and throat irritations were the most 

common symptoms reported. The intensity of reported symptoms also declined after 4 weeks, suggesting 

development of respiratory tolerance to formaldehyde exposure. Delfino et al. (2003) conducted a panel 

study of 22 asthmatic children (10–16 years old) living in a Los Angeles community with high traffic 

density. Children recorded daily symptoms and PEFR for 3 months. Formaldehyde concentrations were 

measured at a single central monitoring site. Although formaldehyde concentrations fluctuated only

between 0.004 and 0.01 ppm, there was a significant relationship between daily fluctuations and reported 

symptoms. The adjusted odds ratio (OR) for bothersome or more severe asthma with an inter-quartile 

range (IQR) increase (0.003 ppm) in formaldehyde was 1.37 (95% CI 1.04–1.8), with a 1-day lag. There 

was no relationship with PEFR. A limitation of the study was the use of a central monitoring site as an 
FORMALDEHYDE 7

indicator of exposure. For children, domestic concentrations are likely to be the main predictor of 

personal exposure to formaldehyde. Ambient air fluctuations in formaldehyde may have been an 

indicator of other chemicals (e.g., traffic-related pollutants).

Repeated Exposure Human Studies. Studies of formaldehyde-exposed humans with repeated exposure 

under occupational, or residential conditions provide confirmatory evidence that formaldehyde can be 

irritating to the upper respiratory tract (Kim et al. 1999; Takahashi et al. 2007; Wei et al. 2007). Earlier 

studies provided limited evidence that pulmonary functions may be adversely affected by repeated 

exposure to formaldehyde (Alexandersson and Hedenstierna 1988, 1989; Bracken et al. 1985; Holness 

and Nethercott 1989; Horvath et al. 1988; Khamgaonkar and Fulare 1991; Kriebel et al. 1993; 

Krzyzanowski et al. 1990; Malaka and Kodama 1990). 

Takahashi et al. (2007) surveyed 143 medical students exposed to 2.4±0.49 ppm formaldehyde (1.79–

3.78 ppm) for 15 hours/week for 2 months. Clinical symptoms included skin irritation (27%), eye 

soreness (68%), lacrimation (60%), eye fatigue (45%), rhinorrhea (38%), and throat irritation (43%). 

Students with a history of allergic rhinitis (31 of 143 students) complained of rhinorrhea and sneezing 

more often than students without a history of allergic rhinitis. One hundred sixty seven medical students 

exposed to formaldehyde from 0.16-9.2 ppm (0.194-11.245 mg/m3

) during cadaver dissection practice

revealed clinical symptoms that included eye soreness (92.8 %); lacrimation (74.9 %); headaches (51.5 

%); and rhinorrhea (50.3 %) (Kim et al.1999). Wei et al. (2007) reported similar clinical symptoms in 

medical students exposed to a peak concentration of 0.89 mg/m3 (0.72 ppm) of formaldehyde for 6-8 

hours/day for 3 months. Takigawa et al. (2005) demonstrated that installation of ventilation fans to a 

gross anatomy laboratory reduced the median personal formaldehyde exposure from 3.31 mg/m3 (2.70 

ppm) to 0.875 mg/m3 to (0.715 ppm) and reduced the intensity of skin eczema and eye, nose, and throat 

irritation. Clinical findings of upper respiratory tract inflammation were reported in 12 of 29 (41%) 

workers exposed to a mean formaldehyde concentration of 0.87 mg/m3 (0.71 ppm) -range 0.52–1.56 ppm-
FORMALDEHYDE 8

or for a mean exposure duration of 12.7 years (Lyapina et al. 2004). The clinical observations included 

hypertrophy or atrophy of the upper respiratory mucous membranes, chronic pharyngitis, rhinitis, 

rhinosinusitis, and rhinopharyngitis. A history of frequent viral or bacterial inflammatory relapses of the 

upper respiratory tract was also reported in these formaldehyde-exposed workers. 

Earlier, Holmstrom and Wilhelmsson (1988) examined respiratory symptoms and pathophysiolgical 

effects of workers exposed to formaldehyde and wood dust. Furthermore, Holmstrom et al. (1989)

investigated histological changes in nasal tissue specimens from a group of 70 workers exposed to 

formaldehyde alone, and exposed to formaldehyde in combination with wood dust from a chemical plant 

that produced formaldehyde, and formaldehyde resins for impregnation of paper. Included in this study 

were 100 furniture factory workers working with particle board and glue components and a referent group 

of 36 office workers in the same village as the furniture factories (Holstrom et al. 1989c). The 36 office 

workers are referred to as a referent group, because they received low-level formaldehyde exposures. 

Mean durations of employment in the groups were 10.4 years (standard deviation [SD] 7.3, range 1-

36 years) for the chemical workers, 9.0 years (SD 6.3, range 1–30 years) for the furniture workers, and 

11.4 years (SD 5.4, range 4-18 years) for the referent group. Estimates of personal breathing zone air

concentrations ranged from 0.04 to 0.4 ppm of formaldehyde (median 0.24±0.13 ppm) for the chemical 

workers, from 0.16 to 0.4 ppm (median 0.20±0.04 ppm) for the furniture workers, and from 0.07 to 

0.13 ppm in the late summer for the office workers, with a year-round office worker median reported as 

0.07 ppm with no standard deviation. The mean wood dust concentration in the furniture factory was 

reported to have been between 0.81 ppm and 1.6 ppm (1 and 2 mg/m3

). In the Holmstrom and 

Wilhelmsson (1988) study, three physical examinations were performed on each participant on separate 

days: (1) mucociliary clearance of indocyanine green and spirometry; (2) medical examination including 

rhinomanometry; and (3) olfactory (sensitivity) test using binary pyridine dilutions. There were no 

differences between groups in tobacco usage, and none of the participants were occupationally exposed to 

solvents. The symptoms questionnaire revealed that a significantly greater percentage of formaldehyde-
FORMALDEHYDE 9

exposed workers suffered from nasal discomfort (64 vs 25%; p<0.001); eye discomfort (24 vs 6%; 

p<0.05); lower airway discomfort (44 vs 14%; p<0.01); and frequent headache (24 vs 6%; p<0.05). Other 

specific symptoms (e.g., nasal obstruction, watery discharge) occurred more frequently in the 

formaldehyde-exposed group (p<0.05; data not presented) than the other groups. The latencies for nasal 

and lower airway symptoms in the formaldehyde-exposed group were 4.3 and 3.0 years, respectively.

During time away from work (e.g., weekends and vacations) symptoms improved in approximately 67% 

of the formaldehyde-exposed workers. Mucosal swelling was more pronounced in the formaldehydeexposed group in comparison to referents, as evidenced by a greater improvement in rhinomanometry 

values in response to administration of a decongestant. Mucociliary clearance was pathologically slow in 

20% of formaldehyde-exposed workers, compared to 35% of the referents (p<0.05). In addition,

formaldehyde-exposed workers suffered from a greater loss of smell compared to the referent group

(p<0.01). In spirometric tests, the formaldehyde-exposed group exhibited FVC values that were 

significantly lower than the expected values (4.979 vs. 5.556 L; p<0.001). However, FEV was not 

affected by formaldehyde exposure. The results of rhinomanometry, spirometry, and olfactory tests 

indicated that the workers' symptoms did not become more severe with increasing duration of exposure

(Holmstrom and Wilhelmsson, 1988).

The following studies of baseline pulmonary function variables (e.g., FVC, FEV1, FEFR25–75) have found 

no abnormal average values for groups of workers repeatedly exposed to formaldehyde or no statistically 

significant exposure-related differences compared to referent, non-exposed workers: (1) 10 laboratory 

technicians employed for an average 7.7 years in workplaces with estimated mean concentrations ranging 

from 0.106±0.2 to 0.269±0.05 ppm (Bracken et al. 1985); (2) 109 particleboard workers employed for an 

average 10.3 years (range <1–20 years) in a plant with estimated TWA concentrations ranging from 

0.17 to 2.93 ppm (mean 0.69 ppm) (Horvath et al. 1988; (3) 64 embalmers (embalming for an average of 

10 years) and 12 embalming apprentices (employed <1 year) estimated to have been exposed to 

formaldehyde concentrations ranging from 0.08- 0.81 ppm (mean 0.36±0.19 ppm) (Holness and 
FORMALDEHYDE 10

Nethercott 1989); and (4) 16 health professional working in a pathology laboratory for >4 years 

(formaldehyde concentrations were not reported) (Ostojic et al. 2006). 

Fransman et al. (2003) conducted a study of respiratory symptom prevalence in 112 plywood workers 

employed for an average duration of 4.7±3.5 years. Measured formaldehyde exposure levels ranged from 

0.008- 0.6 ppm (0.01–0.74 mg/m3

). The geometric mean concentration of inhalable dust was 0.57 ppm 

(0.7±1.9 mg/m3

). Personal exposure concentrations of bacterial endotoxin, abietic acid, α-pinene, 

β-pinene, and δ-carene were also measured. Reported attacks of shortness of breath with wheezing in the 

past 12 months were increased in plywood workers employed for >6.5 years (34.2%) compared to the 

general population (15%, n=415) (adjusted OR 2.6, 95% confidence interval [CI] 1.1–5.8). Reports of 

being awakened by shortness of breath were also increased in these workers (23.1%) compared to the 

general population (8.7%) (adjusted OR 3.8, 95% CI 1.4–10). Eleven workers with high exposure to 

formaldehyde reported more respiratory symptoms (36.4% woken with shortness of breath) than workers 

with low exposure (n=38, 7.9%) (adjusted OR 9.5, 95% CI 1.2–74.7). However, these findings should be 

interpreted with caution due to the small number of workers assigned to these exposure categories and the 

potential for exposure misclassification due to the small number of personal exposure measurements 

obtained for analysis (n=22). No clear association between the measured concentrations of inhalable dust 

bacterial endotoxin, abietic acid, α-pinene, β-pinene, and δ-carene and the prevalence of respiratory 

symptoms was found (Fransman et al. 2003). Mean values of FVC, FEV1/FVC, and maximum expiratory 

flow rate were significantly lower in a group of 37 anatomy and histopathology workers compared to

values for a control group of 37 non-exposed workers from the same college (FVC 2.18 vs. 2.63 L; 

FEV1/FVC 0.607 vs. 0.787; flow rate 1.55 vs. 2.71 L/second) (Khamgaonkar and Fulare 1991). 

Employment durations were not reported in this study, but estimated formaldehyde air concentrations 

ranged from 0.036 - 2.27 ppm (mean 1.0±0.55 ppm) in the anatomy and histopathology workplaces 

compared to 0-0.52 ppm (mean 0.1±0.11 ppm) in the control workplaces. The investigators suggested 
FORMALDEHYDE 11

that the apparent bronchoconstrictor effect of formaldehyde was due either to a direct effect of 

formaldehyde, or to a reflex response caused by irritation of the nose and throat.

Similarly, Pourmahabadian et al. (2006) reported that FVC and FEV1 were reduced by 18 and 21%, 

respectively, in 124 pathology laboratory workers exposed to formaldehyde compared to an unexposed 

hospital staff (post-shift measurements). Pre-shift measurements of FVC and FEV1 were also decreased 

by 14 and 16%, respectively. The differences between pre- and post-shift measurements were greatest for 

pathology workers than for the staff working in the surgery and endoscopy departments. Formaldehyde 

exposure concentrations were not directly measured for this study. However, formaldehyde 

measurements from seven other area hospitals suggested that concentrations in pathology laboratories 

were higher than other hospital departments. Formaldehyde-exposed workers reported asthma symptoms 

and signs of eye and nasal irritation (Pourmahabadian et al. 2006). 

Mean baseline PEFR declined by about 2% over a 10-week period in a group of 24 physical therapy 

students who dissected cadavers for 3-hour periods per week (Kriebel et al. 1993). Estimates of breathing 

zone formaldehyde concentrations ranged from 0.49 - 0.93 ppm (geometric mean 0.73±1.22 ppm). PEFR

was the only pulmonary function variable measured in this study, and it was measured before and after 

each exposure period. Post-exposure PEFR means were 1-3% lower than pre-exposure PEFR means 

during the first 4 weeks, but this difference was not apparent during the last 6 weeks. Fourteen weeks 

after the end of the 10-week period, the mean PEFR for the group returned to the pre-exposure baseline 

value. Similar findings were reported in a more recent study of 38 students exposed to 1.1±0.56 ppm 

formaldehyde for 2.5 hours/week for 14 weeks (Kriebel et al. 2001). The highest short-term exposure 

level for this group was 10.91 ppm for a 12-minute interval. During the first 4 weeks of the exposure 

period, mean PEFR was slightly reduced immediately following a 2.5-hour formaldehyde exposure (-1% 

per ppm determined by multivariate modeling). No difference in PEFR was observed during the last 10 

weeks of the exposure period.
FORMALDEHYDE 12

Mild nasal epithelial lesions observed in formaldehyde-exposed workers have been observed consistently 

across four studies (Ballarin et al. 1992; Boysen et al. 1990; Edling et al. 1988; Holmstrom et al. 1989),

and the lesions do not appear to be confounded by exposure to wood dust (see Edling et al. 1988; 

Holmstrom et al. 1989). Furthermore, these studies are consistent with results from animal toxicity, 

pharmacokinetic, and anatomical airflow studies indicating that at concentrations ≤1ppm, inhaled 

formaldehyde gas does not reach lower regions of the respiratory tract.

Franklin et al. (2000) reported that residential formaldehyde concentrations of >0.05 ppm did not affect 

pulmonary function variables (FVC or FEV1) in healthy children (n=224, 6-13 years old). Nitric oxide 

exhalation was increased in children exposed to >0.05 ppm formaldehyde compared to children exposed 

to <0.05 ppm. This effect may represent a subclinical inflammatory response in the airways of healthy 

children. No concentration range or upper concentration limit was provided for exposed children in this 

study.

The formaldehyde/asthma hypothesis was investigated in young children from 6 months to 3 years of age 

in a population-based control study at an Australian hospital (n=88, mean age 25 months) involving agematched controls (n=104). Although the diagnosis of asthma in this age group was difficult, each of the 

cases had an episode of acute wheeze sufficient to be treated at the emergency department of the hospital. 

Passive residential sampling for formaldehyde was performed in both winter and summer months. The 

association between formaldehyde exposure and asthma in children was tested by including formaldehyde 

as a categorical or continuous variable in multivariate linear regression models. The model was adjusted 

for known asthma risk factors and other confounding variables. The investigators concluded that children 

who are exposed to indoor air formaldehyde concentrations > 0.049 ppm (60 μg/m3

) are 39% more likely 

to have an asthmatic attack than children not exposed to such levels (Rumchev et al. 2002). 
FORMALDEHYDE 13

Venn et al. (2003) performed a similar case-control study of 193 children between the ages of 9 and 11

with persistent wheezing, and 223 healthy controls. Indoor air samples were collected in the homes from 

the kitchen, living room and the child’s bedroom. There were no differences in formaldehyde 

concentrations in homes between the cases and controls. The investigators concluded that domestic 

volatile organic compounds are not a primary determinant of risk of severity of childhood wheezing, but 

formaldehyde exposure may enhance the symptoms severity, and the risk of wheezing was increased by

dampness (on a four category scale of % wood moisture equivalent). The investigators also concluded 

that wheezing was more frequent among the cases at night due to formaldehyde exposure and dampness 

with an OR 1.45 (1.06 to 1.98) and 1.97 (1.0 to 3.53), respectively (Venn et al. 2003).

Garrett et al. (1999) conducted a cross-sectional survey of 80 homes in Australia. The survey included a 

total of 148 children, 53 of whom were reported to be asthmatic. The children in this study were between 

7 and 14 years of age. Passive residential sampling for formaldehyde was performed four times between 

March 1994 and February 1995 (median 0.0126 ppm, maximum 0.111 ppm). An association between 

exposure to indoor formaldehyde and atopy was observed. However, no significant increase was 

observed between the adjusted risk of asthma or respiratory symptoms and increasing formaldehyde 

concentration. The authors suggested that low-level exposure to indoor formaldehyde may provide an 

increased risk of allergic sensitization to common aeoroallergens in young children (Garrett et al. 19991). 

In another cross-sectional case-control study, Tavernier et al. (2006) investigated the home environment 

of 105 asthmatic children between 4 and 7 years of age, and 95 healthy controls. There were no 

differences in formaldehyde residential air concentrations between cases and controls. No analyses were 

conducted within the asthmatic group. Furthermore, Jaakkola et al. (2004) reported an association

between the presence of particle board in homes and asthma-like symptoms in children. No 

formaldehyde air levels were reported in this study. 
FORMALDEHYDE 14

Recently, McGwin et al. (2010) conducted a meta-analysis of seven peer reviewed studies that compared 

formaldehyde exposure in children with and without asthma. They calculated summary ORs employing 

either the fixed, or random effects model and found a significant association between formaldehyde 

exposure and childhood asthma. For each 10 μg/m3 unit increase in formaldehyde, the asthma risk was 

1.03 (95% CI: 1.02 – 1.04) by use of the fixed effects model, whereas the random effects model reported 

a higher OR (OR= 1.17; 95% CI: 1.02–1.04). The authors also reported a list of limitations found in their 

analysis of these studies. These limitations included selection bias, self-reported information, seasonal 

variations in formaldehyde measurements in indoor air, and the fact that some studies reported adjusted 

estimates, whereas others did not. However, subject to these limitations, the authors suggested that there 

is a positive association between indoor inhalation of formaldehyde and induction of asthma in children. 

Moreover, they suggested that further epidemiological investigations of the formaldehyde/asthma 

hypothesis in children are necessary (McGwin et al. 2010).

Acute Inhalation Animal Studies. Animal studies have shown evidence and confirmed that the upper 

respiratory tract is a critical target for inhaled formaldehyde and that exposure-response relationships for 

upper respiratory tract irritation and epithelial damage exist in several species. Acute animal studies have 

also shown that inhaled formaldehyde at certain exposure concentrations damages epithelial tissue in 

specific regions of the upper respiratory tract in rats, mice, and monkeys (Ohisuka et al. 2003; Thomas et 

al. 2007) and that formaldehyde is a more potent sensory irritant in mice (Nielsen et al. 1999) than in rats 

(Chang et al. 1983).

Ohtsuka et al. (2003) found strain differences in the upper respiratory toxicity of rats exposed to 15 ppm–

20 ppm formaldehyde 3 hours/day for 5 days. The incidence and severity of clinical signs (i.e., abnormal 

respiration, nasal discharge, and sneezing) and the nature and extent of histopathological changes (i.e., 

degeneration, desquamation, and neutrophil invasion) were greater in F-344 rats than in Brown Norway 

rats. 
FORMALDEHYDE 15

Increased epithelial cell proliferation was observed in the nasal epithelium but not in the lung parenchyma 

of rats exposed to10 ppm of formaldehyde for 3 hours during exercise or at rest (Mautz 2003). In this 

study, formaldehyde exposure also induced degenerative proliferation in the tracheal epithelium during 

exercise. These results indicate that very limited amounts of formaldehyde reach the lungs with exposure 

to 10 ppm (Mautz, 2003). 

Intermediate Inhalation Animal Studies. Results from intermediate-duration inhalation studies 

with rats (Ozen et al. 2003), Rhesus monkeys (Monticello 1989), Cynomolgus monkeys (Rusch et al. 

1983), mice (Maronpot et al. 1986), and hamsters (Rusch et al. 1983) indicate that the nasal epithelium is 

the most sensitive target of inhaled formaldehyde. 

Ozen et al. (2003) exposed groups of male Wistar rats to 0, 5, or 10 ppm formaldehyde 8 hours/day, 

5 days/week for 4 or 13 weeks. Rats from all exposure groups experienced unsteady breathing, increased 

nose cleaning, excessive licking, frequent sneezing, and nasal mucosal hemorrhages. Trace element 

levels of zinc and iron were altered in lung tissue from formaldehyde-exposed rats. However, the 

significance of these changes is not known, because measures of pulmonary function or lung 

histopathology were not evaluated. 

No treatment-related histopathological changes to the lungs or trachea were observed in female C3H/He 

mice exposed to 0.08, 0.4, or 2 ppm formaldehyde 16 hours/day, 5 days/week for 12 weeks (Fujimaki et 

al. 2004, 2005). Similarly, no histopathological changes were observed in male and female Wistar rats 

exposed to 2.6 or 4.6 ppm of formaldehyde 10 minutes/day, 7 days/week for 90 days (Pitten et al. 2000). 

Nasal cavity tissues were not examined in these studies, and clinical signs of nasal or eye irritation were 

not reported.
FORMALDEHYDE 16

No histological evidence of adverse effects on cardiovascular tissues was found in an acute study of rats 

exposed up to 5.4 ppm formaldehyde 2 hours/day for 10 days (Malek et al. 2003c). Gulec et al. (2006b) 

suggested that formaldehyde inhalation may produce oxidative stress in the heart (0, 10, or 20 ppm 

formaldehyde, 8 hours/day, 5 days/week for 4 or 13 weeks). However, increased superoxide dismutase 

activity appears to prevent elevated lipid peroxidation from occurring. 

Hematological Effects. Petushok (2000) found evidence of lipid peroxidation-i.e., increased 

thiobarbituric acid reactive substances and catalase activity-in the blood of rats exposed to 8 ppm (10 

mg/m3 ) of formaldehyde for 7 hours/day for 5 days. No changes in glutathione levels, glutathione 

reductase activity, or glutathione peroxidase activity were observed.

Musculoskeletal Effects. No histopathological changes were reported in skeletal muscle of rats 

exposed to formaldehyde up to 5.4 ppm for 2 hours/day for 10 consecutive days (Malek et al. 2003c). 

Several investigators have studied the potential of formaldehyde to produce oxidative stress in the liver of 

animals (Petushok 2000; Kum et al. 2007; Sogut et al. 2004). Petushok (2000) showed evidence of lipid 

peroxidation (increased thiobarbituric acid reactive substances and catalase activity) in the liver of rats 

exposed to 8 ppm (10 mg/m3

) 7 hours/day for 5 days. Glutathione levels and glutathione reductase 

activity were increased, but the activity of glutathione peroxidase was similar to that of controls. Kum et 

al. (2007) reported no changes in liver weight or liver biochemistry parameters (superoxide dismutase and 

catalase activities and glutathione and malondialdehyde levels) in adult rats exposed to 6 ppm 

formaldehyde 8 hours/day for 6 weeks. An increase in liver weight (18%) and a decrease in liver 

superoxide dismutase activity were observed in 4-week-old rats from this study (6 ppm formaldehyde, 

8 hours/day for 6 weeks). Decreases in absolute liver weight and altered liver biochemistry parameters 

were observed for developing rats under the same exposure conditions. The investigators suggested that 

the decrease in liver weight is likely related to the observed decrease in body weight seen in these groups 

(relative liver weight was not reported). Catalase activity and malondialdehyde levels were increased in 
FORMALDEHYDE 17

prenatally exposed rats. However, glutathione levels were reduced in rats exposed during the postnatal 

period. These results suggested that oxidative stress may result from formaldehyde exposure in the 

developing rat liver. However, no histopathological examination of the liver was performed for this 

study. Sogut et al. (2004) also suggested that hepatic oxidative stress may result from formaldehyde 

inhalation in rats. Glutathione levels were decreased in liver homogenates from rats exposed to 10 or 

20 ppm formaldehyde 8 hours/day, 5 days/week for 4 weeks. Xanthine oxidase activity was also 

decreased, but only at the higher concentration of formaldehyde (20 ppm). Malondialdehyde levels, nitric 

oxide concentrations, and myeloperoxidase activity in rat liver were not altered by formaldehyde 

inhalation for 4 weeks (Sogurt et al. 2004). 

No histological liver changes were found in rats exposed to up to 5.4 ppm, 2 hours/day for 10 days 

(Malek et al. 2003c) or 4.6 ppm, 10 minutes/day, 7 days/weeks for 90 days (Pitten et al. 2000). Mild 

infiltration of mononuclear cells into the portal space, hepatocellular regeneration in the periportal area, 

and dilation and congestion of sinusoids and centrilobular veins were observed in the liver of rats exposed 

to 1.5 ppm formaldehyde for 18 weeks in the use of three different exposure scenarios (4 hours/day for 

4 days/week, 2 hours/day for 4 days/week, or 2 hours/day for 2 days/week) (Fazeli et al. 2006). No 

evidence of necrosis was found. The frequency and daily duration of exposure were not related to the 

nature or severity of histologic changes in the liver. The weight of available evidence suggests that 

airborne formaldehyde may produce toxic effects on the liver only at high concentrations that may exceed 

metabolic and binding capacities in the respiratory tract.

Renal Effects. No evidence from histological examinations, or blood chemistry monitoring for 

formaldehyde-induced kidney effects has been found in acute-or intermediate-duration inhalation studies 

with animals (rats, Rhesus monkeys, or mice) (Malek et al. 2003c; Pitten et al. 2000), or in chronic 

inhalation studies with rats and mice (Kamata et al. 1997; Kerns et al. 1983). Kum et al. (2007) found 

that the serum urea concentration was increased in rats exposed to 6 ppm formaldehyde 8 hours/day for 
FORMALDEHYDE 18

6 weeks, and no changes were observed in serum protein, albumin, or creatinine in comparison to control 

animals. Kidney weight and biochemistry parameters (superoxide dismutase and catalase activities and 

glutathione and malondialdehyde levels) were also similar to control animals (Kum et al. 2007).

Endocrine Effects. No human studies were located in the literature regarding inhalation exposure to 

formaldehyde and adverse endocrine effects. Furthermore, there is no evidence from histological 

examinations, or organ weight measurements for formaldehyde-induced effects on endocrine organs (e.g., 

pancreas, pituitary, adrenals, thyroid) in acute, or intermediate-duration inhalation studies with rats, mice,

or Rhesus monkeys (Appelman et al. 1988; Malek et al. 2003c; Pitten et al. 2000; Woutersen et al. 1987), 

or in chronic inhalation studies with rats or mice (Kamata et al. 1997; Kerns et al. 1983).

