### SCand j 

### work environ health 7 (1981) 95-100



# Formaldehyde exposure in work and the general.:environment

Occurrence and possibilities for prevention

by Raimo Niemela, MSc, Harri Vainio. MD'

NIEMELAR, VAINIOH. Formaldehydeexposure inwork and the general environment: Occurrence andpossibilitiesforprevention. Scandj work environ health7(1981) 95-100. Formaldehyde is extensively used for many different purposes. For this reason, serious

concern has been expressed about the health hazards related to its potent irritating and sensitizing properties. Recently published information about the potential car- cinogenicity of formaldehyde has generated further discussion of the potential health hazards of this compound. This article briefly reviews the health hazards of formaldehyde, the occurrence offormaldehyde in the environment, and general aspects of the prevention of existing hazards.

Key terms: asthmatic reactions, carcinogenicity, environmental exposure, occupational exposure.



### Formaldehyde and its possible health hazards

Irritatingandsensitizingproperties

Forma'ldehyde, the simplest of tJhe aldehydes, is 'chemlcally more reacti'Ve Ithan its higher homologues. 

### It is used extensi'Vely in a wide spectrum of commercial processes.

Exposure to low atmospheric concentrations of formaLdehyde Oa1l!SBS i>rritation, especially ofthe eyes and respiratory tract alt concentraJUODIs abov,e 

### 0.3 cm3/m3 

### (0.38 mg/m3). A clear**dose~respoiU'se** relationship has been observed 

### (17). A conceni'l"atlion

as ,low as 

### 0.5-1 cm3/m3 

### (0.63-1.25 mg/m3)

causes iniltaJtionofthe mucOf\liS membT'anes in some individuals. A!bout 

### 17

### Ofo of the workers exposed 

### to a concentration of 

### 2 ems/ms 

### (2.5 mg/m3) experiences moderate 

### to strong irritarfiion. A formaldehyde con1 Department of Industrial Hygiene and

Toxicology, Institute of Occupational Health, Helsinki, Finland. Reprint requests to: Mr Raimo Niemela, Institute of Occupational Health, Laajaniityntie 1, SF-01620 Vantaa 62, Finland. cellitraltian of 

### 10 cm3/mS 

### (12.5 mg/m3) is tolerated on,ly wi1lh difficulty; expooure 

### to concentrations above this level caus,es

severe difficul:ty in breathing, burning of the'eyes, noseand'trachea, intensel'acrimation, and severe coughing 

### (14).

Direct contact wii1Jh so'lutions, solids, or resins oonta:ilniJng free formaldehyde has been shown to c,ause bo.th inflammatory and allergic dermatitis 

### (14). In Finland

morethan 

### 100casesofoccupationaleczema due to formaldehyde have been reported from 

### 1975 to 

### 1979.

Most of ifue cases of eczema have been allergic reactiJons. In addi'llion a few

oasesofOCcupaitionalasthmahave annually been reported in Finland. Asthmatic symptoms may be due to allergiIC sensitiiIvity 

### to formaldehyde, even at low concellitrations (2). The obstructive symptoms may 

### be of eiJther the acute or the delayed type.



### Carcinogenicity

## offormaldehyde

FormaMehyde is mutagenic in some bacteria, fungi, yeast, and 

### Drosophila (8). furmaldehyde has been Shown 

### to induce



### 0355-3140/81/020095-6single-strand breaks in DNA (deoxyribonuCleic acid) of both prokaryotic a!Ild eucaryotic cells (11, 16). Despite its wide

use and 

### :lm0WlI'l genetic effects, only H'1Jtle infornnation ilS available on its pdbeilibal careinogeruidty. NClJSal carcinomas have been found in 25 % of Sprague-Dawley
rats exposed

### to formaldehyde (14.6 cms/rns; 18.25 mg/mS ), a!Ild hydrochloric acid (10.7

cm3/m3; 13.38 mg/m3) (18). Tumors were suggested 

### to be due to the formation of bis(chloromethyl)ether, a known agent causing nasal cancer (9). Others have suggested, however, that the carcinogenic1ty of bis(chloromethyl)ether may be due
to hydrolysis to forma:ldehyde (19).

Just 'recently, the carcinogenic potential of 'formaldehyde vapor was evaluated in Fischer-344 rats and B6C3Fl miee exposed in inhalaltion chambers to formaldehyde concentraitions of 0, 2, 

### 6 or 15 cm3/mS (0, 2.5, 7.5, or 18.75 mg/mS ) 6 hid, 5 d/week (20, 21). For each species, exposure groups oorusilSted of 120 anima'Is per sex per exposurelevel. Aisix-monlthintervals (at

### 6, 12, 18 

### & 24 months) predetermined numbers of animals of both species were killed and dissected. Dose-related 'histological changes were observed, including rhinitis, epithelial hyperplasia,**~nd** squamous metaplasia. A total of37 and 95 squamous cell carcinomas were detected in rats exposed to a £ormaldehyde concentraltion of 15 Icm3/mS (18.75 mg/mS ) by 18 and 24 montlls, 'respectively. 'I1hree rCllts exposed to 6 cm3/m3 (7.5 mg/mS) hJad developed a squamous cell carcinoma of the 

### nose by 24 months.

Two neoplasms of the nasal turbinates

were identilfied in the mice at 15 cm3/m3 (18.75 mg/m3) exposure levels af,ter 24 months of exposure (WD Kerns, personal**c()lmmun~cation).** No nasal cancers were observed among the con'troil animals.