Sorg et al. (2001) reported that exposure of rats to 0.7 or 2.4 ppm formaldehyde, 1 hour/day, 5 days/week 

for 4 weeks increased basal corticosterone levels in the serum. Exposure of female mice to 0.08, 0.4, and 

2 ppm formaldehyde, 16 hours/day, 5 days/week for 12 weeks produced increases in the number of 

corticotrophin-releasing hormone-immunoreactive neurons in the hypothalamus. This effect was 

observed at exposure levels of 0.4 and 2 ppm formaldehyde. Similarly, increases in adrenocorticotropin 

hormone-immunoreactive cells in the anterior pituitary gland were observed in mice exposed to 

formaldehyde at 0.08, 0.4, and 2 ppm (Sari et al. 2004). An increase in adrenocorticotropin hormone 

mRNA levels was also seen in the pituitary gland. It was indicated that this upregulation of the 

hypothalamus-pituitary-adrenal pathway is not clearly adverse and may represent an adaptive response to 

formaldehyde exposure. Sari et al. (2004) reported that the upregulation response was impaired in 

allergy-model mice (sensitized with ovalbumin) exposed to 0.4 and 2 ppm. However, the importance of 

this pathway to the overall health status of the animal is unclear.

Dermal Effects. Occupational exposures to formaldehyde have been associated with dermal irritation 

and the diagnosis of allergic contact dermatitis by patch testing. Reported historical percentages of 
FORMALDEHYDE 19

subjects with skin problems showing positive responses to formaldehyde in patch tests performed by 

dermatologists using aqueous solutions with 1 or 2% formaldehyde include 8.1% in Pennsylvania 

between 2004 and 2005 (Anderson et al. 2007), 7.8% in North America between 1992 and 1994 (Marks et 

al. 1995), 1.6% in a 1983–1984 Swedish study (Meding and Swanbeck 1990), 2.6% in a 1988–1989 

European study (Mennè et al. 1994), and 3.7% in a 1990–1994 Polish study (Kjec-Swierczynska 1996).

Takahashi et al. (2007) conducted a prospective study of clinical symptoms and skin test reactions in 

143 medical students exposed to 2.4 ppm+0.49 ppm formaldehyde, 15 hours/week for 2 months. Skin 

irritation was reported in over 25% of students after repeated exposure to formaldehyde. Students with a 

history of atopic dermatitis (22 of 143 students) complained of skin irritation and redness more often than 

students without a history of atopic dermatitis. Positive patch testing was reported for only 2 of 

60 students (3.3%) (1 male with allergic hand dermatitis due to direct contact with a cadaver and 1 female 

with an atopic background and symptoms). Negative patch test findings were also reported for 

58 students similarly exposed to formaldehyde 2–4 years previously. 

 

Body Weight Effects. Body weight effects have not been associated with formaldehyde exposure in 

humans, but exposure-response relationships have been described in animal studies. Body weight 

decreases ≥10% of control values were observed in formaldehyde-exposed animals in the following 

studies: (1) male rats exposed to 2 ppm, 6 hours, 5 days/week for 28 months (Kamata et al. 1997); 

(2) developing female rats exposed to 6 ppm, 8 hours/day for 6 weeks (Kum et al. 2007); (3) male rats 

exposed to 5 or 10 ppm, 8 hours/day, 5 days/week for 4 or 13 weeks (Ozen et al. 2003); (4) male rats 

exposed to 9.9 or 19.9 ppm, 8 hours/day, 5 days/week for 4 or 13 weeks (Ozen et al. 2002); and (5) 

female mice exposed to 5 or 10 ppm, 6 hours/day, 5 days/week for 2 weeks (Jung et al. 2007). No body 

weight effects were observed in rats exposed to formaldehyde up to 5.4 ppm, 2 hours/day for 10 days 

(Malek et al. 2003c) in rats exposed up to 4.6 ppm, 10 minutes/day, 7 days/week for 90 days (Pitten et al. 
FORMALDEHYDE 20

2000) or in mice exposed up to 2 ppm, 16 hours/day, 5 days/week for 12 weeks (Fujimaki et al. 2004, 

2005; Sari et al. 2004).

2.2.1.3 Immunological and Lymphoreticular Effects 

There are only a few recently available case reports of bronchial asthma suggestive of respiratory tract 

sensitization to formaldehyde gas, including a textile worker (Kim et al. 2001). This case of 

formaldehyde-exposed workers displayed marked changes in FEV1 or airflow rates in response to acute 

challenges with formaldehyde gas at exposure levels <3 ppm. Vandenplas et al. (2004) reported a case of 

a persistent asthma following exposure to a high concentration of formaldehyde; the asthma was not 

considered to arise through an immunological mechanism. Inhalation challenge with concentrations up to 

3 ppm did not result in a change in FEV1, and the observed increase in IgE antibodies to formaldehyde 

was transient. Furthermore, 10 formaldehyde-exposed textile or shoe manufacturing workers with 

purported bronchial asthma were challenged with 0.41 ppm formaldehyde for 2 hours and showed no 

changes in FEV1 (Krakowiak et al. 1998).

Several studies have examined serum for the presence of formaldehyde-specific IgE antibodies in groups 

of formaldehyde-exposed humans (Doi et al. 2003; Kim et al. 1999; Wantke et al. 1996a). In general, the 

studies do not provide consistent evidence for a formaldehyde-induced allergic respiratory syndrome, but

they provide suggestive evidence that children may have an increased tendency to develop specific 

antibodies after exposure to low levels of formaldehyde from indoor air (Wantke et al. 1996a). 

Doi et al. (2003) examined the prevalence of IgE specific antibody sensitization to formaldehyde in 

Japanese children with asthma. Low levels of formaldehyde- IgE specific antibody were detected in only 

2 of 150 children (122 children with asthma and 33 nonallergic children). One of these children was 
FORMALDEHYDE 21

reported to have severe asthma and frequent symptoms of mucosal irritation, while the other was reported 

to have mild asthma and only rare symptoms of mucosal irritation. 

Ezratty et al. (2007) evaluated the effects of formaldehyde exposure on allergenic responses in 12 human 

subjects with intermittent asthma and allergy to grass pollen. Subjects were exposed to 0 or 0.4 ppm 

formaldehyde for 1 hour in a double-blind crossover study. Exposures were separated by 2 weeks, and 

the order of exposure to either formaldehyde, or purified air was randomized. Exposure to formaldehyde 

for 1 hour had no effect on FEV1 or PEFR in human subjects with allergic asthma. Formaldehyde 

exposure did not affect the bronchial allergen responses to grass pollen or methacholine provocation. The 

levels of inflammatory markers measured in sputum (differential cell counts, interleukin [IL]-1, IL-4, 

IL-5, IL-8, and IL-10, granulocyte-macrophage colony stimulating factor [GMCSF], monocyte 

chemotactic protein-1 [MCP-1], tumor necrosis factor [TNF]-α, interferon[IFN]-γ, eotaxin-1, and 

eosinophilic cationic protein [ECP] levels) were similar in subjects exposed to either formaldehyde or 

purified air (Ezratty et al. 2007).

Casset et al. (2006) evaluated the effects of acute formaldehyde exposure (0.08 ppm for 30 minutes, 

mouth-breathing only) on the bronchial response to mite allergen in 19 subjects with mild asthma and 

allergic sensitization to house dust mites (confirmed by skin prick testing and IgE-specific antibodies to 

Dermatophagoides pteronyssinus). Formaldehyde exposure did not affect baseline pulmonary function or 

the nonspecific bronchial reactivity to methacholine. The immediate bronchial response to dust mite 

allergen occurred at a lower allergen concentration when subjects were pre-exposed to formaldehyde 

compared to air. The late-phase reaction, expressed as the maximum decrease in FEV1 from baseline, 

was enhanced when subjects were exposed to formaldehyde. ECP concentrations in sputum were higher 

following exposure to formaldehyde than for exposure to air. Although this study suggests that 

formaldehyde could affect allergen responses in sensitized individuals, it is unlikely that low 
FORMALDEHYDE 22

concentrations of formaldehyde would reach the lower airways under conditions where nose-breathing is 

allowed (Casset et al. 2006).

Matsunaga et al. (2008) performed a cross-sectional epidemiology study to evaluate the possible 

relationship between formaldehyde exposure and allergic disorders in 998 pregnant Japanese women. 

Subjects were considered to have asthma, atopic eczema, or allergic rhinitis if they received medical 

treatment for these disorders during the 12 months prior to initiation of the study. Formaldehyde 

exposure determined by passive sampling devices worn for 24 hours was categorized into four groups 

based on the 30th, 60th, and 90th percentile values (<0.018, 0.018–0.027, 0.028–0.046, and >0.047 ppm). 

The prevalence of asthma, atopic eczema, and allergic rhinitis in the study population was 2.1, 5.7, and 

14.0%, respectively. No association was found between formaldehyde exposure and the prevalence of 

asthma or allergic rhinitis. There was a tendency for a positive relationship between the formaldehyde 

concentration and atopic eczema. When the exposure data were categorized into two groups by use of a 

cutoff point at the 90th percentile, formaldehyde concentrations of >0.047 ppm were associated with an 

increased prevalence of atopic eczema in the multivariate model that controls for age, gestation, parity 

family history, cigarette smoking, mold, domestic pets, mite antigen level in house dust, family income, 

education, and season of data collection (adjusted OR 2.25, 95% CI 1.01–5.01).

In another study, Garrett et al. (1999) evaluated the risk of allergy in children exposed to residential 

concentrations of formaldehyde. The authors used a cross-sectional survey of 80 homes in Australia (148 

children, 53 of whom were asthmatic). Passive residential sampling for formaldehyde was performed 4

times between March 1994 and February 1995, and the median level of formaldehyde was 0.0126 ppm,

while the maximum level was 0.111 ppm. Formaldehyde exposure categories were <0.02, 0.02–0.04, and 

>0.04 ppm (<0.02, 0.020–0.050, and >0.050 mg/m3

) on the basis of the highest recorded levels. 

Respiratory questionnaires were completed by parents, and skin-prick testing was performed with 

12 environmental allergens. No significant increase was observed between the adjusted risk of asthma or 
FORMALDEHYDE 23

respiratory symptoms with increasing formaldehyde concentration. A trend was observed between the 

formaldehyde exposure category and the proportion of atopic children. Logistic regression analysis using 

adjustments for parental asthma (i.e., family history) and sex gave an adjusted OR of 1.42 (0.99–2.04) for 

an increase in atopy associated with the highest recorded formaldehyde concentration of 0.02 ppm 

(0.02 mg/m3

). The analysis was not adjusted for passive smoking, presence of pets, nitrogen dioxide 

levels, or airborne fungal spores or dust mites, because these factors did not influence the outcome of the 

analysis and were not considered to be confounding factors. The number of positive skin-prick tests and 

the average size of the allergen wheal were increased in the highest formaldehyde exposure category

>0.04 ppm (>0.050 mg/m3

) compared to the lowest formaldehyde exposure group (> 0.02 ppm 

[<0.02 mg/m3

]).

No histopathological effects on lymphoreticular tissues (e.g., spleen, thymus, lymph nodes) were 

observed in rats exposed up to 5.4 ppm formaldehyde, 2 hours/day for 10 days (Malek et al. 2003c), or in 

rats exposed to up to 15 ppm formaldehyde, 6 hours/day, 5 days/week for 28 months (Kamata et al. 

1997).

Ohtsuka et al. (2003) evaluated the inflammatory response in the nasal mucosa of F-344 and Brown 

Norway rats exposed to 15 to 20 ppm formaldehyde aerosol, 3 hours/day for 5 days. Strain differences 

were observed in clinical signs (abnormal respiration, nasal discharge, and sneezing) and the incidence 

and severity of histopathological effects in the nasal mucosa (degeneration and desquamation of epithelial 

cells with neutrophil invasion). These effects were more pronounced in F-344 rats than in Brown Norway 

rats. The expression levels of T helper cell 1 (Th1)-related cytokines (INF-γ and IL-2) were reduced in 

nasal mucosa of Brown Norway rats, but not of F-344 rats, compared to untreated controls. The 

expression of Th2-related cytokines (IL-4 and IL-5) in the nasal mucosa was not altered by formaldehyde 

treatment in either rat strain. The altered cytokine levels in this study do not clearly explain the strain 

differences in nasal mucosa toxicity, and the biological significance of these changes is unknown.
FORMALDEHYDE 24

Jung et al. (2007) investigated the pulmonary inflammatory response in female mice exposed to 0, 5, or 

10 ppm formaldehyde for 6 hours/day, 5 days/week for 2 weeks, and the authors observed a 10% decrease 

in body weight in mice treated with 5 or 10 ppm. However, lung, liver, kidney, spleen, and thymus 

weights of the treated animals were similar to those of controls. Histopathological analysis of the lung 

tissues demonstrated eosinophils and mononuclear cell infiltration of the alveolar cell walls and alveolar 

spaces in formaldehyde exposed mice. Exposed mice had a higher number of CCR3+ eosinophils in 

bronchoalveolar lavage fluid than control mice and showed upregulated gene expression of 

CC-chemokine receptor-3 (CCR3), eotaxin, intercellular adhesion molecules (ICAM-1), and 

proinflammatory cytokines (IL-1, IL-4, and IL-5) in mouse lung. Formaldehyde exposure also produced 

an increase in the serum levels of IgG1, IgG3, IgA, and IgE compared to controls. Gene expression of 

thioredoxin (TRX), a redox-regulating antioxidant protein, was suppressed in formaldehyde-exposed 

mice, and levels of intracellular reactive oxygen species levels were increased. These results were 

consistent with the observed increase in the number of CCR3+-expressing eosinophils, and the results 

suggest that reactive oxygen species were generated from eosinophils recruited to the inflammatory sites 

of the airways (Jung et al. 2007).

In another study, Franco et al. (2006) examined the pulmonary inflammatory response in rats exposed to 

formaldehyde (concentration not measured) for 90 minutes/day for 4 days. Formaldehyde exposure 

produced an increase in leukocytes in bronchoalveolar lavage fluid, peripheral blood, and spleen, but the 

exposure did not alter cell counts in bone marrow. Formaldehyde also reduced the contractile response to 

methacholine in isolated rat bronchi. Lung histopathology showed mast cell degranulation and neutrophil 

invasion resulting from formaldehyde exposure. Mechanistic experiments suggest that leukocyte 

infiltration and bronchial hyporesponsivness may involve nitric oxide, airway sensory fibers, and mast 

cell mediators. 
FORMALDEHYDE 25

Fujimaki et al. (2004, 2005) evaluated the effect of formaldehyde exposure on allergic inflammatory 

responses in the lung by comparing non-immunized mice to allergy model mice (immunized with 

ovalbumin). Female C3H/He mice were exposed to formaldehyde concentrations of 0, 0.08, 0.4, or 

2 ppm, 16 hours/day, 5 days/week for 12 weeks. Formaldehyde exposure did not alter body weight or 

thymus weight in non-allergy or allergy model female mice. Spleen weight was reduced in nonimmunized mice exposed to 0.4 or 2 ppm formaldehyde, but it was unchanged in allergy-model mice. No 

histopathological evidence of inflammation was noted in the lungs or trachea of formaldehyde-exposed 

mice (nasal tissues were not examined). In non-immunized mice, formaldehyde inhalation did not alter 

the cell profile in bronchoalveolar lavage fluid. The number of macrophages and eosinophils was 

increased in allergy-model mice exposed to 2 ppm compared to allergy model controls. However, the 

level of IL-1β was reduced in these mice. Immunization with ovalbumin increased the production of 

nerve growth factor in bronchoalveolar lavage fluid and plasma, but exposure to 0.08 or 0.4 ppm 

formaldehyde (but not 2 ppm) reduced nerve growth factor levels compared to immunized control mice. 

Formaldehyde exposure did not alter the total number of spleen cells or the number of CD3-positive T 

cells, CD19-positive B cells, or the CD4/CD8 T cell ratio. The spleen cell proliferative response to 

mitogens or ovalbumin was not changed by formaldehyde exposure. An increase in INF-γ production 

was increased in cultured spleen cells from non-immunized mice exposed to 2 ppm formaldehyde for 12 

weeks. Ovalbumin-stimulated monocyte chemo-attractant protein (MCP-1) was increased in allergymodel mice exposed to 0.4 or 2 ppm formaldehyde. Plasma levels of anti-ovalbumin IgG1 and IgG3 

were decreased in mice exposed to 0.4 ppm. Substance P levels in the plasma increased in a dosedependent fashion in non-immunized mice, but not in allergy-model mice. To summarize, alterations in 

some immune parameters were noted for both allergy and non-allergy model mice; however, a clear 

pattern of effects contributing to allergic sensitivity was not found. Some changes in cytokines and 

neuropeptides were noted, but tests of immune function were not performed. No IgE-mediated allergic 

inflammatory response was observed in these studies (Fujimaki et al. 2004, 2005).
FORMALDEHYDE 26

Fujii et al. (2005) also demonstrated that formaldehyde inhalation may alter the intensity of the allergic 

contact hypersensitivity response to other chemicals. The effect of formaldehyde inhalation on the 

contact hypersensitivity of 2,4,6-trinitrochlorobenzene was determined in mice. Mice were sensitized by 

epicutaneous application of 20 μL of 2% 2,4,6-trinitrochlorobenzene on the right earlobe and challenged 

by applying 20 μL of 0.5% 2,4,6-trinitrochlorobenzene on the left earlobe on day 7 only or on days 7, 14, 

21, 28, and 35 (chronic model). Mice were exposed to 0.2 ppm formaldehyde for 4 weeks prior to 

sensitization or during the challenge or elicitation phase. Ear swelling response was measured, and skin 

lesions were excised following sacrifice for histopathological examination. Draining lymph node cells 

were collected and cultured. Surface markers and cytokine production of T cell subsets were assessed. 

Ear swelling was decreased after a 7-day formaldehyde exposure during the challenge or elicitation phase 

followed by a single challenge dose. This was accompanied by a decrease in edema in the subcutaneous 

adipose tissue, an increased percentage of IL-4-producing CD4+ T cells, and a decreased percentage of 

IFN-γ-producing CD8+ T cells. Formaldehyde exposure for 4 weeks prior to sensitization resulted in an 

increased ear swelling response. Formaldehyde exposure also increased ear swelling during the challenge 

phase if the challenge occurred weekly over a 5-week period (chronic model). A decreased percentage of 

CD4+

, CD25, and+ T cells, an increased percentage of CD8+ and T cells, and an increase in the 

accumulation of mast cells in the elicited area of skin were also observed (Fujii et al. 2005).

In a similar study, Sandikci et al. (2007) exposed rats of four different life stages to 0 or 6 ppm 

formaldehyde 8 hours/day for 6 weeks. Life stage groups included prenatal exposure beginning on 

gestational day 1, early postnatal exposure beginning on the first day after birth, 4-week-old rats, and 

adult rats. Rats were sacrificed at 3, 6, 10, and 18 weeks after the exposure period for the prenatal, 

postnatal, 4-week-old, and adult rat groups, respectively. T lymphocytes in the peripheral blood and

bronchus-associated lymphoid tissue were identified by demonstration of alpha-naphthyl acetate esterase 

activity. Formaldehyde exposure increased the proportion of alpha-naphthyl acetate esterase positive 

T cells in peripheral blood regardless of age. These cells were also increased in the bronchus-associated 
FORMALDEHYDE 27

lymphoid tissue in 4-week-old and adult rats. These results suggest that repeated inhalation exposure to 

formaldehyde may alter systemic cellular immunity.

2.2.1.4 Neurological Effects 

Bach et al. (1990) conducted a study to determine if humans reacted acutely to formaldehyde exposure 

and if previous chronic exposure to formaldehyde adversely affected the responses observed in an acute 

formaldehyde challenge. Thirty-two men who worked at local formaldehyde-related factories were 

selected from 108 workers with more than 5 years of occupational exposure, and 29 matched controls 

were randomly selected from a group of 546 males with similar age, education, and smoking habits. Both 

groups were exposed to formaldehyde at concentrations of 0, 0.12, 0.32, or 0.98 ppm for 5.5 hours in a 

controlled atmospheric environment. The subjects underwent a series of performance tests during the 

exposure period; the tests were designed to access the subject’s distractibility, short-term memory, and 

capability to understand and perform certain tasks. Headaches and physical tiredness occurred more often 

in the controls than in the workers previously exposed to formaldehyde. In both the occupationally 

exposed and the non-exposed subjects, decreased performances in several tests were statistically 

significant, and they correlated with increasing acute exposure concentrations of formaldehyde. The 

occupationally exposed subjects showed significantly decreased performance, as compared to nonexposed subjects, only in a digit span test, but not in variables for a graphic continuous line test, an 

addition test, or a digit symbol test. The authors demonstrated that under controlled environmental 

conditions, exposure to formaldehyde at concentrations of 0.32 ppm and 0.98 ppm may cause acute CNS 

effects (Bach et al., 1990). 

Neurobehavioral effects, including altered motor activity and impaired learning and memory, have been 

noted in animal studies following acute- (Lu et al. 2008; Malek et al. 2003a, 2003b, 2003c, 2004; Morgan 

et al. 1986; Usanmaz et al. 2002; Wood and Coleman 1995) and intermediate-duration (Pitten et al. 2000; 
FORMALDEHYDE 28

Usanmaz et al. 2002) exposure to formaldehyde. No histopathological alterations in the brain or spinal 

cord were found in these studies. Alterations in brain structure were observed in neonatal rats exposed to 

formaldehyde during the first 30 days after birth (Aslan et al. 2006; Sarsilmaz et al. 2007). These studies 

are discussed in Section 2.2.1.6. 

Open field behavior was evaluated in rats exposed to 0, 0.1, 0.5, or 5 ppm formaldehyde for 2 hours 

(Malek et al. 2003b). Rats were exposed to 0, 1, 2.5, or 5 ppm for 2 hours (Malek et al. 2003a), and male 

mice were exposed to 0, 0.1 1, 2, 3, or 5.2 ppm for 2 hours (Malek et al. 2004). These acute 

formaldehyde exposures resulted in a decrease in spontaneous motor activity and changes to some 

exploratory behaviors (i.e., sniffing, rearing) 2 hours after the end of exposures in rats and mice. Some of 

the exploratory behavioral parameters remained altered 24 hours after the end of the exposure (Malek et 

al. 2003a, 2004). Kun Ming male mice exposed to formaldehyde at 0, 0.81, or 2.4 ppm for 6 hours/day 

for 7 days and trained for 30 minutes in a Morris water maze following exposure showed a significant 

decrease in maze performance (increased escape latency and decrease spatial memory) in the 2.4 ppm 

formaldehyde-exposed group, as compared to the control group (Lu et al. 2008). Moreover, oxidative 

stress on the brains of the mice assessed by glutathione and super dismutase changes and increased 

expression of genes associated with learning and memory processes of animals were also observed in the 

2.4 ppm exposure group.

Usanmaz et al. (2002) evaluated the neurotoxicity of acute- and intermediate-duration formaldehyde 

exposures in mice. Mice were exposed to formaldehyde concentrations of 1.8, 2, 3.2, 4.5, 6.4, 7.8, 9.7, 

and 14.8 ppm for 3 hours (1-day exposure), 2 ppm for up to 3 weeks (3 hours/day, 5 days/week), or 

3.2 ppm for up to 2 weeks (3 hours/day, 5 days/week). Spontaneous motor activity was reduced by a 

single 3-hour exposure to formaldehyde at concentrations >1.8 ppm and by repeated exposure to 2 ppm 

for 3 weeks or 3.2 ppm for 2 weeks. The wet-dog shake, a pro-convulsive behavior, was increased at 

concentrations of 1.8, 3.2, and 6.4 ppm for a 3-hour exposure, but the same was not observed at higher 
FORMALDEHYDE 29

acute concentrations or following repeated exposure to 2 ppm for 3 weeks or 3.2 ppm for 2 weeks. 

Pentylenetetrazole-induced seizures were more severe in mice exposed to 1.8 ppm formaldehyde for 

3 hours, as compared to controls. No change in seizure parameters was seen following a 3-hour exposure 

to 6.4 ppm, and a decrease in the incidence of seizures was observed at 14.8 ppm, compared to controls. 

Repeated exposure to formaldehyde did not alter the pentylenetetrazole-induced seizure response in mice

(Usanmaz et al. 2002).

Malek et al. (2003c), using a water maze study design, evaluated the effect of acute formaldehyde 

inhalation on learning and memory in rats. Rats were exposed to 0, 0.1, 0.5, or 5.4 ppm formaldehyde 

2 hours/day for 10 days. A pre-trial period occurred 2 days prior to exposure, when rats were placed in 

the water labyrinth and manually assisted with learning the swimming route to the finish. Animals were 

tested in the water labyrinth each day during the 10-day exposure period (2 hours after exposure). 

Control rats required increasingly shorter swimming times to reach the finish over the 10-day course of 

the experiment. In male rats, the mean swimming time was increased in rats exposed to 0.5 or 5.4 ppm 

formaldehyde, while the error frequency was increased in all formaldehyde treatment groups (0.1, 0.5, or 

5.4 ppm) compared to controls. The mean swimming time was also increased in female rats exposed to 

formaldehyde at 0.5 or 5.4 ppm. However, female rats exposed to 0.1 ppm of formaldehyde showed 

faster swimming times than control rats on several days during the exposure period. The error frequency 

in female rats was increased in all formaldehyde-exposed groups, as compared to controls. No 

histopathological alterations were observed in the heart, thymus, pancreas, liver, kidney, skeletal muscle, 

or spleen. Focal microatelectasis (absence of gas from part or all of the lungs due to failure of expansion 

and resorption) of the lungs (i.e., changes to alveolar structure) was noted in 20-30% of rats from both 

control and formaldehyde-treatment groups (Malek et al. 2003c).

In another study, Pitten et al. (2000) evaluated maze performance in rats exposed to 0, 2.6, or 4.6 ppm 

formaldehyde 10 minutes/day, 7 days/week for 90 days. Maze performance was evaluated every 10th day 
FORMALDEHYDE 30

during the 90-day exposure period and a 30-day post-exposure period. Rats from both formaldehyde 

exposed groups made more errors in maze performance during the exposure period than control rats. No 

difference in maze performance was seen among treatment groups by 4 weeks after cessation of exposure. 

The time required to find food in the maze was longer for rats in both formaldehyde-exposed groups 

during exposure, as compared to control rats. No alterations in general locomotion were observed, and no 

histopathological changes were noted in the liver, trachea, lungs, kidney, heart, spleen, pancreas, testicles, 

cortex, brainstem, cerebellum, or spinal cord (Pitten et al. 2000).

2.2.1.5 Reproductive Effects 

Several comprehensive reviews have concluded that formaldehyde does not produce significant 

reproductive and developmental toxicity. In a review of available reproductive and developmental 

toxicity data for humans and laboratory animals, the World Health Organization (WHO) concluded, 

“There is no convincing evidence that formaldehyde is a teratogen in either animals or human beings. 

Formaldehyde has not produced any adverse effects on reproduction in test animals or human beings”

(WHO 1989). IARC (2006) reached a similar conclusion in a more recent review. Reports of higher 

rates of spontaneous abortion in female occupational workers were characterized as inconsistent, and 

effects on pregnancy and fetal development in animals were not seen at exposures below maternally toxic 

concentrations. Collins et al. (2001) performed a review of the reproductive and developmental toxicity 

data for formaldehyde in animals. They concluded that animal studies demonstrated that formaldehyde is 

unlikely to reach the reproductive system at concentrations sufficient to cause damage due to rapid 

biotransformation of formaldehyde by the respiratory tract (Collins et al. 2001). In addition, human 

studies were considered to be limited by study design flaws and reporting and publication bias. 

Taskinen et al. (1999) performed a retrospective study of time to pregnancy in 699 female wood workers 

from Finland who had given birth between 1985 and 1995. A questionnaire was used to obtain 
FORMALDEHYDE 31

information on exposure, pregnancy history, time-to-pregnancy, and potential confounders. Daily 

formaldehyde exposure concentrations were estimated for each person based on the results of the 

questionnaire and industrial hygiene measurements from the workplace. The three formaldehyde 

exposure categories were determined with mean measured concentrations of 0.07, 0.14, and 0.33 ppm for 

the low, medium, and high categories, respectively. The highest formaldehyde exposure category was 

associated with delayed conception, as measured by an adjusted fecundability density ratio 

(FDR, ratio of average incidence densities of pregnancies for exposed women, compared to 

unexposed women, adjusted for confounding factors) (FDR= 0.64; 95% : CI 0.43–0.92, p=0.02, 

n=39). Further analyses of this group indicated that the use of gloves was an important 

protective factor to dermal exposure to formaldehyde. In fact, women in the high exposure 

group who did not wear gloves had a significantly lower FDR (0.51; 95% CI: 0.28–0.92, n=17),

compared to the unexposed formaldehyde group. Instead, women in the high exposure group 

who used gloves had a non-significant decrease of FDR (0.79; 95% CI: 0.47–1.23). These 

results suggest that dermal exposure to formaldehyde plays a significant role in the potential 

effects on female fertility. Exposure to organic solvents, dusts, and wood dusts were not 

associated with prolonged time to pregnancy (FDR values for exposure categories did not differ from 

unity). It was suggested that formaldehyde exposure may also be related to the risk of spontaneous 

abortion; however, a dose-response relationship for this effect was not apparent. Exposure to high 

concentrations of formaldehyde was associated with increased risk of endometriosis (OR= 4.5; 95% : CI 

1.0–20.0). The authors concluded that a woman’s occupational exposure to formaldehyde has an adverse 

effect on fertility (Taskinen et al. 1999). However, the findings of this study may have several 

limitations-for example, the small number of women in the high formaldehyde exposure group (n=39), 

the fact that exposure to organic solvents was not associated with FDR, and importantly, the finding that 

dermal exposure is suggested to play a significant role in reduced fertility outcome , however,the dose 

absorbed by the dermal exposure route was not estimated. 
FORMALDEHYDE 32

Saillenfait et al. (1989) examined the effects of maternal exposure to inhaled formaldehyde on embryonic 

and fetal toxicity in Sprague-Dawley rats. Groups of 25 dams were exposed to 0, 5, 10, 20, and 40 ppm 

formaldehyde in inhalation chambers on gestational days 6-20. Dams were weighed on gestational

days 0, 6, and 21, and they were randomly assigned to experimental groups so that their body weights on 

gestational days 0 and 6 were similar to those of dams in different dose groups. All dams survived the 

experiment, and on gestational day 21, dams were sacrificed, and their uteri were excised and examined. 

Maternal weight gain, percentage of pregnancy, litter sex ratio, fetal mortality, fetal weight, cleft palate 

malformation, and alterations of soft and skeletal tissues were assessed. Dams exposed to 40 ppm 

formaldehyde had a 51% reduction in weight gain in comparison to controls (p<0.01), but the former 

showed no other clear or overt signs of toxicity. The authors observed no significant differences between 

treatment groups in the incidences of pregnancies, number of implantations, or resorptions, numbers of 

dead, or live fetuses, fetal sex ratios, or the incidences of external, visceral, or skeletal abnormalities. 

Fetal body weights of male offspring from dams exposed to 20 ppm formaldehyde were 5% lower than

those of controls (p<0.05). Furthermore, fetal body weights of male and female offspring from dams 

exposed to 40 ppm formaldehyde (p<0.01) were about 21% lower than those of offspring of controls. 

Therefore, maternal exposure to formaldehyde at 40 ppm for 6 hours/day during gestational days 6–

20 was not teratogenic nor embryotoxic, but exposue at 20 ppm was slightly fetotoxic, as indicated by 

lower fetal body weights (Saillenfait et al., 1989). 

Senichenkova (1991) examined the embryotoxic effect and fetal and juvenile offspring development from 

mongrel female white rat dams exposed to 0 or 0.4 ppm formaldehyde for 4 hours/day on gestational days 

1-19. The results showed that prenatal exposure to formaldehyde does not affect the embryonic mortality 

and does not decrease the crown-tail (craniocaudal) lengths or the weights of embryos. However, 

examination of internal organs of the prenatal formaldehyde-exposed group revealed decreased fetal 

hyoid ossification and increased incidence of total anomalies, with absence of testes as the predominant 
FORMALDEHYDE 33

anomaly (Senichenkova 1991). Senichenkova (1991) also examined the postnatal behavior of offspring 

after prenatal exposure to formaldehyde. The authors observed a significant increase in motor activity and 

exploratory activity in the formaldehyde-exposed group, as manifested by increased numbers of squares 

visited and increased frequency of rearings on postnatal days 2 and 3 in comparison to controls. 

In a similar study of pregnant mongrel female mice exposed to 0 or 0.4 ppm formaldehyde for 4 

hours/day on gestational days 1-19, decreased fetal hyoid ossification and increased incidence of total 

anomalies, with absence of testes as the predominant anomaly, were found in the formaldehyde-exposed 

group (Senichenkova and Chebotar 1996). These investigators observed that when maternal iron 

deficiency anemia was induced in pregnant mongrel mice, the embryo toxic effect of environmental 

xenobiotics studied was significantly increased (Senichenkova and Chebotar 1996). 

Kitaev et al. (1984) exposed mature female Wistar rats to formaldehyde at concentrations of 0, 0.4, or 0.8 

ppm for 4 hours/day, 5 days/week for 123 days. The female rats were mated with male rats on day 120 of

exposure and embryos were removed on day 2 or 3 of gestation. The dams exposed to 0.8 ppm had a 

significant increase in embryo degeneration on the 3rd day. The dams exposed to 0.8 ppm of 

formaldehyde revealed an increase in follicle stimulating hormone (FSH) concentrations in blood samples 

in comparison to controls. The duration of the estrus cycle in dams was not affected by prolonged 

formaldehyde exposure, nor was the weight of the uterus in animals exposed to 0.4 ppm. Initially, these 

authors observed an increase in the weight of the ovaries at the lower dose, but when the animals were 

exposed to formaldehyde at 0.8 ppm, the weight of the ovaries fell below that of the control animals. The 

authors suggested that the increase in ovary weight at exposure to 0.4 ppm corresponded to the increase in 

blood LH and progesterone levels (Kitaev et al. 1984).

In a study of humans, Maroziene and Grazuleviciene (2002) conducted a population-based, crosssectional study in Lithuania to evaluate the relationship between ambient air pollution and the occurrence 
FORMALDEHYDE 34

of low birth weight and pre-term delivery. The study findings related to low birth weight are presented in 

Section 2.2.1.6. The study included all singleton newborns born in 1998 in the City of Kaunas (n=3,988). 

Maternal characteristics were obtained from the Lithuanian National Birth Register, and residential 

concentrations of formaldehyde were estimated from data collected at 12 community monitoring stations. 

The mean formaldehyde concentration during the study period was 2.6 ppb, SD=1.9 ppb (3.14 μg/m3

SD=2.36 μg/m3

). Exposure concentrations were grouped into three categories, and the exposure variable 

was applied as both categorical and continuous parameters through use of multivariate logistic regression. 

No significant association was observed between formaldehyde exposure and premature birth (Marzoiene 

and Grazuleviciene, 2002).

Collins et al. (2001) performed a meta-analysis of eight studies that evaluated spontaneous abortions

related to formaldehyde exposure. Inconsistent findings were reported in the original studies, and the 

meta-analysis was adjusted for reporting and publication bias. The meta-analysis concluded that there 

was no evidence of increased risk of spontaneous abortions among workers exposed to formaldehyde 

(meta-relative risk=0.7, 95% CI 0.5–1.0) (Collins et al, 2001).

Zhou et al. (2006) evaluated the testicular toxicity of formaldehyde in male rats exposed to 0 or 8 ppm 

formaldehyde, 12 hours/day for 2 weeks. Formaldehyde exposure produced a decrease in testicular 

weight and histopathological changes, including atrophy of the seminiferous tubules, a decrease in 

spermatogenic cells, azoospermic lumina, disintegration of seminiferous epithelial cells, which were shed 

into the lumina, and edematous interstitial tissue with vascular dilation and hyperemia. Formaldehyde 

exposure also produced a decrease in sperm motility and an increase in the percentage of abnormal sperm. 

The activities of glutathione peroxidase and superoxidase dismutase and the level of testicular glutathione 

were decreased, while malondialdehyde levels were increased in formaldehyde-exposed rats compared to

controls. Administration of 30 mg/kg/day vitamin E during the formaldehyde exposure period prevented 
FORMALDEHYDE 35

the biochemical changes and the histopathological and sperm motility/morphology changes induced by 

formaldehyde in male rats (Zhou et al. 2006). 

Similar results were reported by Ozen et al. (2002), who observed decreased testicular weight in rats 

exposed to 0, 9.9, or 19.9 ppm (0, 12.2, or 24.4 mg/m3

) formaldehyde 8 hours/day, 5 days/week for 4 or 

13 weeks. This decrease in testicular weight may be related to overall growth retardation, because 

decreases in body weight gain (>10%) were seen at both formaldehyde concentrations after 4 and 

13 weeks of exposure. Altered concentrations of trace metals were found in the testes of formaldehydeexposed rats (decreased zinc and copper, increased iron). However, the relevance of these changes is 

unclear, because no further evaluation of testicular structure or function was performed in this study.

In another study, Ozen et al. (2002) examined male reproductive effects in rats exposed to 0, 5 ppm, or 

10 ppm formaldehyde, 8 hours/day, 5 days/week for 91 days. Serum testosterone levels and the diameters 

of seminiferous tubules were reduced in both exposure groups compared to controls. Immunoreactive 

heat shock protein 70 was detected in the spermatogonia of formaldehyde exposed rats (5 and 10 ppm), 

but not in control rats. The spermatocytes and spermatids located in the adluminal portion of the 

seminiferous epithelium showed high-density immunohistochemical staining for heat shock protein 70 in 

formaldehyde-exposed rats (5 and 10 ppm) and low density staining in control rats. Survival was not 

affected by formaldehyde exposure in this study. However, formaldehyde-exposed rats experienced 

decreased food and water consumption, unsteady breathing, increased nose cleaning, excessive licking, 

frequent sneezing, and nasal mucosal hemorrhages (Ozen et al. 2005).

Adult male Wistar rats exposed to formaldehyde at concentrations of 10 or 20 ppm, 8 hours/day, 

5 days/week for 4 weeks were found to have concentration-related reduced body weight gains and 

decreased Leydig cell quantities in comparison to control animals (Sarsilmaz et al. 1999). Leydig cells 

were examined for histological changes. The percentage of normal Leydig cells was decreased in both 
FORMALDEHYDE 36

formaldehyde exposed groups compared to controls. The histological changes consisted of nuclear 

damage to the Leydig cells (Sarsilmaz et al. 1999).

2.2.1.6 Developmental Effects 

Maroziene and Grazuleviciene (2002) conducted a population-based cross-sectional study in Lithuania to 

evaluate the relationship between ambient air pollution and the occurrence of low birth weight and preterm delivery. The findings related to pre-term delivery are presented above in Section 2.2.1.5. The 

study included all singleton newborns born in 1998 in the City of Kaunas (n=3,988). Maternal 

characteristics were obtained from the Lithuanian National Birth Register, and residential concentrations 

of formaldehyde were estimated from data collected at 12 community monitoring stations. The mean 

formaldehyde concentration during the study period was 2.6 ppb, SD=1.9 ppb (3.14 μg/m3

) (SD=2.36 

μg/m3

). Exposure concentrations were grouped into three categories, and the exposure variable was 

applied as both categorical and continuous parameters by use of multivariate logistic regression. The 

crude and adjusted ORs for low birth weight increased with formaldehyde exposure. After adjustment for 

low birth weight risk factors (maternal age, marital status, education, season of birth, parental smoking), 

the risk of low birth weight remained increased for the medium (OR 1.86, 95% CI 1.10–3.16) and high 

(OR 1.84, 95% CI 1.12–3.03) formaldehyde exposure categories (concentrations for categories were not 

specified). Further adjustment for gestational age slightly increased the OR. However, the estimate 

remained statistically significant only for the high exposure group (OR 2.09, 95% CI 1.03–4.26)

(Maroziene and Grazuleviciene 2002). 

Kum et al. (2007) evaluated the potential for liver toxicity in female rats exposed to 0 or 6 ppm 

formaldehyde 8 hours/day for 6 weeks beginning on gestation day 1 or post-parturition day 1. Body 

weight and liver weight were decreased in rats exposed to 6 ppm formaldehyde during the prenatal or 

early postnatal periods. Catalase activity and malondialdehyde levels in the liver were increased 
FORMALDEHYDE 37

following prenatal exposure to formaldehyde. Glutathione levels were decreased in the early postnatal 

exposure group. Sandikci et al. (2007) used the same study design to evaluate immune system effects in 

rats exposed during the prenatal, or the early postnatal periods. Exposure to 6 ppm formaldehyde 

increased the proportion of α-naphthyl acetate esterase positive T cells in peripheral blood, suggesting 

that systemic cellular immunity may be affected in developing rats. A similar response was seen in young 

(4-week-old) and adult rats. 

The results of studies in neonatal rats have suggested that exposure to formaldehyde can affect brain 

development (Aslan et al. 2006; Sarsilmaz et al. 2007). Aslan et al. (2006) showed alterations in volume 

and cell number of the hippocampal formation of the brain in neonatal male rats exposed to 6 or 12 ppm 

formaldehyde, 6 hours/day, 5 days/week for the first 30 days of life. The brains of rats were examined 

immediately following the exposure period or 60 days later. The morphology of granule cells in the 

dentate gyrus was not altered by formaldehyde treatment. However, the volume of the dentate gyrus was 

increased in both formaldehyde-exposed groups of 30-day-old rats compared to controls. The low 

concentration of formaldehyde also produced an increase in the dentate gyrus volume in 90-day-old rats 

compared to the controls or the high concentration group. A volume reduction in the granule cell layer 

was seen in the high concentration group at 90 days, as compared to rats examined at 30 days. There was 

no effect of formaldehyde treatment on granule cell number immediately following exposure; however, 

exposure to the high concentration resulted in a decrease in the granule cell number 60 days later, as

compared to controls and the low concentration group (Aslan et al. 2006).

Sarsilmaz et al. (2007) demonstrated similar effects in the cornu ammonis region of the hippocampus 

following exposure of neonatal rats to 6 or 12 ppm formaldehyde for 6 hours/day, 5 days/week for the 

first 30 days of life. The brains of rats were examined immediately following the exposure period or 

60 days later. Formaldehyde exposure did not alter the appearance of pyramidal cells in the 

hippocampus. There were concentration-related volume changes in the cornu ammonis and the whole 
FORMALDEHYDE 38

hemisphere of the brain. Immediately following the exposure period, the low concentration of 

formaldehyde increased the cornu ammonis volume, while the high concentration decreased the cornu 

ammonis volume. Both low and high concentrations reduced the whole hemisphere volume immediately 

following the exposure period, but they increased the whole hemisphere volume 60 days later, as

compared to controls. Rats in the high exposure group had fewer pyramidal cells than rats from the low 

exposure group or controls at 30 or 90 days after birth.

Songur et al. (2005) demonstrated that formaldehyde exposure alters trace element levels in the neonatal 

rat lung following exposure to 6 ppm or 12 ppm formaldehyde 6 hours/day, 5 days/week for 30 days 

beginning the first day after birth. Superoxide dismutase activity and copper and iron levels were 

reduced, while zinc levels were increased in lung samples from neonatal rats exposed to formaldehyde. 

These changes were observed immediately following the exposure period and 30 days later. Survival was 

not affected by formaldehyde exposure in neonatal rats. However, food and water consumption and body 

weight measurements were reduced during the exposure period compared to controls. Clinical signs of 

toxicity included sneezing, dyspnea, polypnea, increased nose cleaning, excessive licking, blinking of the 

eyes, and nasal bleeding. At the end of the 30-day post-exposure period, body weights were similar to

those of controls (Songur et al. 2005).

2.2.1.7. Genotoxicity

In vivo Exposure Studies. Results from human in-vivo exposure genotoxicity studies are mixed (Table 2-

1). Several human occupational exposure studies have described increased sister chromatid exchange 

(SCEs) in lymphocytes (Shaham et al. 2002; Ye et al. 2005), while a shorter-term exposure (8 weeks) 

study of anatomy students did not report exposure-related increased SCEs in lymphocytes (Ying et al.

1999). With the exception of one short-term (10-day, 4 hours/day) experimental exposure study (Speit et 

al. 2007a), all other human occupational exposure studies have reported an increased frequency of 
FORMALDEHYDE 39

micronuclei in nasal mucosa (Burgaz et al. 2001; Ye et al. 2005), buccal mucosa (Burgaz et al. 2002), and 

peripheral lymphocyte cells (Orsiere et al. 2006; Sari-Minodier et al. 2001) in exposed workers compared 

to controls. In other studies of formaldehyde workers, no evidence was found of DNA damage (Orsiere 

et al. 2006) or changes in DNA-repair enzyme activity (Schlink et al. 1999) in lymphocytes. 
FORMALDEHYDE 40

Table 2-1. Genotoxicity of Formaldehyde In Vivo

Species (test system) End point Results Reference

Mammalian cells:

Human (peripheral 

lymphocytes)

30 medical students 

<1 ppm

15 months 

Chromosomal aberrations – Vasudeva and Anand 1996

Human (peripheral 

lymphocytes)

18 workers (16 control 

subjects) 

TWA=0.985 mg/m3

mean=8.6 years 

Sister chromatid exchange + Ye et al. 2005

Human (peripheral 

lymphocytes)

23 students (preexposure control)

TWA=0.508 mg/m3

8 weeks (3 hours x 

3 times/week) 

Sister chromatid exchange – Ying et al. 1999

Human (peripheral 

lymphocytes)

90 pathology workers 

(52 controls subjects) 

unspecified 

concentrations

mean=15.4 years 

Sister chromatid exchange + Shaham et al. 2002

Human (nasal mucosa)

18 workers (16 control 

subjects) 

TWA=0.985 mg/m3

mean=8.6 years 

Micronucleus increase + Ye et al. 2005
FORMALDEHYDE 41

Table 2-1. Genotoxicity of Formaldehyde In Vivo

Species (test system) End point Results Reference

Human (peripheral 

lymphocytes)

59 laboratory workers 

with 0.5–34 years of 

previous 

exposure (37 control 

subjects) 

2.0 ppm for 15 minutes 

or 0.1 ppm for 8 hours 

micronucleus increase + Orsiere et al. 2006

Human (buccal mucosa)

10 days (4 hours/day)

experimental exposure 

0.15–0.5 ppm with 

4 peaks of 1.0 ppm for 

15 minutes each

Micronucleus increase – Speit et al. 2007a

Human (peripheral 

lymphocytes)

10 occupationally 

exposed 

women (27 control 

subjects)

unspecified 

concentrations; 

mean=9 years 

Micronucleus increase; 

chromosome aberrations

+ Sari-Minodier et al. 2001

Human (nasal mucosa)

23 laboratory workers 

(25 control subjects) 

2–4 ppm; 

mean=5.06 years

Micronucleus increase + Burgaz et al. 2001

Human (buccal mucosa)

(18 control subjects)

Group I: 22 shoe 

workers 

TWA=11.39–58.07 ppm 

Mean=7.68 years

Group II: 28 pathology 

workers 

TWA=2–4 ppm

mean=4.70 years

Micronucleus increase + Burgaz et al. 2002
FORMALDEHYDE 42

Table 2-1. Genotoxicity of Formaldehyde In Vivo

Species (test system) End point Results Reference

Human (peripheral 

lymphocytes)

59 laboratory workers 

with 0.5–34 years of 

previous exposure 

(37 control subjects) 

2.0 ppm for 15 minutes 

or 0.1 ppm for 8 hours

DNA damage – Orsiere et al. 2006

Human (embalming student 

exposure/peripheral 

lymphocytes)

DNA-repair enzyme activity – Schlink et al. 1999

Rat (lung cells) DNA damage + Sul et al. 2007

– = negative result; + = positive result 
FORMALDEHYDE 43

In other mammalian in-vivo studies, inhalation exposure to formaldehyde has been found to increase 

DNA-protein cross links in the monkey respiratory tract (Casanova et al. 1991) and rat nasal mucosal 

cells following 6-hour exposures. Acute inhalation exposure (6 hours) to formaldehyde was also found to 

induce chromosomal aberrations in pulmonary lavage cells in rats (Dallas et al. 1992) and spleen 

lymphocytes in mice. Inhalation exposure to formaldehyde in rats caused increased DNA damage in lung 

cells following a 2-week exposure (Sul et al. 2007) and p53 suppressor gene mutations in nasal cells after 

2 years of exposure (Recio et al. 1992). Other reports present negative findings for chromosomal 

aberrations in the bone marrow after a 6-hour inhalation exposure to formaldehyde (Dallas et al. 1992) 

and for chromosomal aberrations, mitotic activity, and SCEs in lymphocytes of rats exposed for 5 days 

(6 hours/day). In-vivo formaldehyde exposure resulted in mortality and sterility and caused lethal 

mutations in Drosophila melanogaster, (Valencia, et al. 1989 and Woodruff et al. 1985). 

In vitro Exposure Studies. As summarized in Table 2-2, formaldehyde has been found to be 

mutagenic in Salmonella typhimurium in most studies without metabolic activation, but not mutagenic in 

a few other studies. 
FORMALDEHYDE 44

Table 2-2. Genotoxicity of Formaldehyde In Vitro

Results

Species (test system) End point

With 

activation

Without 

activation Reference

Human (peripheral blood 

lymphocytes)

Micronuclei No data + Iarmarcovai et al. 2007

Human (leukocytes) DNA damage No data + Frenzilli et al. 2000

Human (blood cultures) DNA protein cross 

links; sister 

chromatid 

exchange

No data + Schmid and Speit 2007

Human (blood cultures) Micronuclei No data – Schmid and Speit 2007

Chinese hamster (V79 cell 

HPRT locus culture)

Sister chromatid 

exchange; DNA 

protein cross links

No data + Merk and Speit 1999

Chinese hamster (V79 cell 

HPRT locus culture)

Mutations No data – Merk and Speit 1999

Chinese hamster (V79 cell 

culture)

Sister chromatid 

exchange; DNA 

protein cross links; 

micronuclei

No data + Merk and Speit 1998

Chinese hamster (V79 cell 

HPRT locus culture)

Mutations No data – Merk and Speit 1998

Chinese hamster (V79 cell 

culture)

DNA strand 

breaks

No data – Speit et al. 2007b

Chinese hamster (V79 cell 

culture)

Sister chromatid 

exchange; DNA 

protein cross links; 

micronuclei

No data + Speit et al. 2007b

Syrian hamster embryo cells Sister chromatid 

exchange

No data + Miyachi and Tsutsui 2005

Non-mammalian cells:

Neurospora crassa Mutation No data (+) de Serres and Brockman 

1999

a

Test compound was formalin.

– = negative result; + = positive result; (+) = weakly positive; DNA = deoxyribonucleic acid
FORMALDEHYDE 45

A number of human cell lines have been tested, with formaldehyde giving positive results without 

metabolic activation, resulting in mutations, DNA damage, DNA-protein cross links, increased 

micronuclei, chromosomal aberrations, and SCEs (Emri et al. 2004; Frenzilli et al. 2000; Iarmarcovai et 

al. 2007; Schmid and Speit 2007; Shaham et al. 2003; see Table 2-2). Using a sensitive technique to 

detect total DNA-protein cross links, Shaham et al. (1996) reported that human white blood cells showed 

increasing quantities of DNA-protein cross links when cultured in media with increasing formaldehyde 

concentrations and that a small group of formaldehyde-exposed persons had a significantly greater mean 

amount of DNA-protein cross links in their white blood cells than did a group of non-exposed persons. 