Whi'1ethe exposure levels used in the experimental c8Jrdnogenidty studies have been higher than those whioh occur at workplaces (table 1) and Whi[e rodents, in contrClJSt to :hurnans, breaJthe through !ffue
nose, thedegree and site ofcarcinogeniciJty
may be modified in humans. As an example, biS'(chloromethyl)ether causes nasal
tumors in rats**~9),** whereas oancers of the lungs aTe found in humans (24). Quantitative hUJIIl·an riJsk assessmerut can be a'ohieved oil'ly after careful and exrtensive epidemiioilogiJC stud1es.

96 

### Formaldehyde in the work environment

Formaldehyde and its derivatives are used in numerous industria:! oper,ations involving ,the 'manu£aiCture, formu:lartion, commercialdistribution, and production of

a variety of products. Formaldehyde is used maittllyin phenoliJc, urea, melamine and acetalresins. These l'e&lns are utilized in llhe production of particle board, plywood, ftulation materials, adhesives, paints, t€xtiles,the coatings ofpapers, 

### etc.

The IMt.1tute of Occupational Health in Finlandhasmeasuredthelevelofairborne formaldehyde iJn occupational and nonoccupa'tionalenv,ironments during the last few yearn. The measurements have 

### been made either as a service based on the ol'ders ofemployers orin conjunction with resea'l'ch projeots. Ai'r samples were collected in midg,et impingers and analyzed by the chromotl'opic add method (7). The results of the measurements of formaldehyde concentratilons are summarized in taMe 

### 1. In Finlland the**1Jh~old** limit value (TLV) ooiJmg fur rthe work environment is 2 cm3/m3 (2.5 mg/m3) (12).

Thetextileindustry usessynthetkresins iJn permanentpress f'abrics, in fireproofing, andindying. The concentrat1ons offormaldehyde used are lower than 1 cms/ms (1.25 mg/m3).

In the tlannin'g and 

### shoe manufaclJu['iJng industry, Formalim® (an aqueous solution offormaldehyde) 

### is used in finishing operations ,to gllue substances toge1Jher. It is sprayed onto the surface 

### to be treated. The ev.apO!I"ation of formaldehyde during this operation 

### 15 so great that the TL

### V for fOI1maldehyde is oiften exceeded.

Synthetd.cresirrl's with £orma'ldehyde as

a componenJtare used in the manufac,turing of 'particle hoard and plywood. The
most commonly used are urea-rormaldehyde, melamine-formaldehyde and phenol- £ormaldehyde resins. These resins aTe sOiluble in water and always conta.i.n a small ,amount Of free formaldehyde. Phenolic resin is nearly the only plywood adhesive used in FmIanid. Particle boaros

are mainlly glued with urea resin, even When**melamine~urea-fol'ma}dehyde** resin is used in the manufacturing of moisture resistarut particle board. Formaldehyde does not evaporate from phenolic resins as readily as from urea and melamine resins.

### For this 

### re-ason the formaldethyde problem is more seriOU!s in the particle board in

### duS/try than tn 

### 1Jhe plywood industry. In 

### the proces!s ofmanufacturing particle board, formaldehyde is relea'sed during ,the following stages: the mixj>ng of glue, the forming stages, the hot pressin,g stage, the cooling stage. The evaporation of 

### fo!rmaldehyde is especiaUy gl'ea:t during the hot pressing and cooling stages. The concentrations of formaldehyde measured range from 0.1 

### to 4.9 

### cm/m3 (1.25 

### to 6.13 

### mg/m3 (13). 

### A great amount of formaldehyde is clhemiJcally 'bound by the curing process. NevertJheless, a small residue remains in'the free or loosely bound starte; during 1Jhe 'course of time, this residue is relea'sed in w,arlfuouses ,and even in dwellings.

The ,release ofresidues offree formaldehyde resulius in 'high concentra,tions during the £1rst year or more. Due to the continuous depoJymerizaHonofformaldehydeurearesin, thereleaseofresidues decreases exponentiaJ]ly to a steady concentr<lJtion whidh is higher than th'e ,concentr,ation of 1Jhe natural !background. Grealter amounts of free formaldehyde in boards result if resins with a ,higher content of free formaldehyde are incorrectly applied or if the resins are insufficiently cured during the pressingstage.