Although DNA-protein cross links are known to be formed by other agents, such as ionizing radiation and 

alkylating agents, Shaham et al. (1996) suggested that levels of DNA-protein cross links in white blood 

cells may provide an indicator of formaldehyde-induced tissue damage and a biomarker of occupational 

exposure to formaldehyde. Statistically significant higher levels of DNA-protein cross links in 

formaldehyde-exposed workers compared to unexposed workers (p<0.01) were later reported in an 

extending study (Shaham et al. 2003). The authors examined peripheral blood lymphocytes of 186 

workers exposed to formaldehyde and in 213 unexposed workers for DNA-protein cross links as well as 

p53 protein. Pantropic (wild type + mutant) p53 >150 pg/ml was higher in exposed workers with DNAprotein cross links above the median (median DNA-protein cross links >0.187). The adjusted OR to have 

pantropic p53 150 pg/mL in workers with DNA-protein cross links above the median was 2.5 (95% CI 

1.2–5.4). The adjusted OR was still significant when stratified by gender in the female group (OR 2.8; 

95% CI 1.1–7.1), but not significant in the male group (OR 1.9; 95% CI 0.5–7.2). 

Formaldehyde Genotoxicity Conclusions. In summary, the majority of tests show that 

formaldehyde in vivo and in vitro exposure can induce genotoxic effects in various organisms and cell 

types. The weight of evidence indicates that formaldehyde itself (not a metabolite) is capable of directly 

reacting with DNA and producing genotoxic effects in portal-of-entry tissues, especially when 

biotransformation capacities are exceeded. More extensive evaluations of the genotoxic potential of 
FORMALDEHYDE 46

formaldehyde are available in IARC (2006) and WHO (1989). Environment Canada/Health Canada

(2001) and WHO (2002) concluded that overall, formaldehyde is weakly genotoxic, with effects most 

likely to be observed in vivo in cells from tissues or organs with which the aldehyde comes into first 

contact.

2.2.1.8 Cancer 

Human Studies Overview. The finding of nasal tumors in rodents exposed to high levels of airborne 

formaldehyde led to a concern about cancer effects in occupationally exposed workers. There are now 

more than 60 epidemiology studies examining the potential for occupational formaldehyde exposure to 

cause cancer in humans. The studies include cohort mortality studies of formaldehyde-exposed industrial 

workers, cohort mortality studies of formaldehyde-exposed professionals or medical specialists, and casecontrol studies that looked for associations between occupational exposure to formaldehyde and cancers 

of the nose, pharynx, or lung. More recent reviews have been published by Duhayon et al. (2008), 

Golden et al. (2006), IARC (2006), and NTP (2005). In addition, several meta-analyses of the data have 

been published (Bosetti et al. 2008; Collins et al. 1997; Luce et al. 2002; Partanen 1993). 

Although some of the epidemiological studies have found some evidence for extra-respiratory site cancers 

in groups of formaldehyde-exposed workers, the data are not consistent across studies, and adjustment for 

potential confounding cancer risk factors has not often been possible. IARC (2006) concluded that while 

a number of studies have found associations between formaldehyde exposure and cancer at other sites,

including the oral cavity, oro- and hypopharynx, pancreas, larynx, lung, and brain, the overall evidence in 

humans does not support a causal role for formaldehyde in these cancers. 

Increased incidences of leukemia rates have been reported in some studies of anatomists, pathologists, 

and embalmers (Blair et al. 1990; Hauptman et al. 2009), and such incidences have also been observed in 
FORMALDEHYDE 47

cohort studies of industrial workers. Two updated large industrial studies showed an association between 

some measures of formaldehyde exposure and relative risk from leukemia (Hauptmann et al. 2003; 

Pinkerton et al. 2004). However, another large industrial follow-up study did not find any association

between exposure to formaldehyde and leukemia (Coggon et al. 2003). In addition, a follow-up of the 

Hauptmann et al. (2003) cohort study revealed that whereas a statistically significant association between 

death from leukemia and peak exposure to formaldehyde remained, the overall association of 

formaldehyde exposure with leukemia had diminished with the additional 10 years of follow-up (Freeman 

et al. 2009). The authors noted that although this decline over time may suggest that the previous results 

could be due to chance, the largest risks occurred closer in time to relevant exposure, a fact that is 

consistent with known leukemogenic agents. A re-analysis of the Hauptmann et al. (2003) data by Marsh 

and Youk (2004) did not support a causal association between formaldehyde exposure and mortality from 

leukemia. External comparisons provided by Marsh and Youk (2004) suggested that elevated risks 

occurred because slight to moderate excesses in mortality were compared to statistically significant 

baseline category deficits in deaths. Collins and Lineker (2004) conducted a meta-analysis of 18 

epidemiology studies of formaldehyde exposed workers reporting rates of leukemia development. These 

investigators did not find any firm support to establish a relationship between formaldehyde exposure and

risk of leukemia (Collins and Lineker 2004). Several studies have examined the biological plausibility of 

formaldehyde-induced leukemia, and have concluded that there is inadequate biological evidence to 

support a possible mechanism of action for hypothesis (Cole and Axten 2004; Golden et al. 2006; Heck 

and Casanova 2004). In contrast to the results of these studies, IARC (2009) concluded that “there is 

sufficient evidence for a causal association of formaldehyde with leukaemia.” 

Many reviewers have agreed that cancer of the respiratory tract, particularly the upper respiratory tract, is 

more biologically plausible than formaldehyde-induced cancer at distant sites (NTP 2010). This is 

probably based on the reactivity of formaldehyde, the capacity of tissues to bio-transform formaldehyde, 

and the results from chronic rodent inhalation studies showing that formaldehyde-induced non-neoplastic 
FORMALDEHYDE 48

and neoplastic effects are restricted to the upper respiratory tract with exposures to concentrations <5-

10 ppm. Accordingly, the reviews and meta-analyses of the human data have focused primarily on the 

findings for respiratory cancer deaths in occupationally exposed humans. 

The following six mortality studies of cohorts of formaldehyde exposed industrial workers are included in 

recent reviews and the meta-analyses: (1) 26,561 former U.S. workers involved in formaldehyde 

production, resin making, and several other activities using formaldehyde (Hauptmann et al. 2004; Marsh 

and Youk 2005; Marsh et al. 2007a); (2) 7,660 workers in six British plants using formaldehyde (Coggon 

et al. 2003); (3) 11,030 workers in three U.S. garment facilities (Pinkerton et al. 2004); (4) 1,332 Italian 

workers involved in resin making (Bertazzi et al. 1986, 1989); (5) 3,929 foundry workers exposed to 

formaldehyde (Andjelkovich et al. 1994, 1995); and (6) 7,345 workers in a Connecticut chemical plant 

that included some of the workers from the Blair et al. (1986) study (Marsh et al. 2002, 2007b). 

In the industrial worker cohort studies, the range of standardized mortality ratios (SMR) relevant to 

exposure to airborne formaldehyde were as follows (a zero reflects a finding of no deaths from the subject 

cancer): 

lung cancer: 0.9 -0.4 (lung cancer deaths were reported in each cohort); 

nasopharyngeal cancer: 0-4.04 (only the Blair et al. [1986, 1990], Hauptmann et al. [2004] cohort 

had nasopharyngeal cancer deaths: eight observed versus two expected);

nasal cancer: 0-1.9 (Andjelkovich et al. [1994, 1995]; Bertazzi et al. [1986, 1989]; Stayner et al. 

1988, however, did not report nasal cancer deaths); and 

buccal cavity and/or pharynx cancer: 0.95–1.69 (only Bertazzi et al. [1986, 1989] did not report 

buccal cavity and/or pharynx cancer). 

Meta-analyses performed by use of human occupational studies have arrived at different conclusions 

regarding the association between formaldehyde exposure and respiratory tract cancer (Bosetti et al. 2008;

Luce et al. 2002). In both analyses, aggregate relative risks for lung cancer deaths calculated for 
FORMALDEHYDE 49

formaldehyde-exposed medical and non-medical professionals were at or below those expected. 

Aggregate relative risks for lung cancer in industrial worker studies showed a small excess relative risk 

(1.1) in both analyses, but no evidence for an exposure-related increase in relative risk in a comparison of

the “low/medium” relative risks (1.2) with those of the “substantial” exposure class (1.0 or 1.1). Small 

excess aggregate relative risks for occupationally exposed workers in all of the studies existed for cancer 

of the nose and nasal sinuses (1.1 [95% CI, 0.8–1.4], Blair et al. 1990; 1.1 [95% CI, 0.8–1.5], Partanen 

1993), and cancer of the nasopharynx (1.2 [95% CI, 0.8–1.7], Blair et al. 1990) and 2.0 [95% CI, 1.4–

2.90], Partanen 1993). Relative risks for both types of cancer increased with increasing exposure 

intensity. The meta-analyses by Collins et al. (1997) and Bosetti et al. (2008) arrived at the conflicting 

conclusion that the available studies do not support a causal relationship between formaldehyde exposure 

and nasopharyngeal cancer. Collins et al. (1997) analyzed data from essentially the same case-control 

studies as Blair et al. (1990) and Partanen (1993), but the authors included a few cohort mortality studies 

that were not available or were included in the earlier meta-analyses (e.g., Andjelkovich et al. 1994, 1995; 

Gardner et al. 1993). Collins et al. (1997) noted that nasopharyngeal cancer rates were elevated in a 

minority of the available studies, that most studies did not find any nasopharyngeal cancers, and that 

many studies did not report on nasopharyngeal cancer. Unlike the calculation techniques used in the 

previous meta-analyses, a calculational technique was used to adjust for underreporting of expected 

mortality rates in the calculation of “weighted meta-relative risks”. Meta-relative risks (with 95% CIs) 

for nasopharyngeal cancer were 1.0 (0.5–1.8) for the 14 cohort studies included in the analysis, 1.2 (0.4–

2.5) for the six industrial worker cohort studies, and 1.3 (0.9–2.1) for the seven case-control studies. 

Collins et al. (1997) concluded from their review of the available studies that exposure estimates for the 

case-control studies were both lower and less certain than exposures in the industrial worker cohort 

studies and that their analysis does not support an exposure-response relationship between formaldehyde 

and nasopharyngeal cancer.
FORMALDEHYDE 50

Bosetti et al. (2008) pooled the results of epidemiology studies published through February 2007, 

including 30 publications describing seven cohorts of industrial workers and nine cohorts of professionals 

exposed to formaldehyde. Nine deaths from nasopharyngeal cancer in three cohorts of industry workers 

gave a pooled relative risk of 1.33 (95% CI 0.61–2.53), a relative risk that declined to 0.49 after excluding 

six cases from one U.S. plant. Pooled relative risk values for cancers of the lung, sinus and nasal cavity, 

oral cavity and pharynx, brain, lymphatic and hematopoietic systems, and leukemia were not elevated in 

industrial workers (pooled SMR and relative risk values <1.1). In professionals exposed to formaldehyde, 

pooled relative risk values for brain cancer, lymphatic and hematopoietic cancers, and leukemia were 1.56 

(95% CI 1.24–1.96), 1.31 (95% CL 1.16–1.48), and 1.39 (95% CI 1.03–1.79), respectively. Bosetti et al. 

(2008) concluded that the meta-analysis showed no appreciable excess risk for oral and pharyngeal, 

sinonasal, or lung cancer. The non-significant increase in relative risk from nasopharyngeal cancer was 

attributed to a cluster of deaths at a single U.S. formaldehyde related plant. Brain and lymphohematopoietic cancers were slightly elevated in professionals exposed to formaldehyde, but the cancers were 

not increased in industrial workers, suggesting that lifestyle or other occupational characteristics of 

pathologists, anatomists, and embalmers may play a role in the observed excess risk for these cancers

(Bosetti et al. 2008).

Luce et al. (2002) performed a pooled analysis of 12 case-control studies of sinonasal cancer in seven 

countries. Occupational exposures to formaldehyde, silica dust, textile dust, coal dust, flour dust, 

asbestos, and human-made vitreous fibers were assessed by use of a job-exposure matrix. The metaanalysis included 195 cases of adenocarcinoma, 432 cases of squamous cell carcinoma, and 3,136 

controls. Odds ratios calculated by unconditional logistic regression were adjusted for age, study, wood 

dust, and leather dust. A significantly increased risk of adenocarcinoma was suggested for males (91 

exposed cases, OR 3.0, 95% CI 1.5–5.7) and females (5 exposed cases, OR 6.2, 95% CI 2.0–19.7). There 

was significant heterogeneity in the findings for men, with a significantly better fit observed for the 

regression model that included interaction terms between exposure effects and study. A review of this 
FORMALDEHYDE 51

study by IARC (2006) concluded that adjustment for extensive heterogeneity in this model may have led 

to inappropriately narrow confidence limits, because random effects are not accounted for. IARC (2006) 

also indicated that a residual confounding by wood dust was possible in this study, despite attempts to 

control for it, due to the high correlation between exposure to wood dust and formaldehyde and the strong 

association between adenocarcinoma formation and wood dust exposure. IARC (2006, 2009) concluded 

that “there is only limited epidemiological evidence that formaldehyde causes sinonasal cancer in 

humans”.

Recent reviews of the available epidemiology studies arrive at differing conclusions. NTP (2005) 

indicated that formaldehyde is reasonably anticipated to be a human carcinogen. IARC (2006) concluded, 

“[the] results of the study of industrial workers in the U.S., supported by largely positive findings from 

other studies, provided sufficient epidemiological evidence that formaldehyde causes nasopharyngeal 

cancer in humans”. IARC’s overall evaluation that formaldehyde is carcinogenic to humans (Group 1) 

was based on specific evaluations that there is sufficient evidence in both humans and experimental 

animals for the carcinogenicity of formaldehyde (IARC 2006). Duhayon et al. (2008) concluded that 

“human studies fail to raise a convincing conclusion concerning the carcinogenicity of formaldehyde and 

are not helpful to delineate a possible dose-response relationship”. Earlier, EPA (1991) classified 

formaldehyde in Group B1 a probable human carcinogen, based on an evaluation of limited human 

evidence and sufficient laboratory animal evidence. However, this assessment has not been updated to 

consider more recent epidemiological data. Environment Canada/Health Canada (2001) and WHO

(2002) concluded that there is little evidence of a causal association between exposure to formaldehyde 

and lung cancer, but the data for nasal and nasopharyngeal cancer are less clear. Case-control studies 

demonstrating increases in cancers of the nasal or nasopharyngeal cavities fulfil, at least in part, 

traditional criteria of causality. However, excesses of cancers of the nasal or nasopharyngeal cavities 

have not been observed consistently in cohort studies. An evaluation of the mode of carcinogenic action 

for inhaled formaldehyde was proposed by Environment Canada/Health Canada (2001) and WHO (2002). 
FORMALDEHYDE 52

The sustained increase in epithelial cell regenerative proliferation resulting from cytotoxicity is 

considered a requisite precursor in the mode of induction of nasal tumors in rats. Mutation for which the 

formation of DNA-protein crosslinks serves as a marker of potential may also contribute to the 

carcinogenicity of the compound in the nasal cavity of rats. The hypothesized mode of induction of 

formaldehyde-induced tumors was determined to satisfy several criteria for weight of evidence (i.e., 

consistency, concordance of exposure-response relationships across intermediate end points, and 

biological plausibility and coherence of the database) and was considered likely relevant to humans, at 

least qualitatively.

Cohort Mortality Studies. Marsh and Youk (2005) performed a re-evaluation of the mortality risks from 

nasopharyngeal cancer observed in Hauptmann et al. (2004). Because 6 of the 10 reported cases of 

nasopharyngeal cancers occurred at a single manufacturing plant located in Connecticut, the re-analysis 

calculated U.S. and local county (regional) SMRs and internal cohort relative risk values. A significant 

excess was observed in the regional SMR for the Connecticut manufacturing plant, where six cases of 

nasopharyngeal cancers were observed (SMR 10.32, 95% CI 3.79–22.47). However, the mortality from 

nasopharyngeal cancers was lower than expected for the other nine manufacturing plants combined (i.e., 

SMR<1.00). The relative risk analysis demonstrated that the exposure-response relationship was driven 

by the nasopharyngeal cancer risk at the Connecticut plant and the highest peak exposure category 

(≥4 ppm). For the remaining nine plants, the relative risk values were below 1 for the highest peak 

exposure categories, and no evidence of an exposure response relationship was observed. Marsh et al. 

(2007a) also performed an interaction assessment to determine the appropriateness of the model chosen 

by Hauptmann et al. (2004) and a sensitivity analysis to explore the degree of instability in the risk 

assessments for nasopharyngeal cances in relation to the highest peak exposure. The results of the 

interaction assessment suggested that the model used by Hauptmann et al. (2004) did not account for the 

important interaction between plant group and the exposure variable that may prohibit the generalization 

of formaldehyde effects within and beyond the cohort. In addition, the sensitivity analysis demonstrated 
FORMALDEHYDE 53

considerable uncertainty in the risk estimates for nasopharyngeal cancer, especially at the Connecticut

plant (Marsh et al 2007a).

Several additional studies have been performed to further investigate the cancer mortality in the cohort of 

7,345 former workers employed at the Wallingford, Connecticut manufacturing plant (Marsh et al. 1994, 

1996, 2002, 2007b). In the most recent follow-up study of this population, “vital status for 98% of the 

cohort and cause of death for 95% of 2,872 deaths were determined through 2003” (Marsh et al. 2007). 

Lagged and un-lagged exposure measures were determined from reconstructed worker exposures. Marsh 

et al. (2007) “observed no new deaths for nasopharyngeal cancers, and only one new death for all other 

pharyngeal cancer deaths, which yielded SMRs of 4.43 (95% CI 1.78–9.13; 7 deaths) and 1.71 (95% CI 

1.01–2.72, 16 deaths), respectively.” After the use of interaction models for this nested case-control study 

for this cohort, the results showed that nasopharyngeal and all other pharyngeal cancers were not elevated 

in subjects exposed to formaldehyde alone (Marsh et al. 2007). These authors indicated that risks of 

nasopharyngeal cancers increased in areas where people worked in silver smithing facilities, including 

brass plating and other jobs related to silver or brass (Marsh et al. 2007). Five of seven cases of 

nasopharyngeal cancer worked in silver smithing or other metal working industries, while this was 

relatively rare in the remaining study population (OR 7.311, 95% CI 1.08–82.1). Other metal work was 

also associated with a moderate increase in the relative risk of all other pharyngeal cancers (OR 1.4, 95% 

CI 0.31–5.1). These findings suggested that secondary work in the metal industry may have contributed

to the elevated findings of nasopharyngeal cancers at the Wallingford, Connecticut plant compared to the 

other nine manufacturing plants (Marsh et al. 2007).

For the final analysis, death certificates were available for a large percentage (92%) of the identified 

decedents. A trained nosologist coded the underlying cause of death for all death certificates, using the 

coding rules in effect at the time of each death. Therefore, the assignment of the cause of death should 

have been comparable to that used for the standard (comparison) population. The analysis controlled for 
FORMALDEHYDE 54

potential confounding effects from age, race, sex, and calendar year. Several weaknesses of this study 

were also noted. In general, PMR studies have a relatively weak design compared to other types of 

studies. The analysis included only those deaths reported to the Bureau of Funeral Directing and 

Embalming, and the completeness of this reporting is not known. The authors indicate that deaths at ages 

>65 years were substantially under-reported. Consequently, the causes of death in the analysis could have 

differed systematically from the causes found in the total population of deceased embalmers (e.g., for 

chronic conditions that led to death at older ages). The total U.S. population was used as the external 

comparison population, even though rates from New York State would probably be stable enough to 

provide expected values. Possible regional differences in cancer incidence (rather than occupational 

exposures) could have affected the observed pattern of mortality excesses and deficits. Study weaknesses 

included that cancer deaths are often reported inaccurately on death certificates. Exposure levels for 

formaldehyde were unknown, and no analyses that combine the white and black decedents (with 

appropriate adjustment) were presented, even though there were similarities in the pattern of excess 

deaths. A combined analysis presumably would have greater statistical power. Lastly, the expected 

number of deaths for nasal cancer, which was an end point of particular interest, was only 0.7, so that the 

study had low statistical power to detect an excess of this cancer.

Pinkerton et al. (2004) extended the follow up of vital status for the garment workers cohort (Stayner et 

al. 1985a, 1985b, 1988) for an additional 16 years (to 1998). Mortality from all causes and all cancers 

was less than expected, compared to U.S. mortality rates (SMRs <1). Mortality from buccal cavity 

cancer, which was elevated in the original study, was only slightly elevated in the follow-up study (four 

deaths, SMR 1.33, 95% CI 0.36–3.41). No nasal or nasopharyngeal cancers were found, although the 

study had limited statistical power to detect an excess for rare cancers. Mortality from cancer of the 

trachea, bronchus, and lung was not increased (147 deaths, SMR 0.98, 95% CI 0.82–1.15). Excess 

mortality from leukemia and myeloid leukemia was observed, with mortality from myeloid leukemia 

highest in workers exposed for ≥10 years, with ≥20 years since the first exposure (eight deaths, SMR 
FORMALDEHYDE 55

2.55, 95% CI 1.1–5.03). Coggon et al. (2003) followed the British chemical worker cohort (Acheson et 

al. 1984; Gardner et al. 1993) for an additional 11 years through 2000. Mortality from all cancers was 

slightly elevated (1,511 deaths, SMR 1.1, 95% CI 1.04–1.16) compared to the national population. 

Mortality from lung cancer was increased in men exposed to the highest concentration of formaldehyde 

(>2 ppm) (272 deaths, SMR 1.58, 95% CI 1.4–1.78). The increase in lung cancer mortality remained 

elevated after adjustment for local geographic variations in mortality (SMR 1.28, 95% CI 1.13–1.44). 

Two deaths from sinonasal cancer (2.3 expected) and one death from nasopharyngeal cancer (2.0 

expected) were observed. Mortality from brain cancer and leukemia were lower than expected (SMRs

<1) for the entire cohort and among the highest exposure group.

A statistically significant excess in mortality from respiratory system cancer was observed in the whole 

cohort compared to national data (874 deaths, SMR 1.16, 95% CI 1.08–1.24) (Marsh et al. 2001). The 

analysis was based on 630 cases (96% were carcinoma of the trachea bronchus or lung) and 570 controls. 

Exposure to formaldehyde was estimated through use of industrial hygiene data and a job-exposure 

matrix. The conditional logistic regression analysis that was adjusted for smoking did not demonstrate 

any clear exposure-response trend with cumulative (<2 ppm-years) or average concentration of 

formaldehyde exposure (<0.14 ppm) (Youk et al. 2001). Adjustment of the regression model for 

exposure to respirable particles and smoking provided suggestive evidence that increased risk of mortality 

from respiratory track cancer may be associated with the highest average intensity of formaldehyde 

exposure (Stone et al. 2001). Cumulative exposure to formaldehyde was not associated with respiratory 

tract cancer risk in this model.

Armstrong et al. (2000) interviewed 282 Chinese residents of Malaysia (195 males, 87 females) who had 

a confirmed diagnosis of nasopharyngeal carcinoma and an equal number of age- and gender-matched 

controls. Occupational history, diet, alcohol consumption, and tobacco use were determined. Univariate 

and multivariate methods were used to evaluate exposure to 20 kinds of workplace substances, solar and 
FORMALDEHYDE 56

industrial heat, and cigarette smoke. Formaldehyde exposure was determined by industrial hygiene 

investigation and use of a job-exposure matrix. Only 9.9% of cases and 8.2% of controls were exposed to 

formaldehyde. The adjusted ORs (adjusted for smoking and diet) were <1 for any versus no occupational 

exposure to formaldehyde and for a 10-fold increase in exposure hours. No association was observed 

between formaldehyde exposure and nasopharyngeal cancer (Armstrong et al. 2000).

Hildesheim et al. (2001) performed a case-control study of nasopharyngeal cancer diagnosed at two 

hospitals in Taiwan (375 cases, 325 age- and gender-matched controls). Occupational history for cases 

and controls was obtained by personal interview, and formaldehyde exposure was estimated by industrial 

hygiene investigation and use of a job-exposure matrix. Information was also collected regarding 

potential confounding factors, such as cigarette smoking and diet. Blood samples were collected and 

analyzed for antigen class I/II genotype, polymorphism in cytochrome P450 2E1 genotype, and antiEpstein Barr virus (EBV) antibodies known to be associated with nasopharyngeal cancer. Individuals 

exposed to formaldehyde for >10 years had a relative risk of 1.6 (95% CI 0.91–2.9), which was increased 

when the analysis was restricted to individuals who were seropositive for EBV (relative risk 2.7, 

95% CI 1.2–5.9). However, no exposure-response relationship was observed with increasing duration of 

exposure or cumulative exposure. The observed associations were not significantly affected by further 

adjustment for exposure to wood dust or organic solvents (Hildesheim et al. 2001).

In another study, investigators used data from five cancer registries in the United States to perform a 

multi-center population-based case-control study to examine the association between occupational 

exposures to formaldehyde and wood dust and nasopharyngeal cancer (Vaughan et al. 2000). Telephone 

interviews were conducted with 196 cases with epithelial nasopharyngeal cancers and 244 controls to 

collect demographic data and information on lifetime occupational history, history of chemical exposure, 

medical history, family history of cancer, and use of medication, alcohol, and tobacco. Exposures to 

formaldehyde and wood dust were estimated by industrial hygiene investigation and use of a job-exposure 
FORMALDEHYDE 57

matrix. The epithelial nasopharyngeal cancers were classified into one of three histological groups: 

epithelial, not otherwise specified (NOS) (n=24), undifferentiated or nonkeratinizing (n=54), or squamous 

cell (n=118). Potential exposure to formaldehyde was assessed in 40.3% of cases and 32.4% of controls. 

The adjusted OR for occupational exposure versus no exposure was 1.3 (95% CI 0.08–2.1) for all cancers. 

Trends were observed between increased nasopharyngeal cancer risk and increased duration of exposure 

and cumulative formaldehyde exposure. The OR associated with an exposure duration >18 years was 

2.7 (95% CI 1.0–4.5). The OR associated with cumulative exposure to >1.10 ppm-years compared to 

those considered unexposed was 3.0 (95% CI 1.3–6.6). There was no evidence of an association between 

formaldehyde exposure and the undifferentiated or nonkeratinizing histological subcategory. The ORs 

for formaldehyde were unaffected by the addition of wood dust to the logistic regression models

(Vaughan et al. 2000).

NTP (2005) noted that formaldehyde is reasonably anticipated to be a human carcinogen, and IARC 

(2006) indicated that the results of the study of former industrial workers from 10 U.S. formaldehyde 

related plants, supported by largely positive findings from other studies, provided sufficient 

epidemiological evidence that formaldehyde causes nasopharyngeal cancer in humans. More recently, 

IARC concluded that there is sufficient evidence in humans for a causal association of formaldehyde with 

leukemia (IARC 2009). IARC’s overall evaluation that formaldehyde is carcinogenic to humans 

(Group 1) was based on specific evaluations that there is sufficient evidence in both humans and 

experimental animals for the carcinogenicity of formaldehyde. Furthermore, EPA in 1991 and Integrated 

Risk Information System (IRIS) in 2010 classified formaldehyde as a Group B1–probable human 

carcinogen on the basis of limited evidence of carcinogenicity in humans and sufficient carcinogenicity 

evidence in laboratory animals. Duhayon et al. (2008) concluded that “human studies fail to raise a 

convincing conclusion concerning the carcinogenicity of formaldehyde and are not helpful to delineate a 

possible dose-response relationship.”
FORMALDEHYDE 58

Environment Canada/Health Canada (2001) and WHO (2002) have evaluated the mode of carcinogenic 

action for inhaled formaldehyde. The sustained increase in epithelial cell regenerative proliferation 

resulting from cytotoxicity is considered a requisite precursor in the mode of induction of nasal tumors in 

rats. Mutation, for which the formation of DNA-protein crosslinks serves as a marker of potential, may 

also contribute to the carcinogenicity of the compound in the nasal cavity of rats. The hypothesized mode 

of induction of formaldehyde-induced tumors was determined to satisfy several criteria for weight of 

evidence (i.e., consistency, concordance of exposure-response relationships across intermediate end

points, and biological plausibility and coherence of the database) and was considered likely relevant to 

humans, at least qualitatively. A biologically motivated case study was also provided that evaluated 

cancer risks by use of a two-stage clonal growth model. Estimates of carcinogenic risks using the human 

two-stage clonal growth model were developed for typical environmental exposures (i.e., continuous 

exposure throughout an 80-year lifetime to concentrations of formaldehyde ranging from 0.001 ppm to 

0.1 ppm [0.0012-0.12 mg/m3

]). The human clonal growth model predicted non-zero additional risks 

throughout the exposure ranges examined.

2.2.2 Oral Exposure 

Most of the available reports of controlled studies of health effects from oral exposure to formaldehyde 

have not provided information regarding how frequently dosing solutions were analyzed for 

formaldehyde content. Earlier, some studies reported how frequently formaldehyde solutions were 

prepared, but other study reports provided no information regarding solution-preparation frequency, 

conditions of storage, or analysis of test material for formaldehyde content (e.g., Soffritti et al. 2002;

Takahashi et al. 1986). Because of this reporting deficiency, and because formaldehyde solutions are 

very unstable (due to formaldehyde’s high reactivity and volatility), the reader should be aware that there 

is uncertainty associated with oral dose levels reported in this addendum. Another issue of uncertainty is

the impurity of commercially available aqueous solutions of formaldehyde (often called formalin), which 
FORMALDEHYDE 59

normally contain approximately 10–15% methanol to prevent polymerization. Attempts have been made, 

however, to note when formalin was the source of the ingested formaldehyde, so that the reader will be 

aware of possible confounding effects from methanol.

Case reports of human exposure are summarized in Table 2-3.

Table 2-3. Human Case Reports—Ingestion of Formalin

Reference Patient

Ingested dose

(mg/kg/day) Effects

Baccioglu and Kalpaklioglu 

2007

54-year-old 

male

233 Bronchospasm, respiratory crackles, 

bilateral lung infiltrates, fever, esophagitis,

gastritis

Yanagawa et al. 2007 28-year-old 

male

258 Acute respiratory distress, tachypnea and 

low blood pressure, esophageal erosion, 

gastric ulcers, gastric outlet obstruction, 

metabolic acidosis

2.2.2.2 Systemic Effects 

Respiratory Effects. Baccioglu and Kalpaklioglu (2007) described the case of a 54-year-old man who 

accidentally ingested 200 mL of a 10% solution of formaldehyde (233 mg/kg). Inhalation occurred while

the patient was vomiting and the patient developed cough, wheezing, dyspnea, and expectoration of blood 

2 days later. Bronchospasm and decreased FEV were observed, and bilateral infiltrates were seen on 

chest x-ray. Endoscopy showed low-grade esophagitis and gastritis. These pulmonary symptoms 

responded well to treatment with systemic corticosteroids and salbutamol. Two weeks after the accident, 

the patient experienced fever, increased white blood cells, massive expectoration of blood, bronchospasm, 

respiratory crackles, and new infiltrates on chest x-ray. The patient recovered following treatment with 
FORMALDEHYDE 60

antibiotics and steroids. Total and formaldehyde-specific IgE levels were normal, suggesting that 

observed pulmonary symptoms were not related to an allergic hypersensitivity response.

Yanagawa et al. (2007) described the case of a 28-year-old man who ingested 150 mL of a 40% solution 

of formalin (258 mg formaldehyde/kg) in an attempted suicide. He was alert when admitted to the 

hospital 2 hours following ingestion. Physical examination findings included erosions of the 

oropharyngeal mucosa, respiratory stridor, epigastric tenderness, and hypoactive bowel sounds. The 

patient was given sodium bicarbonate to treat metabolic acidosis and esophageal lesions. Acute 

respiratory distress developed, requiring mechanical ventilation, and bilateral pleural effusions noted on 

chest X-ray were drained by chest tubes. Tachycardia, low blood pressure, and oligouria developed and 

were treated with intravenous fluids and dobutamine. Mechanical ventilation ended on day 43, and the 

patient was discharged on day 73 following treatment for severe gastrointestinal effects.

Cardiovascular Effects. As previously discussed, Yanagawa et al. (2007) described the case of a 28-

year-old man who ingested 150 mL of a 40% solution of formalin (258 mg formaldehyde/kg) in an 

attempted suicide. The patient developed tachycardia, low blood pressure, and oligouria, which were 

treated with intravenous fluids and dobutamine. The patient eventually recovered and was released from 

the hospital following treatment for respiratory and gastrointestinal effects (see Respiratory Effects and 

Gastrointestinal Effects sections). 

Soffritti et al. (2002) did not observe treatment-related histopathological changes in the heart of male and 

female Sprague-Dawley rats given up to 188 mg/kg/day formaldehyde in drinking water for 104 weeks.

Gastrointestinal Effects. In the case described by Yanagawa et al. (2007) of a 28-year-old man who 

ingested 150 mL of a 40% solution of formalin (258 mg formaldehyde/kg) in an attempted suicide, the 

man was alert when admitted to the hospital 2 hours following ingestion. Physical examination findings 
FORMALDEHYDE 61

included erosions of the oropharyngeal mucosa, respiratory stridor, epigastric tenderness, and hypoactive 

bowel sounds. The patient was given sodium bicarbonate to treat metabolic acidosis and esophageal 

lesions. Acute respiratory distress developed, requiring mechanical ventilation, and bilateral pleural 

effusions noted on chest X-ray were drained by chest tubes. Tachycardia, low blood pressure, and 

oligouria developed and were treated with intravenous fluids and dobutamine. Mechanical ventilation 

ended on day 43 and the patient was discharged on day 73 following treatment for severe gastrointestinal 

effects.

Baccioglu and Kalpaklioglu (2007) described the case of a 54-year-old man who accidentally ingested 

200 mL of a 10% solution of formaldehyde (233 mg/kg). Endoscopy showed low-grade esophagitis and 

gastritis, which were treated with proton pump inhibitors and parenteral hydration. The patient recovered 

and was released from the hospital following treatment for respiratory effects related to formaldehyde 

aspiration during vomiting. Soffritti et al. (2002) did not observe non-neoplasic treatment-related lesions 

in the oral cavity, esophagus, stomach, or intestines of male and female Sprague-Dawley rats given up to 

188 mg/kg/day formaldehyde in drinking water for 104 weeks. Tumors of the stomach and small 

intestine were observed in this study. 

Hepatic Effects. Soffritti et al. (2002) did not observe treatment-related histopathological changes in 

the liver of male and female Sprague-Dawley rats given up to 188 mg/kg/day formaldehyde in drinking 

water for 104 weeks.

Renal Effects. Soffritti et al. (2002) did not observe treatment-related histopathological changes in the 

kidneys of male and female Sprague-Dawley rats given up to 188 mg/kg/day formaldehyde in drinking 

water for 104 weeks.
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Endocrine Effects. Soffritti et al. (2002) did not observe treatment-related histopathological changes 

in the adrenal, pituitary, thyroid, or pancreas of male and female Sprague-Dawley rats given up to 

188 mg/kg/day formaldehyde in drinking water for 104 weeks.

Dermal Effects. No adverse histopathology was noted in skin samples from male and female Wistar 

rats receiving ≤109 mg/kg/day formaldehyde in drinking water after 2 years of exposure (Til et al. 1989) 

or from male and female Sprague-Dawley rats receiving ≤188 mg/kg/day formaldehyde in drinking water 

after 2 years of exposure (Soffritti et al. 2002).

Ocular Effects. Soffritti et al. (2002) did not observe treatment-related histopathological changes in the 

Harderian gland of male and female Sprague-Dawley rats given up to 188 mg/kg/day formaldehyde in 

drinking water for 104 weeks.

Body Weight Effects. The daily food consumption and body weights of Sprague-Dawley rats 

(50/sex/group) administered formaldehyde for 104 weeks in the drinking water at concentrations of 10, 

50, 100, 500, 1,000, or 1,500 mg/L (1, 6, 13, 63, 125, or 188 mg/kg/day, respectively) were similar to

those of controls (100/sex/group) (Soffritti et al. 2002).

Metabolic Effects. Yanagawa et al. (2007) described the case of a 28-year-old man who ingested 

150 mL of a 40% solution of formalin (258 mg formaldehyde/kg) in an attempted suicide. The patient 

was given sodium bicarbonate to treat metabolic acidosis and eventually recovered following treatment 

for respiratory and gastrointestinal effects.
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2.2.2.3 Immunological and Lymphoreticular Effects 

Charpin et al. (2000) reported an allergic hypersensitivity reaction in an adult female following ingestion 

of formaldehyde in pharmaceutical preparations and toothpaste. A patch test was positive for 

formaldehyde, and oral challenge with a formaldehyde preparation resulted in recurrence of reported 

symptoms (headache, pharyngitis, dysphonia, and colitis), which lasted for approximately 24 hours.

Soffritti et al. (2002) did not observe treatment-related non-neoplastic lesions in the spleen, thymus, or 

subcutaneous, pancreatic, or mesenteric lymph nodes of male and female Sprague-Dawley rats given up 

to 188 mg/kg/day formaldehyde in drinking water for 104 weeks. An increase in the incidence of rats 

with hemolymphoreticular tumors was observed in this study (see Section 2.2.2.8).

2.2.2.4 Neurological Effects 

Soffritti et al. (2002) did not observe treatment-related histopathological changes in the brain or 

peripheral nervous system of male and female Sprague-Dawley rats given up to 188 mg/kg/day 

formaldehyde in drinking water for 104 weeks.

2.2.2.8 Cancer 

Soffritti et al. (2002) presented further analysis of the tumor data from rats treated with formaldehyde 

from 7 weeks of age, as described in the Soffritti et al. (1989) study. Statistical analysis of the tumor 

multiplicity data for malignancies (i.e., number of malignant tumors per 100 animals) indicated that a 

higher number of malignant tumors were found in males and females exposed to 1,000 or 1,500 ppm, in 

males exposed to 500 ppm, and in females exposed to 100 ppm compared to untreated controls. The 

incidence of animals with malignant tumors (i.e., number of tumor-bearing rats) was significantly 
FORMALDEHYDE 64

increased (p<0.05) only in males exposed to the highest formaldehyde concentration (1,500 ppm). An 

analysis of total hemolymphoreticular neoplasms was performed, and the analysis combined the incidence 

of leukemias and lymphomas and included the thymus, spleen, and subcutaneous, pancreatic, and 

mesenteric lymph nodes. The incidence of hemolymphoreticular neoplasms was significantly increased 

(p<0.05) in male rats exposed to 100, 500, 1,000, and 1,500 ppm and in female rats exposed to 1,000 and 

1,500 ppm. Additionally, Soffritti et al. (2002) suggested that formaldehyde ingestion increased the 

number of malignant mammary tumors in female rats and testicular interstitial cell adenomas in 

formaldehyde-exposed male rats (i.e., increased tumor multiplicity).

Environment Canada/Health Canada (2001) and WHO (2002) concluded that although there is no 

definitive evidence to indicate that formaldehyde is carcinogenic when administered orally to laboratory 

animals, the potential carcinogenic hazard associated with the ingestion of formaldehyde cannot be 

eliminated due to concerns about the known reactivity of this substance with biological macromolecules 

at the portal of entry and observations of histopathological and cytogenetic changes within the 

aerodigestive tract in rats administered formaldehyde orally. IARC (2006) summarized inconsistencies in 

the tumor findings across four drinking water studies in rats, but it did not provide an overall conclusion 

regarding the relevance of these data for assessing the potential for formaldehyde ingestion to induce 

cancer in humans. 

2.2.3 Dermal Exposure

Takahashi et al. (2007) conducted a prospective study of clinical symptoms and skin test reactions in 

143 medical students exposed to 2.4 ±0.49 ppm formaldehyde, 15 hours/week for 2 months. Skin 

irritation was reported in more than 25% of the students after repeated exposure to formaldehyde. 

Students with a history of atopic dermatitis (22 of 143 students) complained of skin irritation and redness 

more often than students without a history of atopic dermatitis. Positive patch testing was reported for 

only 2 of 60 students (3.3%) (one male with allergic hand dermatitis due to direct contact with a cadaver 
FORMALDEHYDE 65

and one female with an atopic background and symptoms). Negative patch test findings were also 

reported for 58 students similarly exposed to formaldehyde 2–4 years previously.

2.2.3.3 Immunological and Lymphoreticular Effects 

Xu et al. (2002) further evaluated contact hypersensitivity to formaldehyde and the cytokine response in 

mouse skin, spleen, and lymph nodes. Mice received three topical applications (1/day) of 100 μL of 

17.5% formaldehyde to the shaved abdominal skin. To induce contact hypersensitivity to formaldehyde, 

both ears were painted with 2% formaldehyde on day 3 following the last abdominal application. Mouse 

ear thickness was measured immediately before ear challenge and 24 hours later. Mice were sacrificed 3, 

5, 7, 9, and 12 days after the last abdominal application, and ear skin, spleen, and draining lymph nodes 

were removed for evaluation of cytokine expression. Formaldehyde challenge induced a weak contact 

hypersensitivity response (i.e., ear swelling) and increased expression of IL-4 and IFN-γ in mouse ear 

skin. Abdominal application of formaldehyde produced a lasting expression of IL-4 and IFN-γ and a 

transient increase in IL-13 in spleen and draining lymph nodes. Additional cytokines (IL-2, IL-15, 

IL-12p40) were expressed only in the spleen following dermal exposure to formaldehyde.
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2.3 TOXICOKINETICS 

2.3.3 Metabolism

2.3.3.1 Inhalation Exposure

The ability of respiratory and olfactory tissues to oxidize formaldehyde was examined in male F-344 rats. 

To determine the effects of repeated formaldehyde exposure on enzyme activities, rats were exposed to 

15 ppm formaldehyde 6 hours/day for 10 days. At the completion of formaldehyde exposure, rats were 

sacrificed, and respiratory and olfactory mucosal tissues were harvested. The enzymatic capacity of the 

tissues was determined in the presence and absence of glutathione. Tissue homogenates from both the 

respiratory and olfactory mucosa demonstrated the ability to oxidize formaldehyde. The oxidation of 

formaldehyde occurred at similar rates in the respiratory and olfactory mucosal homogenates. Human 

bronchial epithelial cells were shown to bio-transform formaldehyde to formic acid at a relatively fast rate 

(i.e., similar to rat hepatocytes) for concentrations up to 3 mM (Ovrebo et al. 2002).

2.3.5 Physiologically Based Pharmacokinetic (PBPK)/Pharmacodynamic (PD) Models

Computational Fluid Dynamics (CFD) models of airflow in the nasal passages of rats, monkeys, and 

humans have been developed to determine the degree to which interspecies and interregional differences 

in uptake patterns along airway passages may account for differing distributions of formaldehyde-induced 

upper respiratory tract lesions in rats and primates. These models enable extrapolation of exposures 

associated with upper respiratory tract tissue damage in rats or monkeys to human exposures (Cohen 

Hubal et al. 1997; Kepler et al. 1998; Kimbell and Subramaniam 2001; Kimbell et al. 1997a, 1997b, 

2001a, 2001b; Morgan 1997; Subramaniam et al. 1998). Airflow pattern is expected to be one of three 

important determinants of upper respiratory tract tissue uptake, along with interactions at the airway/
FORMALDEHYDE 67

tissue interface, such as off-gassing and tissue properties influencing absorption rates (e.g., mucociliary 

clearance or rate of biotransformation).

Kimbell et al. (2001b) described a flux binning approach where the nasal surface of the rat, monkey, and 

human were partitioned by flux into smaller regions characterized by surface area and average flux rate. 

There was a decreasing gradient of flux observed from proximal to distal nasal sites in all three species; 

however, the gradient was predicted to be less steep in humans than for rats or monkeys. Human nasal 

flux patterns shifted distally, and uptake percentage decreased as the inspiratory flow rate increased.

Overton et al. (2001) described an anatomical model of formaldehyde dosimetry for the entire respiratory 

tract that applied one-dimensional mass transport equation. This model was made consistent with CFD 

nasal models by using similar values for air flow rate and uptake during inspiration in the nasal passages. 

Tracheo-bronchial flux was predicted to be larger than flux in the first pulmonary region, and there was 

essentially no predicted flux in the alveolar sacs. This model also suggested that >95% of inhaled 

formaldehyde is predicted to be retained in the respiratory tract. Franks (2005) also provided a 

mathematical model demonstrating that insignificant amounts of formaldehyde enter the systemic 

circulation following absorption and metabolism in nasal tissues. Schlosser (1999) suggested that as 

much as 2% to 22 of inhaled formaldehyde may be removed by nasal mucus flow (Overton et al. 2001).

Conolly et al. (2000) extended the rat model developed by Hubal et al. (1997) to the Rhesus monkey and 

humans. Essential inputs to the tissue model were site-specific flux predictions provided by anatomically 

realistic CFD models for the nasal airways and site-specific mucosal epithelial thickness estimates 

measured in rats and Rhesus monkeys. Regional DNA-protein cross link data were obtained for the rat 

(Casanova et al. 1991) and Rhesus monkey (Casanova et al. 1994). The thickness of the nasal mucosa 

was measured at high and low tumor sites in the rat nose and at several locations in the nasal cavity of the 

Rhesus monkey (anterior lateral walls and septum, the nasopharynx, and the middle turbinates). The 
FORMALDEHYDE 68

human model was developed on the basis of allometric scaling from the rat and monkey data. The 

empirical strength of an allometric relationship derived from regressing two data points (rat and monkey) 

has, however, been characterized as extremely weak by Subramaniam et al. (2008). As described for 

Hubal et al. (1997), each model describes three disposition processes for formaldehyde: a saturable 

pathway representing enzymatic bio-transformation of formaldehyde, a separate first-order pathway 

representing the intrinsic reactivity of formaldehyde with tissue constituents, and pseudo first-order 

binding to DNA. The rat model accurately predicted the concentration of DNA-protein cross links in the 

high and low tumor regions of the rat nasal cavity. The Rhesus monkey model also provided good fit to 

the data for DNA-protein cross links in different regions of the nose. In the human model, differences in 

the predictions of DNA-protein cross links between regions are accounted for by site-specific tissue 

thickness and flux estimates. Georgieva et al. (2003) further refined the rat model described by Conolly 

et al. (2000) by including measurements of nasal tissue thickness and DNA distribution maps for 

respiratory and transitional nasal epithelium. Sensitivity analysis of this model indicated that model fit 

was sensitive to Vmax and predictions were sensitive to changes in tissue thickness.

Two approaches have been proposed for using the CFD and pharmacokinetic models to extrapolate doseresponse relationships for formaldehyde-induced rat nasal tumors and related end points, such as rates of 

cellular proliferation in specific regions of the nasal epithelium to derive estimates of cancer risks in 

humans. One approach makes predictions for respiratory tract cancer risks in humans by using an 

approximation to a two-stage clonal growth cancer model incorporating data on cell division rates, 

number of cells at risk, tumor incidence, DNA-protein cross link measurements, and site-specific flux of 

formaldehyde (see also CIIT 1999; Conolly et al. 2000, 2003, 2004; Kimbell et al. 2001a; Overton et al 

2001). Conolly et al. (2002) and Gaylor et al. (2004) described the analysis of dose-response data for 

nasal regenerative cell proliferation, which is characterized by a non-monotonic or J-shaped doseresponse curve. However, Subramaniam et al. (2008) analyzed the large uncertainty and variability in the 

labeling index data (from which cell replication rates were derived) and concluded that, given these 
FORMALDEHYDE 69

qualitative and quantitative uncertainties and in their interpretation, a variety of cell replication doseresponse models that included both non-monotonic and monotonically-increasing shapes are plausible as 

reasonable characterization of the data. Conolly et al. (2002) and Gaylor et al. (2004) described the

analysis of dose-response data for nasal regenerative cell proliferation, which is characterized by a nonmonotonic or J-shaped dose-response curve. 

The two-stage clonal expansion model was developed to link DNA-protein cross links and regenerative 

cell proliferation. A novel contribution of the CIIT model is that cell replication rates and DNA-protein 

cross links concentrations are driven by local formaldehyde dose, a feature that is important in the case of 

a highly reactive gas like formaldehyde for which uptake patterns are spatially localized and significantly 

different across species (Kimbell et al. 2001). DNA-protein cross links concentration levels were 

incorporated into the two-stage clonal expansion model as a dose surrogate for the putative directly 

mutagenic action of formaldehyde. The modeling in Conolly et al. (2003, 2004) concluded that cancer 

risks at environmental exposures were negligible and that the directly mutagenic action of formaldehyde 

does not play a significant role in tumor formation by the use of nasal dosimetry predicted by using CFD 

models (Conolly et al. 2003, 2004). 

The CIIT modeling and available data have been evaluated in a series of peer-reviewed papers (Crump et 

al. 2008; Subramaniam et al. 2007, 2008) and debated further in the literature (Conolly et al. 2009; Crump 

et al. 2009). Subramaniam et al. (2007) and Crump et al. (2008) considered several alternative 

formulations of the modeling in Conolly et al. (2000, 2003, 2004). These authors claimed that their 

alternate implementations were consistent with the available mechanistic and nasal tumor incidence data, 

yet yielded estimates of low-dose risk that varied by many orders of magnitude, even when only 

maximum likelihood estimates of risk were considered. Modeling results were extremely sensitive to 

assumptions on the kinetics of initiated cells for which there were no data and to the use of data from 

historical control animals (Crump et al. 2008, 2009; Subramaniam et al. 2008). Furthermore, 
FORMALDEHYDE 70

Subramaniam et al. (2007) concluded that a substantial contribution from formaldehyde’s mutagenic 

potential could be needed in the model to explain formaldehyde tumorigenicity. 

A second approach (a benchmark dose approach) makes predictions of nasal cancer risk in humans by 

using curve fitting of relevant rat exposure-response data (e.g., nasal tumors or precursor lesions such as 

pre-neoplastic foci or squamous papillomas, rates of cellular proliferation, or rates of DNA-protein cross 

link formation) and CFD modeling and/or pharmacokinetic modeling for extrapolation purposes (CIIT 

1998; Schlosser et al. 2003). Benchmark concentrations were lower for cell proliferation than for tumors. 

Two extrapolation methods were employed, including a CFD model used to determine the rate of delivery 

of formaldehyde to the nasal lining and a CFD method combined with a pharmacokinetic model to predict 

formaldehyde dose by using DNA-protein cross links as a dose metric. Both extrapolation methods gave 

similar results (Schlosser et al. 2003).

2.4 MECHANISMS OF ACTION 

2.4.1 Pharmacokinetic Mechanisms 

Several studies have suggested that distant site effects of formaldehyde are associated with the production 

of reactive oxygen species in blood, liver, kidneys, and testes (Kum et al. 2007; Petushok 2000; Sogut et 

al. 2004; Zararsiz et al. 2006; Zhou et al. 2006). Studies in isolated cell systems suggest that oxidative 

stress may play a role in formaldehyde-induced cytoxicity (Ayaki et al. 2005; Saito et al. 2005; Teng et al. 

2001). Administration of Vitamin E was shown to protect against oxidative damage by formaldehyde in 

the plasma, liver, and brain of rats. Formaldehyde was administered by intraperitoneal injection in these 

studies, so that the significance of these findings is unclear (Gulec et al. 2006a; Gurel et al. 2005). Zhou 

et al. (2006) showed that pretreatment of rats with Vitamin E prevented the testicular toxicity observed 

after inhalation of 8 ppm formaldehyde 12 hours/day for 2 weeks.
FORMALDEHYDE 71

An example of a local effect of formaldehyde vapor was demonstrated in the rat nasal epithelium. The 

mechanisms responsible for formaldehyde deposition in the nasal cavity are well understood. The 

patterns of air flow are related to the anatomical structure of the nasal passages (Kimbell 2006). 

Formaldehyde dissolves in the nasal mucosal tissue upon contact due to its high water solubility. The 

reactivity of formaldehyde leads to interaction with proteins and other macromolecules at the site of 

contact in the nose (Medinsky and Bond 2001). In rat studies where cell turnover was measured (a 

measure of formaldehyde cytotoxicity), the no-effect level is approximately 2 ppm (Monticello et al. 

1991) for 6 hours/day exposures for ≤9 days. At higher concentrations (6, 10, or 15 ppm), higher rates of 

cell turnover were seen (Monticello et al. 1991) and a dose-response was observed. The increase in cell 

proliferation (as measured by thymidine incorporation) was more sensitive to formaldehyde exposure than 

histopathological changes. Similar results were seen in a 6-week experiment at these same doses in 

which the rats were exposed 5 days/week. Monticello et al. (1996) also determined that the nasal cell 

target population size, increased cell proliferation of specific target cells (due to differences in regional 

airflow with the rat nasal cavity), and the nonlinear kinetics of formaldehyde binding to DNA explain 

why specific regions of the rat nose are more prone to develop formaldehyde-induced nasal squamous cell 

carcinomas than other sites in the nasal cavity. 

McGregor et al. (2006) proposed a cancer mode of action for formaldehyde based on the induction of 

sustained cytotoxicity and regenerative cell proliferation. Dose-response and temporal relationships were 

consistent with key events for this mode of action, although genotoxicity could not be conclusively ruled 

out as possibly contributing to carcinogenicity. The proposed mode of action was considered to be 

potentially relevant to humans, although human data for key events are limited. Environment 

Canada/Health Canada (2001) and WHO (2002) have evaluated the mode of carcinogenic action for 

inhaled formaldehyde. The sustained increase in epithelial cell regenerative proliferation resulting from 

cytotoxicity is considered a requisite precursor in the mode of induction of nasal tumors in rats. 
FORMALDEHYDE 72

Mutation, for which the formation of DNA-protein crosslinks serves as a marker of potential, may also 

contribute to the carcinogenicity of the compound in the nasal cavity of rats. The hypothesized mode of 

induction of formaldehyde-induced tumors was determined to satisfy several criteria for weight of 

evidence (i.e., consistency, concordance of exposure-response relationships across intermediate 

endpoints, and biological plausibility and coherence of the database) and was considered likely relevant to 

humans, at least qualitatively.

 

Several recent studies have described changes in gene expression that are associated with formaldehydeinduced toxicity in the respiratory tract (Feick et al. 2006; Hester et al. 2003, 2005; Lee et al. 2008; 

Thomas et al. 2007; Yang et al. 2005). Formaldehyde exposure produced changes in the expression of 

genes related to cell proliferation and differentiation, immunity and inflammation, xenobiotic metabolism, 

cytoskeletal integrity, cell cycle, apoptosis, and DNA repair.

It has been suggested that formaldehyde inhalation may produce or exacerbate allergic effects or asthma 

in children or adults (Mendell 2007; Sakamoto et al. 1999). Individuals with allergic conditions or 

respiratory disease may be more sensitive to the effects of irritants (Mendell 2007; Sakamoto et al. 1999). 

The possible mechanisms for these effects have not been fully determined; however, it has been suggested 

that formaldehyde may facilitate an IgE sensitization to other antigens or may produce an IgE-mediated 

response to itself (Sakamoto et al. 1999). There are only a few available case reports of bronchial asthma 

suggestive of respiratory tract sensitization to formaldehyde gas (Kim et al. 2001; Lemiere et al. 1995),

and the mechanism of sensitization in these subjects is uncertain. Several studies have examined serum 

for formaldehyde-specific IgE antibodies in groups of formaldehyde-exposed humans (Doi et al. 2003; 

Dykewicz et al. 1991; Grammer et al. 1990; Kim et al. 1999; Wantke et al. 1996a, 1996b). In general, the 

studies do not provide consistent evidence for a formaldehyde-induced allergic respiratory syndrome, but

they provide suggestive evidence that children may have an increased tendency to develop specific 

antibodies after exposure to low levels of formaldehyde in indoor air (Wantke et al. 1996a). Some animal 
FORMALDEHYDE 73

experiments suggest that exposure to formaldehyde may enhance allergic responses of the respiratory 

tract to other respiratory allergens (Riedel et al. 1996; Tarkowski and Gorski 1995). Casset et al. (2006) 

indicated that acute formaldehyde exposure (by mouth-breathing only) could affect the bronchial response 

to mite allergen in human subjects with mild asthma and allergic sensitization to house dust mites. 

However, a similar study did not demonstrate an effect of formaldehyde exposure on allergenic responses 

in human subjects with intermittent asthma and allergy to grass pollen (Ezratty et al. 2007). These 

investigators suggested that further research is necessary to confirm the hypothesis of formaldehyde 

facilitation of other respiratory allergens and to determine if this is relevant to humans exposed to 

formaldehyde (Ezratty et al. 2007). The dermal sensitization response in experimental animals involves 

an increase in the production of proinflammatory cytokines (Dearman et al. 1999; Hilton et al. 1996; 

Ushio et al. 1999; Xu et al. 2002); however, this mechanism has not been clearly demonstrated in the 

respiratory tract (Fujimaki et al. 2004, 2005; Jung et al. 2007).

2.4.3 Animal-to-Human Extrapolations 

As described in a draft document by EPA (1991), the formaldehyde rat study by Kerns et al. (1983) was 

the best animal study for cancer risk extrapolation for human cancer risks at low exposure concentrations; 

it used rates of DNA-protein cross links in target tissue as a measure of delivered dose (Hernandez et al. 

1994). Adjustments to continuous exposure were used to calculate lifetime human cancer unit risk 

estimates of 3.3x10-4 ppm formaldehyde based on monkey data and of 2.8x10-3 ppm formaldehyde based

on rat data (Hernandez 1994). 

As discussed in Section 2.3.5, two approaches have been proposed for using the CFD and 

pharmacokinetic models to extrapolate exposure-response relationships for formaldehyde-induced rat 

nasal tumors and related end points, such as rates of cellular proliferation in specific regions of the nasal 

epithelium, to derive estimates of cancer risk in humans exposed to inhaled formaldehyde. One approach 
FORMALDEHYDE 74

makes predictions for respiratory tract cancer risk in humans exposed to inhaled formaldehyde by using 

two-stage clonal-growth cancer models incorporating data on cell division rates, numbers of cell at risk, 

tumor incidence, and site-specific flux of formaldehyde (see also CIIT 1998; Conolly and Andersen 1993; 

Conolly et al. 1992, 2003, 2004; Morgan 1997). A second approach (a benchmark dose approach) makes 

predictions of nasal cancer risk in humans by using curve fitting of relevant rat exposure-response data 

(e.g., nasal tumors or precursor lesions such as preneoplastic foci or squamous papillomas, rates of 

cellular proliferation, or rates of DNA-protein cross link formation) and CFD modeling and/or 

pharmacokinetic modeling for extrapolation purposes (CIIT 1998; Schlosser et al. 2003).

2.5 Relevance to Public Health

As presented in the 1999 Toxicological Profile for Formaldehyde, the following MRLs were derived for 

formaldehyde:

Inhalation MRLs

• An MRL of 0.04 ppm has been derived for acute-duration exposure.

• An MRL of 0.03 ppm has been derived for intermediate-duration exposure.

• An MRL of 0.008 ppm has been derived for chronic-duration exposure.

Oral MRLs

• An MRL of 0.3 mg/kg/day has been derived for intermediate-duration exposure.

• An MRL of 0.2 mg/kg/day has been derived for chronic-duration exposure.

For details on these MRLs, refer to the 1999 formaldehyde profile available at: 

http://www.atsdr.cdc.gov/ToxProfiles/tp.asp?id=220&tid=39.
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ATSDR is currently in the process of re-evaluating the MRLs for formaldehyde. The evaluation is 

pending review of US EPA toxicological review of formaldehyde by a committee of the National 

Research Council (NRC) (IRIS 2010).

2.6 CHILDREN’S SUSCEPTIBILITY 

A recent review by Mendell (2007) suggested that indoor residential exposure to formaldehyde may be 

associated with risk of asthma, allergies, and pulmonary infections in children. Several epidemiology 

studies have examined the relationship between residential formaldehyde exposure and asthma and/or 

allergies. However, inconsistent findings were reported. Krzyzanowski et al. (1990) reported that 

children who lived in households with formaldehyde air concentrations >0.06 ppm had greater prevalence 

rates of physician-diagnosed bronchitis or asthma than children who lived in households with 

concentrations <0.06 ppm. Franklin et al. (2000) reported that residential formaldehyde concentrations of 

>0.05 ppm did not affect pulmonary function variables (FVC or FEV1) in 224 healthy children (6 to 

13 years old). This study did not provide a concentration range for the children exposed to >0.05 ppm. 

Rumchev et al. (2002) suggested that young children 6 months to 3 years old with exposure to 

formaldehyde concentrations >0.06 mg/m3 (0.049 ppm) are at a 39% increased risk of asthma than

children not exposed to such levels. Venn et al. (2003) performed a case-control study of 193 children (9

to 11 years old) with persistent wheezing and 223 healthy controls. There were no significant differences

in formaldehyde concentrations in the homes between the cases and controls. However, there was an 

association between increased frequency of symptoms (i.e.,wheezing) and formaldehyde in the homes of 

the cases. The adjusted OR for increased symptoms was 1.4 (95% CI 1.0–1.9). Smedje et al. (1997) 

reported an association between formaldehyde concentration in the classroom and the prevalence of 

current asthma (OR 1.1, 95% CI 1.01–1.2) in Swedish school children. Current asthma was defined as 

physician-diagnosed asthma with current symptoms and/or current asthma treatment. Delfino et al. 

(2003) reported an association between ambient formaldehyde concentration and the severity of 
FORMALDEHYDE 76

symptoms reported by 22 asthmatic children (10–16 years old) living in a Los Angeles community with 

high traffic density. The adjusted OR for bothersome or more severe asthma with an IQR increase (0.003 

ppm) in formaldehyde was 1.37 (95% CI 1.04–1.8) with a 1-day lag. There was no relationship between 

formaldehyde concentration and PEFR. Garrett et al. (1999) observed a trend between the residential 

formaldehyde concentration and the proportion of atopic children, using a cross-sectional survey of 80 

homes in Australia (148 children, 53 of whom were asthmatic). The number of positive skin prick tests 

and the average size of the allergen wheal were increased in the highest formaldehyde exposure category 

(>0.05 mg/m3

, >0.04 ppm) compared to the lowest formaldehyde exposure group (<0.02 mg/m3 or <0.02 

ppm). No relationship between formaldehyde exposure and asthma was observed in this study. In a 

cross-sectional, case-control study, Tavernier et al. (2006) investigated the home environment of 105 

asthmatic children (4–17 years old) and 95 healthy controls. There were no differences in indoor air 

concentrations of formaldehyde in the homes of the cases and controls. The results of these studies 

indicated that low residential indoor air levels of formaldehyde may predispose young children to asthma 

or allergies. However, the dose-response relationship has not been clearly established and further 

research is necessary. 

2.7 BIOMARKERS OF EXPOSURE AND EFFECT 

2.7.1 Biomarkers Used to Identify or Quantify Exposures to Formaldehyde 

Formaldehyde that is not rapidly metabolized to formate can react with a variety of cellular components,

including nucleotides, proteins, and glutathione, to form adducts, such as N6-hydroxymethyldeoxyadenosine and N2-hydroxymethyldeoxyguanosine, and DNA-protein cross links. Several of these 

formaldehyde-induced products have been examined as potential biomarkers of exposure for repeated 

exposure to formaldehyde. A method for detecting biomarkers such as N6

-hydroxymethyldeoxyadenosine and N2

-hydroxymethyldeoxyguanosine (the major adducts formed by formaldehyde in vitro) 
FORMALDEHYDE 77

had experimental complications and does not appear to provide useful biomarkers of formaldehyde 

exposures (Fennell 1994). Zhong and Que Hee (2004) described a high performance liquid 

chromatography (HPLC) method to identify and quantify formaldehyde DNA adducts isolated from 

human nasal epithelial cells. Analysis of formaldehyde-modified deoxynucleosides may serve as a useful 

biomarker for samples obtained from nasal lavage or biopsy. N-Methylvaline is a molecular adduct that 

is formed by the reaction of formaldehyde with hemoglobin. Bono et al. (2006) demonstrated an 

association between formaldehyde exposure in plywood and laminate factory workers (n=21) and the 

occurrence of N-methylvaline in blood. However, this assay could not distinguish between subjects 

exposed to formaldehyde through tobacco smoke, on the one hand, and nonsmokers, on the other.

Many studies conducted earlier (e.g., Casanova and Heck 1987; Casanova et al. 1989a, 1989b, 1991, 

1994; Casanova-Schmitz et al. 1984a) used radiolabeled compounds tagged with 14C and/or 3

H to 

facilitate detection of DNA-protein cross links. However, this approach would not work to detect past 

exposures in humans. The formation of DNA-protein cross links in isolated rat nasal epithelial cells 

(respiratory and olfactory epithelial cells) incubated with formaldehyde has also been reported 

(Kuykendall et al. 1995). Using a sensitive technique to detect total DNA-protein cross links, Shaham et 

al. (1996, 2003) reported that cultured human white blood cells showed increasing quantities of DNAprotein cross links when cultured in media with increasing formaldehyde concentrations and that a small 

group of formaldehyde-exposed persons had a significantly greater mean amount of DNA-protein cross 

links in their white blood cells than did a group of non-exposed persons. Although DNA-protein cross 

links are known to be formed by other agents such as ionizing radiation and alkylating agents, Shaham et 

al. (1996, 2003) concluded that their results suggested that levels of DNA-protein cross links in white 

blood cells may provide an indicator of formaldehyde-induced tissue damage and a biomarker of 

occupational exposure to formaldehyde.
FORMALDEHYDE 78

2.7.2 Biomarkers Used to Characterize Effects Caused by Formaldehyde 

Increased eosinophil concentration and increased levels of albumin and total protein have been found in 

nasal lavage fluid taken from subjects exposed to 0.4 ppm formaldehyde for 2 hours (Krakowiak et al. 

1998). Although these variables are not expected to be influenced only by formaldehyde exposure, they 

appear to be promising biomarkers of acute respiratory irritation from airborne formaldehyde.

Franklin et al. (2000) reported that exhaled nitric oxide levels were elevated in children living in homes 

with formaldehyde concentrations of >0.05 ppm compared to children living in homes with formaldehyde 

concentrations of <0.05 ppm. This was considered to represent a subclinical inflammatory response in 

the airways of healthy children, because there was no effect on pulmonary function in children in this 

study. Although exhaled nitric oxide is a potential marker of eosinophilic airway inflammation in atopic 

airways, it has limited use as a biomarker because it is not specific to formaldehyde and may be affected 

by a number of factors, including allergic disease, atopic sensitization, age, and gender.

Iarmarcovai et al. (2007) suggested that evaluation of the number of centromeric signals in a 

micronucleus assay can provide information about the mechanism of genotoxicity and can serve as a

biomarker of genotoxic effects. Peripheral blood lymphocytes obtained from pathologists and anatomists 

exposed to formaldehyde (n=18) showed an increase in centromere-positive micronuclei with a single 

centromere. These data suggest that impaired chromosome migration may contribute to aneuploidy 

following prolonged exposure to formaldehyde (Iarmarcovai et al. 2007).

Several studies have evaluated gene expression profiling following formaldehyde exposure and have 

suggested that genes and/or proteins that are up- or- down-regulated may eventually be used as 

biomarkers for the effects of formaldehyde (Im et al. 2006; Lee et al. 2008; Li et al. 2007; Sul et al. 2007).
FORMALDEHYDE 79

2.8 INTERACTIONS WITH OTHER CHEMICALS 

Mautz (2003) examined the potential interaction between ozone and formaldehyde on respiratory tract 

toxicity in exercising animal models. Rats were exposed to 10 ppm formaldehyde and 0.6 ppm ozone, 

alone or in combination, at rest and during exercise. Combined exposure to ozone and formaldehyde 

resulted in greater nasal epithelial injury than formaldehyde exposure alone. The injury to lung 

parenchyma produced by ozone was not enhanced by formaldehyde, suggesting that formaldehyde does 

not effectively penetrate to the distal portions of the respiratory tract, even during exercise. The 

respiratory toxicity of formaldehyde and ozone, alone or in combination, was increased by exposure,

compared to resting exposure conditions.

Kum et al. (2007) evaluated the effects of xylene and formaldehyde inhalation on hepatic oxidative stress 

in the adult and developing rat. Rats were exposed to technical xylene (300 ppm), formaldehyde (6 ppm),

or both 8 hours/day for 6 weeks. No effects were seen in the livers of adult rats. However, biomarkers of 

oxidative stress (i.e., catalase and superoxide dismutase activity, glutathione content) were altered in the 

developing rat liver after exposure to formaldehyde and xylene. The effects of combined exposure did 

not differ from the effects seen following exposure to the individual chemicals.

2.10 METHODS FOR REDUCING TOXIC EFFECTS 

The following texts provide specific information about treatment following exposures to formaldehyde: 

Caraccio TR, McGuigan MA. 2004. Formaldehyde and glutaraldehyde. In: Dart RC, ed. Medical 

toxicology. Philadelphia, PA: Lippincott Williams & Wilkins, 1246–1250.

Goldfrank LR, Flomenbaum NE, Lewin NA, et al., eds. 2002. Formaldehyde. In: Goldfrank's 

toxicologic emergencies. New York, NY: McGraw-Hill, 1284.
FORMALDEHYDE 80

Leikin JB, Paloucek JB. 2002. Formaldehyde. In: Leikin and Paloucek's poisoning and toxicology 

handbook. Hudson, OH: Lexi-Comp, Inc., 600–602.

Viccellio P, Bania T, Brent J, et al., eds. 1998. Formaldehyde. In: Emergency toxicology. Philadelphia, 

PA: Lippincott-Raven Publishers, 519–522.

The primary concern after oral intoxication with formaldehyde is correcting the severe acidosis and 

decreased blood pressure that this chemical induces. Treatment should be aimed at increasing the blood 

pressure to a somewhat normal state (sympathomimetic drugs may be used) as well as treating the 

acidosis with bicarbonate (Caraccio and McGuigan 2004; Goldfrank et al. 2002; Leikin and Paloucek 

2002; Viccellio et al. 1998). Dialysis may also be used to remove excess formate (as formic acid) in the 

blood in order to correct the acidosis (Caraccio and McGuigan 2004; Goldfrank et al. 2002; Leikin and 

Paloucek 2002).

2.10.1 Reducing Peak Absorption Following Exposure 

Human exposure to formaldehyde may occur by inhalation, ingestion, or dermal contact. There are no 

known antidotes to formaldehyde poisoning in humans, particularly after oral exposure. General 

recommendations for reducing absorption of formaldehyde include removing the exposed individual from 

the contaminated area and removing contaminated clothing, if applicable. If the eyes and skin were 

exposed, they should be flushed with copious amounts of water. Since formaldehyde is highly corrosive, 

vomiting after oral ingestion should not be induced. The stomach contents can be diluted with milk or 

water by mouth if the patient is alert and responsive; otherwise, gastric lavage may be indicated. A bolus 

of charcoal and isotonic saline cathartic may also be useful (Goldfrank et al. 2002; Leikin and Paloucek 

2002).
FORMALDEHYDE 81

2.10.2 Reducing Body Burden 

Despite a relatively fast clearance of formaldehyde from the body, toxic effects may develop in exposed 

individuals, particularly in cases of acute oral poisonings that quickly overwhelm the body’s natural 

mechanisms to metabolize formaldehyde (particularly via formaldehyde dehydrogenase). With the 

exception of sodium bicarbonate administration and hemodialysis to remove excess formate from the 

blood, there is no standard method or practice to enhance the elimination of the absorbed dose of 

formaldehyde (Caraccio and McGuigan 2004; Goldfrank et al. 2002; Leikin and Paloucek 2002).

2.11 ADEQUACY OF THE DATABASE 

2.11.2 Identification of Data Needs 

Acute-Duration Exposure. Results from human and animal studies indicate that portal-of-entry 

tissues are the critical targets of acute-duration exposures to formaldehyde: the nose and eyes with 

inhalation exposure; the gastrointestinal tract with oral exposure; and the skin with dermal exposure.

Studies of humans under controlled conditions clearly indicate that acute exposures to air concentrations

of formaldehyde gas range from 0.4 to 3 ppm (Bender et al. 1983;Day et al. 1984; Gorski et al. 1992; 

Krwakowiak et al. 1998; Kulle 1993; and Lang et al. 2008).

Intermediate-Duration Exposure. Intermediate-duration exposure to formaldehyde is expected to 

affect the same critical targets as acute exposure: the upper respiratory tract with inhalation exposure; the 

gastrointestinal tract with oral exposure; and the skin with dermal exposure. 
FORMALDEHYDE 82

Although there are numerous human studies of acute inhalation toxicity from formaldehyde (controlledexposure and occupational exposure studies) and numerous investigations of toxic effects from chronic 

occupational exposures, only a few studies of humans exposed for intermediate durations were located. 

Eye, nose, and throat irritation were observed in medical students exposed to formaldehyde for 2–

3 months during gross anatomy class (Kim et al. 1999; Kriebel et al. 2001; Takahashi et al. 2007; 

Takigawa et al. 2005; Wei et al. 2007). Formaldehyde exposure concentrations were highly variable 

during the exposure period (0.1–10 ppm formaldehyde), and symptom reporting by study participants was 

used as the primary effect measure. Objective measures of formaldehyde irritation (i.e., clinical 

examination, nasal lavage, nasal biopsy) were not examined in these studies. 

Children’s Susceptibility. 

There is some evidence to suggest that formaldehyde may contribute to or worsen the symptoms of 

asthma in children (Delfino et al. 2003; Rumchev et al. 2002; Smedje et al. 1997; Venn et al. 2003); 

however, inconsistent findings have been reported (Franklin et al. 2000; Garrett et al. 1999; Tavernier et 

al. 2006). Studies that evaluate the effect of early life exposure (<2 years) to formaldehyde on the 

subsequent development of respiratory disease are needed.

There is a need to further study the effects of formaldehyde-bound particles from acute, intermediate, and 

chronic exposures. There is also a need to study the effects of formaldehyde in the presence of other 

chemicals and the potential for resulting interactive effects. 

2.11.3 Ongoing Studies 

Barbara A. Sorg of the Washington State University is researching an animal model for chemical 

intolerance, sponsored by the National Institute for Environmental Health Sciences (NIEHS) (CRISP 

2008).
FORMALDEHYDE 83

3. CHEMICAL AND PHYSICAL INFORMATION

No updated information.

4. PRODUCTION, IMPORT/EXPORT, USE, AND DISPOSAL

4.1 PRODUCTION

Production volume of formaldehyde (37% by weight basis) in the United States in 1990, 1995, and 2000 

were reported to be 7.5, 8.7, and 10.3 billion pounds, respectively (IARC 2006). From 1995 to 2000, 

formaldehyde production averaged an annual growth rate of 1.8% per year and was predicted to grow at a 

rate of 1.0% per year through 2004 (CMR 2001). The estimated total annual formaldehyde capacities in 

1998 and 2001 were 11.3 and 12.5 billion pounds, respectively (C&EN 1998; CMR 2001). The annual 

growth rate of formaldehyde production from 2001 to 2006 was 0.9% per year, and was predicted to grow 

at a rate of 1.0% per year through 2010 (CMR 2007). The total annual capacity of formaldehyde

production (37% solution basis) in the United States in 2007 was 11.9 billion pounds (SRI 2007). 

Table 4-1 shows capacity and production volumes for selected years between 1960 and 2007.

As of 2007, three manufacturers of formaldehyde were responsible for over 50% of the annual capacity 

for the United States: Georgia-Pacific Chemicals LLC. (Albany, Oregon; Columbus, Ohio; Conway, 

North Carolina; Crossett, Arkansas; Grayling, Michigan; Louisville, Mississippi; Lufkin, Texas; 

Russellville, South Carolina; Taylorsville, Mississippi; and Vienna, Georgia); Celanese Ltd. (Bishop, 

Texas); and Hexion Specialty Chemicals, Inc. (Baytown, Texas; Demopolis, Alabama; Diboll, Texas; 

Fayetteville, North Carolina; Fremont, California; Geismar, Louisiana; Hope, Arkansas; La Grande, 
FORMALDEHYDE 84

Oregon; Louisville, Kentucky; Missoula, Montana; Riegelwood, North Carolina; Sheboygan, Wisconsin; 

South Glens Falls, New York; and Springfield, Oregon) (SRI 2007). In addition to the above facilities, 

the following companies contributed to the overall U.S. capacity: Capital Resin Corporation (Columbus, 

Ohio); D.B. Western, Inc. (La Porte, Texas); DuPont (Parkersburg, West Virginia); Dynea USA, Inc. 

(Andalusia, Alabama; Moncure, North Carolina; Springfield, Oregon; Toledo, Ohio; and Winnfield, 

Louisiana); GEO Specialty Chemicals, Inc. (Allentown, Pennsylvania); Hercules Inc. (Louisiana, 

Missouri); Perstorp Polyols, Inc. (Toledo, Ohio); Praxair, Inc. (Geismar, Louisiana); and Solutia Inc. 

(Alvin, Texas) (SRI 2007).
FORMALDEHYDE 85

Table 4-1. U.S. Formaldehyde Capacity and Production

Year

Million pounds/year

Capacity Production volume

1960 2,449 1,870

1965 3,556 3,106

1970 Not available 4,427

1975 8,384 4,557

1977 8,830 6,045

1978 9,008 6,499

1982 Not available 4,817

1986 Not available 5,549

1990 9,700 7,500

1992 10,080 8,280

1995 Not available 8,699

1998 11,300 Not available

2000 Not available 10,251

2001 12,500 Not available

2007 11,900 Not available

Sources: C&EN 1994, 1998; CMR 2001; Gerberich et al. 1980; IARC 1995, 2006; SRI 1992, 2007

Table 4-2 lists the facilities in each state that manufacture or process formaldehyde, the intended use, and 

the range of amounts of formaldehyde that are stored on site. The data listed in Table 4-2 are derived 
FORMALDEHYDE 86

from the Toxics Release Inventory (TRI06 2008). Only certain types of facilities were required to report. 

Therefore, this is not an exhaustive list.
FORMALDEHYDE 87

Table 4-2. Facilities that Produce, Process, or Use Formaldehyde

Statea

Number of 

facilities

Minimum 

amount on site 

in poundsb

Maximum 

amount on site 

in poundsb Activities and usesc

AK 5 100,000 9,999,999 1, 2, 3, 4, 5, 7, 9

AL 116 0 499,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14

AR 65 0 9,999,999 1, 2, 3, 4, 5, 6, 7, 8, 10, 11, 12, 13, 14

AZ 17 0 999,999 1, 2, 3, 5, 6, 7, 8, 10, 11, 12

CA 95 0 49,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14

CO 11 0 9,999 1, 2, 5, 6, 7, 10, 11

CT 42 0 99,999,999 1, 2, 3, 5, 6, 7, 8, 10, 11, 12, 14

DE 11 100 999,999 1, 2, 3, 4, 5, 6, 7, 8, 10, 11, 12

FL 34 0 999,999 1, 2, 3, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14

GA 117 0 99,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14

HI 1 10,000 99,999 7

IA 32 0 499,999,999 1, 2, 3, 5, 6, 7, 8, 9, 10, 11, 13, 14

ID 16 0 99,999 1, 2, 3, 5, 6, 8, 10, 11, 13

IL 90 0 499,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14

IN 69 0 49,999,999 1, 2, 3, 4, 5, 6, 7, 8, 10, 11, 12, 13, 14

KS 31 0 9,999,999 1, 2, 3, 5, 6, 7, 8, 9, 10, 11, 12, 13

KY 46 0 9,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14

LA 106 0 10,000,000,000 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14

MA 44 0 9,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12
FORMALDEHYDE 88

Table 4-2. Facilities that Produce, Process, or Use Formaldehyde

Statea

Number of 

facilities

Minimum 

amount on site 

in poundsb

Maximum 

amount on site 

in poundsb Activities and usesc

MD 24 0 999,999 1, 2, 3, 5, 6, 7, 8, 10, 11, 12, 13

ME 40 0 999,999 1, 2, 3, 5, 6, 7, 8, 11, 12, 13, 14

MI 104 0 99,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14

MN 91 0 999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14

MO 50 0 49,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14

MS 49 0 99,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13

MT 24 0 9,999,999 1, 3, 4, 5, 6, 7, 8, 12, 13

NC 136 0 499,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13

ND 5 1,000 99,999 2, 3, 10, 11

NE 9 0 999,999 1, 5, 6, 7, 12, 13

NH 25 0 9,999,999 1, 2, 3, 5, 6, 7, 8, 10, 11, 12

NJ 75 0 99,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14

NM 6 100 9,999,999 1, 3, 4, 6, 7, 8

NV 2 1,000 99,999 6, 7

NY 72 0 499,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13

OH 134 0 99,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14

OK 39 0 49,999,999 1, 2, 3, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14

OR 99 0 499,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14

PA 98 0 99,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14
FORMALDEHYDE 89

Table 4-2. Facilities that Produce, Process, or Use Formaldehyde

Statea

Number of 

facilities

Minimum 

amount on site 

in poundsb

Maximum 

amount on site 

in poundsb Activities and usesc

PR 24 0 9,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14

RI 18 100 999,999 1, 2, 3, 5, 6, 7, 8, 9, 10, 12, 13

SC 112 0 999,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14

SD 9 0 9,999 1, 3, 4, 5, 6, 7, 8, 11, 12, 13, 14

TN 43 0 9,999,999 1, 2, 3, 5, 6, 7, 8, 9, 10, 11, 12, 13

TX 160 0 499,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14

UT 16 0 999,999 1, 3, 5, 6, 7, 8, 10, 11, 12

VA 78 0 9,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14

VT 6 100 99,999 2, 3, 6, 7, 8, 10

WA 58 0 9,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14

WI 96 0 9,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14

WV 47 0 99,999,999 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14

WY 3 0 99,999 1, 2, 3, 5, 7

a

Post office state abbreviations used

b

Amounts on site reported by facilities in each state

c

Activities/Uses: numbers are defined as follows

1. Produce

2. Import

3. Onsite use/processing

4. Sale/Distribution

5. Byproduct

6. Impurity

7. Reactant

8. Formulation Component

9. Article Component

10. Repackaging

11. Chemical Processing Aid

12. Manufacturing Aid 

13. Ancillary/Other Uses

14. Process Impurity

Source: TRI06 2008 (Data are from 2006.)
FORMALDEHYDE 90

Formaldehyde has been manufactured primarily from methanol since the beginning of the 21st century 

(Gerberich and Seaman 2004). Because methanol is manufactured from synthesis gas, usually produced 

from methane, there have been extensive efforts to develop a one-step process that makes formaldehyde 

directly from methanol by partial oxidation. Although a successful commercial process has not been 

developed, a wide range of catalysts and oxidation conditions have been studied (Gerberich and Seaman 

2004). Following World War II, approximately 20% of the production volume in the United States was 

manufactured by vapor phase, non-catalytic oxidation of propane and butanes. This nonselective 

oxidation process produces a variety of coproducts that require a costly and complex separation system, 

and therefore, the methanol process is preferred (Gerberich and Seaman 2004).

Formaldehyde is also produced in solid form as its cyclic trimer, trioxane, and as its polymer, 

paraformaldehyde. As a readily available source of formaldehyde for certain applications, 

paraformaldehyde is prepared commercially by the concentration of aqueous formaldehyde solutions 

under vacuum in the presence of small amounts of formic acid and metal formates. Trioxane is prepared 

commercially by strong acid-catalyzed condensation of formaldehyde in a continuous process (IARC 

2006). Available information indicates that paraformaldehyde is produced in the United States by three 

companies and trioxane is produced by two companies (IARC 2006).

4.2 IMPORT/EXPORT 

In 1999, the import and export volumes were 82 and 21 million pounds, respectively, and in 2000 they 

were 62 and 18 million pounds, respectively (CMR 2001). In 2005, the import and export volumes were 

21 and 27 million pounds, respectively, and in 2006 they were 22 and 31 million pounds, respectively 

(CMR 2007).
FORMALDEHYDE 91

4.3 USE 

The most extensive use of formaldehyde is in the manufacture of urea-formaldehyde, phenolformaldehyde, melamine-formaldehyde resins, and polyacetal resins (IARC 2006). Formaldehyde-based 

resins are used as adhesives and as impregnating resins in the manufacture of particle board, fiber board, 

plywood, furniture, and other wood products. Plywood is the largest market for phenol-formaldehyde 

resins, and particle board is the largest for urea-formaldehyde resins (Gerberich and Seaman 2004). 

These resins are also used for the production of curable moulding materials (appliances, electric controls, 

telephones, wiring services) and as raw materials for surface coatings and controlled release nitrogen 

fertilizers. Additionally, they are used in the textile, leather, rubber, and cement industries. Further uses 

are as binders for foundry sand, stonewool, and glasswool mats in insulating materials, abrasive paper, 

and brake linings (IARC 2006).

Polyacetal plastics produced by polymerization of formaldehyde are incorporated into automobiles to 

reduce weight and fuel consumption. They are also used in the manufacture of functional components of 

audio and video electronics equipment (IARC 2006).

Formaldehyde consumption in the United States in 2005 and 2006 was reported as 10.24 and 

10.50 billion pounds, respectively, and it is projected to be 10.93 billion pounds in 2010 (CMR 2007). 

Formaldehyde consumption in 1999 and 2000 was reported as 9.6 and 9.8 billion pounds, respectively

(CMR 2001; IARC 2006). This was a slight decrease from the 11.3 and 11.6 billion pounds demand 

reported for formaldehyde in 1994 and 1995 (C&EN 1995). The decrease was due to the softening of the 

housing and construction market, a softening that depressed the demand for formaldehyde in urea- and 

phenol-formaldehyde resins used in particle board and plywood, respectively (CMR 2007). Since these 

two classes of thermosetting resins account for more than one-third of formaldehyde consumption, the 

demand for formaldehyde will continue to track the demand in the housing and construction industry 
FORMALDEHYDE 92

(CMR 2001). In 2001, it was reported that the fastest growing formaldehyde market, at about 5% per 

year, in the United States is in the production of acetylenic chemicals (butanediol), MDI, and acetal resins 

(CMR 2001). Table 4-3 shows the distribution of formaldehyde use for select periods between 1963 and 

2007. 
FORMALDEHYDE 93

Table 4-3. Distribution of Formaldehyde Production According to Uses in the 

United States

Percentage of consumption

1963 1969 1972 1977 1989 1998 2001 2007

Phenol-formaldehyde 

resins

22 22 26 25 22 19 16.5 17

Urea-formaldehyde 

resins

21 25 26 25 25 23 24 22

Acetal resins 4 6 7 9 9 11 13 13

Acetylenics (butanediol) NA 2 4 6 11 12 11 9

Melamine resins 6 7 6 5 4 4 3 3

Methylene diisocyanate NA NA NA NA 5 6 7 10

Pentaerythritol 9 7 7 5 7 5 5 5

Hexamethylenetetramine 6 9 6 5 6 4 3 3

Fertilizer 3 3 4 NA 6 4 3.5 3

Trimethylolpropane NA 1.1 1.5 NA NA NA NA NA

Ethylene glycol 12 4 0 0 NA NA NA NA

Miscellaneous 17 14 12 20 5 12 14 15

NA = not available

Sources: C&EN 1989, 1998; CMR 2001, 2007; Gerberich and Seaman 1994; Gerberich et al. 1980.
FORMALDEHYDE 94

4.4 DISPOSAL 

Formaldehyde has been treated by use of biofilters, polymer-coated zeolites, and polymeric membrane, 

but these procedures can be capital- and space-intensive (Cowan et al. 2005). It has been reported that 

formaldehyde generated in the engineered wood industry can potentially be stripped from an air stream in

a fluidized bed containing boiler ash, which can be returned to a boiler to incinerate the formaldehyde. 
FORMALDEHYDE 95

5. POTENTIAL FOR HUMAN EXPOSURE

5.1 OVERVIEW 

Formaldehyde has been identified in at least 29 of the 1,699 hazardous waste sites that have been 

proposed for inclusion on the EPA National Priorities List (NPL) (HazDat 2008). However, the number 

of sites evaluated for formaldehyde is not known. 

In December 2007 and January 2008, the Centers for Disease Control and Prevention (CDC) tested travel 

trailers, park models, and mobile homes provided by the Federal Emergency Management Agency 

(FEMA) as temporary housing to Gulf Coast residents in Louisiana and Mississippi who were displaced 

by Hurricanes Katrina and Rita. The results showed an average indoor air concentration of 77 ppb, with 

measured levels ranging from 3 to 590 ppb; the range is higher than typical background indoor air 

concentrations of 10-30 ppb (CDC 2008). Formaldehyde levels are generally lower in cooler 

temperatures and lower humidity; therefore, levels measured in this study are likely to underestimate 

those that would occur in the summer months (CDC 2008).

5.2 RELEASES TO THE ENVIRONMENT 

The Toxics Release Inventory (TRI) data should be used with caution because only certain types of 

facilities are required to report their releases (EPA 2005). TRI is not an exhaustive list. Manufacturing 

and processing facilities are required to report information to the TRI only if they employ 10 or more fulltime employees; if their facility is included in Standard Industrial Classification (SIC) Codes 10 (except 
FORMALDEHYDE 96

1011, 1081, and 1094), 12 (except 1241), 20–39, 4911 (limited to facilities that combust coal and/or oil 

for the purpose of generating electricity for distribution in commerce), 4931 (limited to facilities that 

combust coal and/or oil for the purpose of generating electricity for distribution in commerce), 4939 

(limited to facilities that combust coal and/or oil for the purpose of generating electricity for distribution 

in commerce), 4953 (limited to facilities regulated under RCRA Subtitle C, 42 U.S.C. section 6921 et 

seq.), 5169, 5171, and 7389 (limited S.C. section 6921 et seq.), 5169, 5171, and 7389 (limited to facilities 

primarily engaged in solvents recovery services on a contract or fee basis); and if their facility produces, 

imports, or processes ≥25,000 pounds of any TRI chemical or otherwise uses >10,000 pounds of a TRI 

chemical in a calendar year (EPA 2005).

5.2.1 Air 

Estimated releases of 8.88 million pounds (~4,028 metric tons) of formaldehyde to the atmosphere from 

725 domestic manufacturing and processing facilities in 2006 accounted for about 41% of the estimated 

total environmental releases from facilities required to report to the TRI (TRI06 2008). These releases are 

summarized in Table 5-1.
FORMALDEHYDE 97

Table 5-1. Releases to the Environment from Facilities that Produce, Process, or 

Use Formaldehydea

Reported amounts released in pounds per yearb

Statec RFd Aire Waterf UI

g Landh Otheri

Total release

On-sitej Off-sitek

On- and offsite

AK 1 3,871 0 0 250 0 3,871 250 4,121

AL 37 417,877 37,125 0 2,125 0 455,597 1,530 457,127

AR 15 292,714 19,719 0 1,012 0 312,483 963 313,446

AZ 4 9,813 No data 0 167 0 9,813 167 9,980

CA 26 196,556 10 0 3,267 750 197,263 3,320 200,583

CO 1 0 No data 0 0 0 0 0 0

CT 5 21,647 1,078 0 2,230 1,096 22,725 3,326 26,051

DE 1 1,965 0 0 0 0 1,965 0 1,965

FL 15 295,914 19,431 89,497 423 0 405,265 0 405,265

GA 35 795,077 19,572 0 1,317 805 814,677 2,094 816,771

IA 16 156,218 4,554 10,868 5 0 160,772 10,873 171,645

ID 1 25,410 5,600 0 0 0 31,010 0 31,010

IL 32 59,702 2,818 0 5,662 518 62,520 6,180 68,700

IN 13 74,451 No data 0 19,402 1,550 74,451 20,952 95,403

KS 11 112,150 0 0 201 0 112,150 201 112,351

KY 14 40,966 6,018 0 0 0 46,984 0 46,984

LA 32 394,829 28,805 10,818,233 19,874 0 11,257,892 3,849 11,261,741

MA 10 53,737 6,490 0 1,336 377 60,227 1,713 61,940
FORMALDEHYDE 98

Table 5-1. Releases to the Environment from Facilities that Produce, Process, or 

Use Formaldehydea

Reported amounts released in pounds per yearb

Statec RFd Aire Waterf UI

g Landh Otheri

Total release

On-sitej Off-sitek

On- and offsite

MD 4 22,113 No data 0 0 0 22,113 0 22,113

ME 8 236,773 5,693 0 766 0 242,481 751 243,232

MI 26 144,342 1,837 9 65,194 9 146,182 65,209 211,391

MN 12 121,667 0 0 8 0 121,675 0 121,675

MO 12 34,045 311 0 9,541 0 34,361 9,536 43,897

MS 11 311,085 2,539 0 239 0 313,624 239 313,863

MT 4 591,312 60 0 45 0 591,414 3 591,417

NC 42 503,529 31,057 0 16,581 776 536,450 15,493 551,943

NE 7 49,763 0 0 5 0 49,768 0 49,768

NH 2 2,808 128 0 1 0 2,936 1 2,937

NJ 10 2,564 0 0 32 0 2,596 0 2,596

NV 1 0 No data 0 0 0 0 0 0

NY 19 80,795 27,272 0 480 5,105 108,179 5,473 113,652

OH 39 397,719 1,160 235,776 98,696 0 466,416 266,935 733,351

OK 8 184,179 1,837 0 5 0 186,021 0 186,021

OR 27 873,071 10,970 0 1,511 0 884,047 1,505 885,552

PA 26 371,071 3,875 0 5,263 43 374,959 5,293 380,252

PR 2 1,161 No data 0 0 2,617 1,161 2,617 3,777
FORMALDEHYDE 99

Table 5-1. Releases to the Environment from Facilities that Produce, Process, or 

Use Formaldehydea

Reported amounts released in pounds per yearb

Statec RFd Aire Waterf UI

g Landh Otheri

Total release

On-sitej Off-sitek

On- and offsite

RI 3 15 No data 0 0 0 15 0 15

SC 33 682,966 31,124 0 23,447 0 719,275 18,262 737,537

SD 2 42,541 No data 0 0 0 42,541 0 42,541

TN 12 88,806 13,563 0 562 161 102,369 723 103,092

TX 68 561,366 6,079 808,681 14,573 2,216 1,371,887 21,028 1,392,915

UT 3 8,081 No data 0 28 48 8,081 76 8,157

VA 15 166,330 971 0 2,672 0 168,611 1,362 169,974

VT 1 253 No data 0 20 0 253 20 273

WA 13 147,481 32,723 0 973 90 180,204 1,063 181,267

WI 32 140,158 7,721 0 5,394 5 152,839 439 153,278

WV 12 84,897 555 0 229 0 85,456 225 85,681

WY 2 75,715 No data 0 0 0 75,715 0 75,715

Total 725 8,879,500 330,696 11,963,064 303,537 16,166 21,021,291 471,671 21,492,962
FORMALDEHYDE 100

Table 5-1. Releases to the Environment from Facilities that Produce, Process, or 

Use Formaldehydea

Reported amounts released in pounds per yearb

Statec RFd Aire Waterf UI

g Landh Otheri

Total release

On-sitej Off-sitek

On- and offsite

a

The TRI data should be used with caution, since only certain types of facilities are required to report. TRI is not an 

exhaustive list. Data are rounded to nearest whole number.

b

Data in TRI are maximum amounts released by each facility.

c

Post office state abbreviations are used.

d

Number of reporting facilities.

e

The sum of fugitive and point source releases are included in releases to air by a given facility. f

Surface water discharges, waste water treatment (metals only), and publicly owned treatment works (POTWs) (metal 

and metal compounds).

g

Class I wells, Class II-V wells, and underground injection. h

Resource Conservation and Recovery Act (RCRA) subtitle C landfills; other on-site landfills, land treatment, surface 

impoundments, other land disposal, other landfills.

i

Storage only, solidification/stabilization (metals only), other off-site management, transfers to waste broker for 

disposal, unknown

j

The sum of all releases of the chemical to air, land, water, and underground injection wells.

k

Total amount of chemical transferred off-site, including to POTWs.

RF = reporting facilities; UI = underground injection

Source: TRI06 2008 (Data are from 2006)

“Clean” fuels such as natural gas can also produce significant levels of formaldehyde (Dasgupta et al. 

2005). In large-bore gas turbine engine exhaust, the ratio of formaldehyde to total hydrocarbons in the 

exhaust is about 1–2.5%. Exhaust from internal combustion engines powered by sludge digester gas 

contains formaldehyde levels of 50-200 ppm. Formaldehyde generation is also an issue with the clean 

power generation technologies of the future. Methanol-based fuel cells, which many regard as ultimately 

more practical than hydrogen fuel cells, can produce substantial amounts of formaldehyde (Dasgupta et 

al. 2005).
FORMALDEHYDE 101

There is a potential for release of formaldehyde to air from hazardous waste sites. Formaldehyde has 

been detected in air samples collected at 6 of the 29 hazardous waste sites where formaldehyde has been 

detected in some environmental media (HazDat 2008).

Some materials used to construct and finish the interiors of new houses emit formaldehyde. The 

emissions of formaldehyde from these materials can result in substantial contamination of indoor air. In 

the past, elevated concentrations of formaldehyde in newly manufactured homes were a result of 

emissions from engineered wood products. An understanding of the problem led to the development of 

test methods and the establishment of guidelines for the emissions of formaldehyde from wood products 

by the U.S. Department of Housing and Urban Development. Today, the emissions of formaldehyde 

from wood products are substantially lower (Hodgson et al. 1999). Specific emission rates of 

formaldehyde measured in 1997 and 1998 in four newly manufactured homes in Plant City, Florida, 

several of which had incorporated interior finish materials with lower volatile organic compound (VOC) 

emissions and one of which had a modified ventilation system, had a median value of 41 μg/m2

/hour, and 

all the emission rates measured were <70 μg/m2

/hour (Hodgson et al. 1999). These emission rates are 

generally consistent with the formaldehyde emission rates measured for various engineered wood 

products (Hodgson et al. 1999). Formaldehyde emission rates reported in a study of four new 

manufactured houses sampled over 2-9.5 months after installation and seven new site built houses 

sampled 1–2 months after completion in 1997 and 1998 were 29–68 and 10–58 μg/m2

/hour, respectively 

(Hodgson et al. 2000). Construction materials that were identified as major sources of formaldehyde 

included plywood flooring, latex paint, and sheet vinyl flooring. A plywood specimen used in the 

construction of these houses had an emission rate of 29 μg/m2

/hour after 72 hours of exposure (Hodgson 

et al. 2000). In a study measuring emission rates in a new, unoccupied manufactured house in 

Gaithersburg, Maryland over the course of 1 year (August 2002–September 2003), formaldehyde 

emission rates ranged from 34 to 121 μg/m2

/hour (DOE 2004).
FORMALDEHYDE 102

Newly manufactured structural insulated panels obtained in March 2003 from two separate manufacturers 

and measured at 1 and 4 months had formaldehyde emission rates of 4.8 and <3 μg/m2

/hour, respectively 

(DOE 2003).

Measured formaldehyde emission rates from low nitrogen oxide-emitting, unflued gas heaters ranged 

from <0.1 to 2.5 ng/Joule (Brown et al. 2004).

5.2.2 Water 

Estimated releases of 0.33 million pounds (~150 metric tons) of formaldehyde to surface water and to 

publicly owned treatment works (POTWs) from 725 domestic manufacturing and processing facilities in 

2006 accounted for about 1.5% of the estimated total environmental releases from facilities required to 

report to the TRI (TRI06 2008). These releases are summarized in Table 5-1.

There is a potential for release of formaldehyde to water from hazardous waste sites. Formaldehyde has 

been detected in surface water samples collected at 6 of the 29 hazardous waste sites and in groundwater 

samples collected at 4 of the 29 hazardous waste sites where formaldehyde has been detected in some 

environmental media (HazDat 2008).

5.2.3 Soil 

Estimated releases of 0.30 million pounds (~138 metric tons) of formaldehyde to soils from 725 domestic 

manufacturing and processing facilities in 2006 accounted for about 1.4% of the estimated total 

environmental releases from facilities required to report to the TRI (TRI06 2008). An additional 

11.96 million pounds (~5,426 metric tons), constituting about 56% of the total environmental emissions, 

were released via underground injection (TRI06 2008). These releases are summarized in Table 5-1.
FORMALDEHYDE 103

Formaldehyde may be directly released to soil during agricultural application as a fumigant fungicide or a

bactericide (Tomlin 2003).

There is a potential for the release of formaldehyde to soil from hazardous waste sites. Formaldehyde has 

been detected in soil samples collected at 1 of the 29 hazardous waste sites and in sediment samples 

collected at 1 of the 29 hazardous waste sites where formaldehyde has been detected in some 

environmental media (HazDat 2008).

5.3 ENVIRONMENTAL FATE 

5.3.2.1 Air 

Formaldehyde reacts with the NO3 radical by H-atom extraction with a lifetime of 83 days, assuming a 

12-hour average nighttime NO3 radical concentration of 5x108 molecules per cm3 (Atkinson and Arey 

2003).

5.3.2.3 Sediment and Soil 

The fate of formaldehyde in soil is not fully understood, but it is biodegradable to carbon dioxide and 

water or formic acid under both aerobic and anaerobic conditions. It is also biologically active, reacting

readily with phenol, amine, amide, sulfide, purine, and pyrimidine functional groups, each of which can 

be found in soil humic substances. Further, formaldehyde is subject to spontaneous polymerization,

forming units of paraformaldehyde (Cooke et al. 2003).
FORMALDEHYDE 104

In a study investigating chemical interactions with soil humic substances by use of co-elution of 

radiolabelled compounds with gel filtration chromatography-separated humic substance fractions, results 

suggested a direct association of free formaldehyde with low molecular weight humic substances (Cooke 

et al. 2003). This study also suggested that the degree of binding of formaldehyde to the humic 

substances became more stable over time (Cooke et al. 2003).

5.4 LEVELS MONITORED OR ESTIMATED IN THE ENVIRONMENT 

5.4.1 Air 

The main source of formaldehyde in the atmosphere is believed to be photochemical oxidation of 

hydrocarbon combustion products. As much as 88% of formaldehyde in urban air is thought to be 

photochemically derived (Austin 2003).

Dasgupta et al. (2005) measured summertime ambient formaldehyde levels in a study of five major U.S. 

cities: Nashville, Tennessee (June–July 1999); Atlanta, Georgia (August 1999); Houston, Texas 

(August–September 2000); Philadelphia, Pennsylvania (June–July 2001); and Sydney, Florida (April–

June 2002). Reported concentration ranges were 1.43–12.67 ppb (mean 5.05 ppb) in Nashville, 0.42–

18.25 ppb (mean 7.96 ppb) in Atlanta, 0.15–47.13 ppb (mean 4.49 ppb) in Houston, 0.33–9.53 ppb (mean 

3.12 ppb) in Philadelphia, and 0.37–9.38 ppb (mean 2.63 ppb) in Sydney. It was shown that land-sea 

breeze circulations played an important role in observed concentrations in coastal cities, and clear diurnal 

patterns were observed at all the sites (Dasgupta et al. 2005).

Multimedia sampling at a subset of Arizona homes participating in EPA’s National Human Exposure 

Assessment Survey was conducted in order to assess residential environmental exposure to volatile 

organic compounds (Gordon et al. 1999). Formaldehyde was found in 69% of the indoor air samples 
FORMALDEHYDE 105

collected, with a median concentration of 17 ppb (21 μg/m3) and 21% of the outdoor air samples 

collected had a median concentration of 5.1 ppb (6.3 μg/m3

).

The median formaldehyde concentration measured in 1997 and 1998 in four newly manufactured homes 

in Plant City, Florida, several of which had incorporated interior finish materials with lower VOC 

emissions and one of which had a modified ventilation system, was reported as 37 ppb, and all the 

concentrations were <50 ppb (DOE 1999). A mean indoor air formaldehyde concentration of 40 ppb was 

reported in a study of four new manufactured houses sampled over 2-9.5 months after those houses were

installed and of seven new site-built houses sampled 1-2 months after completion in 1997 and 1998 

(Hodgson et al. 2000). Formaldehyde concentrations ranged from 21 ppb - 47 ppb in the manufactured 

houses and from 14 -58 ppb in the site-built houses. Major identified sources of formaldehyde included 

plywood flooring, latex paint, and sheet vinyl flooring. In a study measuring indoor air in a new, 

unoccupied manufactured house in Gaithersburg, Maryland over the course of 1 year (August 2002–

September 2003), formaldehyde concentrations exhibited temporal variability ranging from 20 ppb -104 

ppb (25 - 128 μg/m3

) with the lowest concentrations occurring in winter months when indoor relative 

humidity was low (DOE 2004).

In December 2007 and January 2008, CDC tested travel trailers, park models, and mobile homes provided 

by FEMA as temporary housing to Gulf Coast residents in Louisiana and Mississippi, residents who were 

displaced by Hurricanes Katrina and Rita. The results showed an average indoor air concentration of 

77 ppb, with measured levels ranging from 3 to 590 ppb, a range higher than typical background indoor 

air concentrations of 10–30 ppb. Formaldehyde levels are generally lower in cooler temperatures and 

lower humidity; therefore, levels measured in this study are likely to underestimate those that would occur 

in the summer months (CDC 2008).
FORMALDEHYDE 106

Levels of formaldehyde in conventional homes and workplaces housing nonsmokers ranged from 0.03 to 

0.06 mg/m3 (0.02–0.05 ppm), while it ranged from 0.05 to 0.35 mg/m3 (0.04–0.28 ppm) in homes and 

workplaces containing environmental tobacco smoke (WHO 2000).

5.4.2 Water 

Synthetic resin-producing industries generate waste water with high levels of organic matter, including 

formaldehyde as a major component. Formaldehyde has been measured in these waste waters at 

concentrations ranging from 7 to 2,711 mg/L (Eiroa et al. 2005).

5.4.4 Other Environmental Media 

Formaldehyde was detected in commercial 2% and fresh whole milk of cows fed on a typical North 

American dairy diet, with average concentrations of 0.164 and 0.027 mg/kg, respectively (Kaminski et al.

1993). Available data suggest that the highest concentrations of formaldehyde naturally occurring in 

foods (up to 60 mg/kg) are in some fruits and marine fish (Environment Canada/Health Canada 2001). 

Maple syrup collected from maple trees that had been implanted with paraformaldehyde to deter bacterial 

growth in tap holes contained a maximum formaldehyde concentration of 14 mg/kg, whereas syrup from 

untreated trees had a concentration of <1 mg/kg (Environment Canada/Health Canada 2001). 

Formaldehyde concentrations of 3.4 and 4.5 mg/kg in brewed coffee and 10 and 16 mg/kg in instant 

coffee have been reported (Hayashi et al. 1986).

Mansfield et al. (1977) used liquid chromatography to measure formaldehyde as a combustion product in 

tobacco smoke from six different brands of American filter tip cigarettes. The average amount of 

formaldehyde by brand ranged from 45.2 to 73.1 μg/ per cigarette and from 5.1 to 8.9 μg/ per puff. 

Triebig and Zober report that the level of formaldehyde in side stream cigarette smoke is 50 times higher 
FORMALDEHYDE 107

than main stream smoke (Triebig and Zober 1984), while the National Research Council put the value at 

5–8 times more formaldehyde in side stream smoke (NRC 1986).

Formaldehyde is sometimes used as a biocide in finger-paints, and it has been detected in finger-paints at 

concentrations of 441–793 ppm (mg/kg) (Garrigos et al. 2001).

5.5 GENERAL POPULATION AND OCCUPATIONAL EXPOSURE 

The contribution of various atmospheric environments to the average exposure to formaldehyde is given 

in Table 5-2 (WHO 2000).
FORMALDEHYDE 108

Table 5-2. The Contribution of Various Atmospheric Environments to the 

Average Exposure to Formaldehyde

Source mg/day

Air

Outdoor air (10% of time) 0.002–0.04

Indoor air

Home (65% of time)

Conventional

Mobile home

Environmental tobacco smoke

0.3–0.6

1.0

0.5–3.5

Workplace (25% of time)

Without occupational exposure

With occupational exposure

Environmental tobacco smoke

0.2–0.5

8.0

0.4–2.8

Smoking (20 cigarettes/day) 0.9–2.0

Source: WHO 2000

In 13 healthy adult volunteers aged 24–50 years old, formaldehyde was detected in all urine samples 

collected from 9 men and 4 women at background concentrations of 56.85–70.57 and 60.84–144.57 μg/L, 

respectively (Takeuchi et al. 2007). The median observed formaldehyde levels in the urine of the men 

and women were 62.10 and 79.30 μg/L, respectively. Formaldehyde was detected at concentrations 

ranging from 1,230 to 72,729 ppb in exhaled breath samples collected from 344 adult volunteers having a 

mean age of 61.6 years. The median observed formaldehyde level detected in exhaled breath samples 

was 4.263 ppb (Moser et al. 2005).
FORMALDEHYDE 109

5.7 POPULATIONS WITH POTENTIALLY HIGH EXPOSURES 

Formaldehyde concentrations in mobile homes may be up to 14 times higher than in conventional homes

(Gammage and Hawthorne 1985; Hawthorne et al. 1986). Gulf Coast residents in Louisiana and 

Mississippi who were displaced by Hurricanes Katrina and Rita and were provided travel trailers and 

mobile homes as temporary housing by FEMA have been exposed to higher-than-normal formaldehyde 

levels. The average indoor air concentration measured in the study of this housing was 77 ppb (CDC 

2008). 

Smokers and persons who live in a home with a cigarette smoker also may be exposed to higher levels of 

formaldehyde. Environmental tobacco smoke, which is a combination of diluted sidestream smoke 

released from a cigarette’s burning end and mainstream smoke exhaled by an active smoker, can 

contribute 10–25% (0.1–1 mg/day) of the total average indoor exposure to formaldehyde (WHO 1986).

5.8.2 Ongoing Studies 

The Federal Research in Progress (FEDRIP 2008) database provides additional information obtainable 

from a few ongoing studies. These studies may fill in some of the data needs identified in Section 6.8.1. 

The studies are summarized in Table 5-3.
FORMALDEHYDE 110

Table 5-3. Ongoing Studies on Formaldehyde

Investigator Affiliation Research description Sponsor

Faloona, Ian C University of 

California, Davis

Researchers are conducting a study of gas 

phase formaldehyde in a forested environment 

and the photochemical oxidation of 

hydrocarbons. The goals of this study are to 

better understand the atmospheric processing of 

VOCs and their concurrent formaldehyde 

production.

National Science 

Foundation

Kretzschmar, 

Ilona

CUNY City 

College

This study describes a method for the 

generation of porous, cylindrical polymer 

membranes with a uniform catalyst coating that 

will lead to the development of new material for 

the separation and decomposition of 

formaldehyde in indoor air streams.

National Science 

Foundation

Marotta, 

Christopher L

Eltron Research, 

Inc.

Researchers are conducting a study to develop 

a small, inexpensive sensor for measuring the 

concentration of formaldehyde in real-time in 

order to protect workers who encounter 

formaldehyde in the chemical industry. The aim 

is also to create a sensor platform that can be 

readily adapted for indoor air quality or 

environmental monitoring applications.

NIOSH

CUNY = City University of New York; NIOSH = National Institute for Occupational Safety and Health; VOC = volatile 

organic compound

Source: FEDRIP 2008 

As previously discussed, in the aftermath of Hurricanes Katrina and Rita, the Federal Emergency 

Management Agency (FEMA) provided travel trailers, park models, and mobile homes to displaced Gulf 

Coast residents who had lost their homes. Residents of these trailers and mobile homes have raised 

concerns about air quality in the trailers and the occurrence of respiratory and other symptoms resulting 
FORMALDEHYDE 111

from exposure to formaldehyde. The Centers for Disease Control and Prevention’s (CDC’s) National 

Center for Environmental Health (NCEH) has been working with FEMA to investigate the health 

concerns of those living in the trailers and mobile homes and to take action to protect residents’ health. In 

December 2007 and January 2008, CDC tested travel trailers, park models, and mobile homes provided 

by FEMA as temporary housing to Gulf Coast residents in Louisiana and Mississippi who were displaced 

by hurricanes Katrina and Rita (CDC 2008). The study aimed to determine formaldehyde levels in 

occupied trailers, determine trailer characteristics that could affect formaldehyde levels, and provide 

information to assist FEMA in deciding whether to relocate residents from FEMA-supplied trailers in the 

Gulf Coast area. The findings of this study have been addressed in an official CDC Press Release found 

on the CDC/NCEH Website at http://www.cdc.gov/nceh/ehhe/trailerstudy/residents.htm#final. 

A new survey, NHANES IV, is in the process of being conducted by CDC.
FORMALDEHYDE 112

6. ANALYTICAL METHODS

6.1 BIOLOGICAL MATERIALS 

Takeuchi et al. (2007) developed a technique for quantifying formaldehyde in urine by derivatization with 

O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) to the PFBHA-formaldoxime, using a 

headspace sampler coupled to a gas chromatograph equipped with an electron capture detector (ECD) 

(see Table 6-1).

Table 6-1. Analytical Methods for Determining Formaldehyde in Biological 

Materials

Sample matrix Preparation method

Analytical 

method

Sample

detection 

limit

Percent 

recovery Reference

Urine Derivatization with 

O-(2,3,4,5,6-

pentafluorobenzyl)-

hydroxylamine.

GC/EC 1.08 μg/L 99 Takeuchi et al. 

2007

GC/EC = gas chromatography/electron capture

6.2 ENVIRONMENTAL SAMPLES 

The most widely used methods for the determination of the concentration of formaldehyde in air are 

based on ultraviolet/visible (UV/VIS) spectrophotometry measurements of the absorption band at 580 nm 

following derivitization with chromotropic and sulfuric acid. Sensitivities of 0.01–0.03 mg/m3 can be 

achieved by use of these methods. Other methods include colorimetry, fluorimetry, high-performance 

liquid chromatography (HPLC), polarography, gas chromatography (GC), infrared detection, and gas 
FORMALDEHYDE 113

detector tubes. Most methods require the formation of a formaldehyde derivative for separation and 

detection (IARC 2006). Formaldehyde determination by use of HPLC can achieve a limit of detection of 

≤2 μg/m3

, and HPLC is the most sensitive method. Gas detection tubes that have sensitivities of about 

0.05–0.12 μg/m3 (0.04–0.1 ppm) and infrared analyzers that have sensitivities of about 1.2–230 μg/m3 (1–

110 ppb) are often used to monitor workplace atmospheres (IARC 2006). 

One type of passive sampler uses a glass fiber filter or a tape impregnated with 2,4-

dinitrophenylhydrazine (DNPH) and phosphoric acid mounted in a polystyrene cassette (see Table 6-2). 

SKC Inc. and GMD Systems use this passive sampling method for commercially available badges (Levin 

and Lindahl 1994; Levin et al. 1989). 

Table 6-2. Analytical Methods for Determining Formaldehyde in Environmental 

Samples

Sample 

matrix Preparation method

Analytical 

method

Sample 

detection limit

Percent 

recovery Reference

Air Preparation of passive 

monitor, formaldehyde in 

air adsorbs onto DNPH 

and sulfuric acid 

impregnated glass fiber 

filter or tape

UV/VIS

absorbance 

at 365 nm

6 μg/m3 (5 ppb) 

(8 hours)

1.2 μg/m3

(1 ppb) 

(24 hours)

100%

(5% RSD)

Levin and Lindahl 

1994; Levin et al. 

1989

Air Drawing of air through a 

sampling tube containing 

silica gel coated with 

DNPH. Elution of 

derivative with 

acetonitrile. 

GC/NPD 0.12 μg/sample >95 Jeong and Paik 

2005
FORMALDEHYDE 114

Table 6-2. Analytical Methods for Determining Formaldehyde in Environmental 

Samples

Sample 

matrix Preparation method

Analytical 

method

Sample 

detection limit

Percent 

recovery Reference

Atmospheric 

water

Reaction of 

formaldehyde in water 

with ammonium acetate 

and 2,4-pentanedione in 

FIA system to form 

3,5-diacetyl-1,4-dihydrolutidine.

FIA/fluorescence

3 μg/L 

(3 ppb)

No data Dong and Dasgupta 

1987

DNPH = 2,4-dinitrophenylhydrazine; FIA = flow injection analysis; GC = gas chromatography; NPD =nitrogenphosphorus detector; RSD = relative standard deviation; UV/VIS = ultraviolet/visible absorbance detection

Jeong and Paik (2005) have reported a method in which the DNPH formaldehyde derivatives are analyzed

by use of GC equipped with a nitrogen-phosphorus detector (GC-NPD) in order to measure personal 

exposure in the workplace. In laboratory tests, this new method, referred to as the GC-NPD method, is as 

sensitive as the NIOSH analytical method, which uses HPLC equipped with an ultraviolet detector (Jeong 

and Paik 2005). 

The method of Dong and Dasgupta (1987) relies on the reaction of formaldehyde in atmospheric water 

with a diketone (2,4-pentanedione) and ammonium acetate to form a fluorescent derivative that is 

measured spectrophotometrically in a flow injection analysis system.
FORMALDEHYDE 115

6.3 ADEQUACY OF THE DATABASE 

6.3.2 Ongoing Studies 

The information in Table 6-3 was found as a result of a search of the Federal Research in Progress 

database (FEDRIP 2008). 

The Environmental Health Laboratory Sciences Division of the National Center for Environmental 

Health, Centers for Disease Control and Prevention, is developing methods for the analysis of 

formaldehyde and other volatile organic compounds in blood. These methods use purge and trap 

methodology, high-resolution gas chromatography, and magnetic sector mass spectrometry, which give 

detection limits in the low parts per trillion (ppt) range. 

Table 6-3. Ongoing Studies on Formaldehyde

Investigator Affiliation Research description Sponsor

Kretzschmar, 

Ilona

CUNY City 

College

This study describes a method for the 

generation of porous, cylindrical polymer 

membranes with a uniform catalyst coating 

that will lead to the development of new 

material for the separation and decomposition 

of formaldehyde in indoor air streams.

National Science 

Foundation

Marotta, 

Christopher L

Eltron Research, 

Inc.

Researchers are conducting a study to 

develop a small, inexpensive sensor for 

measuring the concentration of formaldehyde 

in real-time in order to protect workers who 

encounter formaldehyde in the chemical 

industry. The aim is also to create a sensor 

platform that can be readily adapted for 

indoor air quality or environmental monitoring 

applications.

NIOSH

CUNY = City University of New York; NIOSH = National Institute for Occupational Safety and Health

Source: FEDRIP 2008 
FORMALDEHYDE 116

7. REGULATIONS, ADVISORIES, AND GUIDELINES

The EPA oral reference dose (RfD) for formaldehyde is 0.2 mg/kg/day for causing gastrointestinal 

damage (IRIS 2010). EPA began a reassessment of the inhalation reference concentration (RfC) in 

January 1998, and a draft assessment was released for public comment in June 2010. A committee of the 

NRC is conducting an independent scientific review of this EPA draft human health assessment of 

formaldehyde for IRIS (IRIS 2010). The committee will provide a brief report that comments on EPA’s 

identification of potential adverse non-cancer health effects, assessment of carcinogenic potential,

exposure-response analysis for identified end points, quantitative risk assessment methods, and evaluation 

of sources of uncertainty in the health assessment.

The international and national regulations, advisories, and guidelines regarding formaldehyde in air, 

water, and other media are summarized in Table 7-1. 

The National Toxicology Program (NTP) (2005) noted that formaldehyde is reasonably anticipated to be 

a human carcinogen. NTP has included formaldehyde as an item under consideration for the Twelfth 

Report on Carcinogens (NTP 2008, 2010). In 2006, the International Agency for Research on Cancer 

(IARC) has reclassified formaldehyde from Group 2A to Group 1 (IARC 2008). The EPA has classified 

formaldehyde as a B1 compound, probable human carcinogen, on the basis of limited evidence in humans 

and sufficient evidence in animals (IRIS 2010).

Formaldehyde is on the list of chemicals subject to the requirements of The Emergency Planning and 

Community Right-to-Know Act of 1986 (EPCRA) (EPA 2008c). Section 313 of Title III of EPCRA 

requires owners and operators of certain facilities that manufacture, import, process, or otherwise use the 
FORMALDEHYDE 117

chemicals on this list to report annually their release of those chemicals to any environmental media (EPA 

2008c). 

OSHA requires employers of workers who are occupationally exposed to formaldehyde to institute 

engineering controls and work practices to reduce and maintain employee exposure at or below 

permissible exposure limits (PELs). The employer must use controls and practices, if feasible, to reduce 

exposure to or below an 8-hour time-weighted average (TWA) of 0.75 ppm. The 15-minute, short-term 

exposure limit (STEL) for formaldehyde is 2 ppm (OSHA 2007b).

The EPA regulates formaldehyde under the Clean Air Act (CAA) and has designated formaldehyde as a 

hazardous air pollutant (HAP) (EPA 2008c); formaldehyde is listed among the urban HAPs for the 

Integrated Urban Air Toxics Strategy (EPA 1999). The major source category for which formaldehyde 

emissions are controlled is the Synthetic Organic Chemicals Manufacturing Industry (SOCMI) (EPA 

2008e, 2008i).

Under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), 

owners of vessels or facilities are required to immediately report release of formaldehyde equal to or 

greater than the reportable quantity of 100 pounds (45.4 kg) (EPA 2008c).

The Food and Drug Administration (FDA) identifies formaldehyde as an indirect food additive for use 

only as a component of adhesives (FDA 2007b). When used in accordance with specified conditions, the 

food additive, formaldehyde, is permitted in feed and drinking water of animals (FDA 2007a).
FORMALDEHYDE 118

Table 7-1. Regulations, Advisories, and Guidelines Applicable to Formaldehyde

Agency Description Information Reference

INTERNATIONAL

Guidelines:

IARC Carcinogenicity classification Group 1a IARC 2008

WHO Air quality guidelinesb 0.1 mg/m3 WHO 2000

Drinking water quality guidelines 0.9 mg/L WHO 2004

NATIONAL

Regulations and 

Guidelines:

a. Air

ACGIH TLV (ceiling limit) 0.3 ppm ACGIH 2007

TLV basis (critical effects)c Upper respiratory tract 

and eye irritation

AIHA ERPG-1d 1 ppm AIHA 1988

ERPG-2d 10 ppm

ERPG-3d 25 ppm

EPA AEGL-1e EPA 2007a

10 minutes 0.90 mg/m3

30 minutes 0.90 mg/m3

60 minutes 0.90 mg/m3

4 hours 0.90 mg/m3

8 hours 0.90 mg/m3

AEGL-2e

10 minutes 14 mg/m3

30 minutes 14 mg/m3

60 minutes 14 mg/m3

4 hours 14 mg/m3

8 hours 14 mg/m3

AEGL-3e

10 minutes 100 mg/m3

30 minutes 70 mg/m3

60 minutes 56 mg/m3

4 hours 35 mg/m3

8 hours 35 mg/m3

Second list of AEGL priority chemicals Yes EPA 2008a
FORMALDEHYDE 119

Table 7-1. Regulations, Advisories, and Guidelines Applicable to Formaldehyde

Agency Description Information Reference

for guideline development

Hazardous air pollutant (HAP) Yes EPA 2007b

42 USC 7412

Listed on the Urban HAPs for the 

Integrated Urban Air Toxics Strategy

Yes EPA 1999

64 FR 38706

NATIONAL (cont.)

National emission standards for 

organic hazardous air pollutants from 

the SOCMI

Yes EPA 2008i

40 CFR 68.107, 

Table 2

EPA Regulated toxic substances and 

threshold quantities for accidental 

release prevention under Section 

112(r) of the Clean Air Act

15,000 pounds EPA 2008g

40 CFR 68.130

Standards of performance for 

equipment leaks of VOC in SOCMI

Yes EPA 2008e

40 CFR 68.489

NIOSH REL (10-hour TWA) 0.016 ppm NIOSH 2005

Ceiling limit (15-minute) 0.1 ppm

IDLH 20 ppm

Target organs Eyes and respiratory 

system

Potential occupational carcinogen Yes

Category of pesticides Group 1 pesticidef NIOSH 1992

OSHA PEL (8-hour TWA) for general, 

shipyard, and construction industry 

(ceiling limit)

0.75 ppm OSHA 2007b

29 CFR 

1910.1048

STEL (15-minute) 2 ppm

Highly hazardous chemical which 

present a potential for a catastrophic 

event or above the threshold quantity

Yes OSHA 2007a

29 CFR 1910.119

Threshold quantity 1,000 pounds

b. Water

EPA Designated as hazardous substances 

in accordance with Section 

311(b)(2)(A) of the Clean Water Act

Yes EPA 2008b

40 CFR 116.4

Drinking water standards and health EPA 2006a
FORMALDEHYDE 120

Table 7-1. Regulations, Advisories, and Guidelines Applicable to Formaldehyde

Agency Description Information Reference

advisories

1-day health advisory for a 

10-kg child

10 mg/L

10-day health advisory for a 

10-kg child

5 mg/L

DWEL 7 mg/L

Lifetime 1 mg/L

National primary drinking water 

standards

No data EPA 2003

National recommended water quality 

criteria

No data EPA 2006b

Reportable quantities of hazardous 

substances designated pursuant to 

Section 311 of the Clean Water Act

100 pounds EPA 2008d

40 CFR 117.3

NATIONAL (cont.)

c. Food

FDA EAFUSg Yes FDA 2008

Indirect food additives: adhesives and 

components of coatings

Yes FDA 2007b

21 CFR 175.105

Food additive permitted in feed and 

drinking water of animals

Yes FDA 2007a

21 CFR 573.460

d. Other

ACGIH Carcinogenicity classification A2h ACGIH 2007

EPA Carcinogenicity classification Group B1i IRIS 2010

RfC Under review

RfD 0.2 mg/kg/day

Master Testing List Yesj EPA 2008h

Superfund, emergency planning, and 

community right-to-know

Designated CERCLA hazardous 

substance

Yesk EPA 2008c

40 CFR 302.4

Reportable quantity 100 pounds

Effective date of toxic chemical 

release reporting

01/01/1987 EPA 2008j

40 CFR 372.65

Extremely Hazardous Substances EPA 2008f

Reportable quantity 40 CFR 355, 100 pounds
FORMALDEHYDE 121

Table 7-1. Regulations, Advisories, and Guidelines Applicable to Formaldehyde

Agency Description Information Reference

Threshold planning quantity 500 pounds Appendix A

Identification and listing of hazardous 

waste

EPA 2008l

40 CFR 261,

Hazardous waste Appendix VIII number U122

NTP Carcinogenicity classification Reasonably anticipated 

to be a human 

carcinogen

NTP 2005

Twelfth report on carcinogens; items 

under consideration

Yes NTP 2008

a

Group 1: The agent is carcinogenic to humans.

b

TWA based on effects other than cancer or odor/annoyance using an averaging time of 30 minutes.

c

Sensitization designation refers to the potential for an agent to produces sensitization, as confirmed by human or 

animal data.

d

ERPG-1 is the maximum airborne concentration below which nearly all individuals could be exposed for up to 

1 hour without experiencing other than mild, transient health effects; ERPG-2 is the maximum airborne 

concentration below which nearly all individuals could be exposed for up to 1 hour without experiencing irreversible 

or other serious adverse effects; and ERPG-3 is the maximum airborne concentration below which nearly all 

individuals could be exposed for up to 1 hour without life-threatening health effects (AIHA 1988). e

AEGL-1 is the airborne concentration of a substance above which it is predicted that the general population, 

including susceptible individuals, could experience notable discomfort, irritation, or certain asymptomatic nonsensory 

effects; however, the effects are not disabling and are transient and reversible upon cessation of exposure; AEGL-2 

is the airborne concentration of a substance above which it is predicted that the general population, including 

susceptible individuals, could experience irreversible or other serious, long-lasting adverse health effects or an 

impaired ability to escape; and AEGL-3 is the airborne concentration of a substance above which it is predicted that 

the general population, including susceptible individuals, could experience life-threatening health effects or death 

(EPA 2007a). f

Group 1 pesticide: contains the pesticides that pose a significant risk of adverse acute heatlh effects at low 

concentrations.

g

The EAFUS list of substances contains ingredients added directly to food that FDA has either approved as food 

additives or listed or affirmed as GRAS.

h

A2: Suspected human carcinogen.

i

Group B1: Probable human carcinogen, based on limited evidence in humans, and sufficient evidence in animals.

j

Formaldehyde was recommended to the MTL by Office of Pollution Prevention and Toxics in 1992 and the chemical 

testing program is currently underway under a voluntary testing agreement for emissions testing. k

Designated CERCLA hazardous substance pursuant to Section 311(b)(2) of the Clean Water Act, Section 112 of 

the Clean Air Act, and Section 3001 of the Resource Conservation and Recovery Act.

ACGIH = American Conference of Governmental Industrial Hygienists; AEGL = acute exposure guideline levels; 

AIHA = American Industrial Hygiene Association; CERCLA = Comprehensive Environmental Response, 

Compensation, and Liability Act; CFR = Code of Federal Regulations; DWEL = drinking water equivalent level; 

EAFUS = Everything Added to Food in the United States; EPA = Environmental Protection Agency; 

ERPG = Emergency Response Planning Guidelines; FDA = Food and Drug Administration; FR = Federal Register; 
FORMALDEHYDE 122

Table 7-1. Regulations, Advisories, and Guidelines Applicable to Formaldehyde

Agency Description Information Reference

GRAS = Generally Recognized As Safe; HAP = hazardous air pollutant; IARC = International Agency for Research 

on Cancer; IDLH = immediately dangerous to life or health; IRIS = Integrated Risk Information System; 

NIOSH = National Institute for Occupational Safety and Health; NTP = National Toxicology Program; 

OSHA = Occupational Safety and Health Administration; PEL = permissible exposure limit; REL = recommended 

exposure limit; RfC = inhalation reference concentration; RfD = oral reference dose; SOCMI = Synthetic Organic 

Chemicals Manufacturing Industry; TLV = threshold limit values; TWA = time-weighted average; USC = United 

States Code; VOC = volatile organic compounds; WHO = World Health Organization 
FORMALDEHYDE 123

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