The manufacturing of wooden furniture I1equiresa wide rang,e of adhesives, lacquers, paints, and hardeners cOJltaining formaldehyde as a component. Formaldehydeis r,eleasedduringthemixing, spreading, hOlt pressing and drying operations of glue application. During painting, the highest fOI1maldehyde exposure occurs during \jjhe application and drying process. The formaldehyde concentrations measured have been quite high; 18

### Ofo of the measuremenits obtained exceeded the Finnish TLV of2

### em3

### /m3 (2.5 

### mg/m3). 

### This valJue was exceeded in an adhesive plant during 'the manufacture of urea resins.

At present, many welding metals are painted or treated with corrosion preventiNes cOJlltaining synthetic resins. The product,s of ,thermal decamposirtion may eontain 'formaldehyde. Painting is also a typiJcal work operation in machine shops. Forma;ldehyde exposure may occur if**~he** 

### pai'!llts used contain forma1dehyde. The formal1 

### deihyc1e concentrations measured have usually been below 2 

### em3

### /m:l (2.5 

### mg/m3).



### In the manufacturing of elec1'rical machinery 'and apparatus, soldering and lacTable 1. 

### Airborne formaldehyde concentration in occupational and nonoccupational environments. Air samples were taken during 10 

### min - 2 h and analyzed with the chromotropic acid method.

Items

Textile plants

Shoe factories Particle board plants Plywood plants Wooden furniture manufacturing plants Adhesive plants Foundries

Welding and machine shops
Workshops manufacturing electrical machinery

Soldering Lacquerng, treatment of plastic Construction sites Hospitals, policlinics Offices, schools
Dwellings Formaldehyde concentration (cm'/m')" Number of Source

items',l Arithmetic Number of Range measure- mean ments

2 (1977-1979) 0.2**0.1~.5** 16 Finishing and dyeing substances 1 (1977) 1.9 0.9-2.7 4 Formalin spraying 3 (1977-1979) 1.15 0.1--4.9 220 Urea and melamine resins 6 (1977-1979) 0.35 0.1-1,2 91 Phenolic and urea resins 19 (1977-1979) 1.35 0.1-5.4 134 Adhesives, lacquers, paints

1 (1977) 1.75 0.8-3.5 17 Urea-formaldehyde resin 10 (1972-1975) 2.7 43 Furan resin (38% 

### >TLV) 3 (1977-1979) 0.6 0.05-2.0 8 3 (1977-1980) 0.5 0.05-1.2 9 Plastic tape, paints, corrosion preventive 10 (1977-1979) below 0.1 47 Solder 0.35 0.2-0.5 8 Lacquer, melamineformaldehyde plastic

7 (1974-1975) 2.8 0.5-70 10 Lacquer 7 (1977-1979) 0.7 0.05-3.5 25 Formaldehyde disinfectant 4 (1977-1980) 0.24**0.05~.77** 12 Insulation foam, adhesive,
(1976--1980) lacquer 65 0.29**0.01~.93** 186 Particle board, insulation foam, glue of wall panel

a Year(s) of measurement in parentheses.

" 1 cm'/m' 

### = 1.25 mg/m'.



### 97

### quel"mg arecommonworkoperations. This industry uses a great variety of plastic produots. Many solders contain colophony resinswhosepyrolysisduring 1lhesolderilng operation produces formaLdehyde (3). The formaldehyde concentrations measured have been very low, below 0.1 em3

### /m3 

### (0.13 mg/m3). 

### The formaldehyde**concen~** 

### tra'tJions measured were below 0.5 

### om3

### /m3 

### (0.63 mg/m3) 

### during the preSJSing of melamine-fo:vma1dehyde plastics and the lacquering of

### transformers.

The cold-setting furan resins are used in foundries as binding agents for sand, mainly in the making of oo.res. Furan binder.s contain either urea-formaldehyde

or phenol-formaldehyde resins. As a voLantle co,mponent in furan resin, formaldehyde is released into the ,air of the workroom when the sand is mixed and when thecor,e boxes are filLed. According to a study of Finn1sh foundries in 1972-1975, 

### 38 

### Ofo of :the measurements obtained exceeded the TLV (23). 

### Later measuremen.ts, im 1977-1979, 

### basedonoJ:1ders from f<>U'llddes showed somewhat lower cc>ncentrations offormaldehyde.

Inthe construction industry, the hig'hreslt formaldehy;de exposure was found during the :lacquering of parqu,et floors (1). In most cases, carbamidelacquer oftwo components was used for 

### this purpose. Carbamide lacquer 'always contains some free fol'maldehyde, which evaporaJtes dUTing the application and drying of the lacquer. The aVe1'age concentrati·on of formaldehyde was at the level of 2 

### em3

### /m3 

### (2.5 

### mg/m3); 

### 40 

### Ofo of the measurements exceeded the present Finnish TLV. Momentary concentrations we,refound tobemany times greater than rthe average figure.

In hospitaLs, formaldehyde is used to preserve tissue specimens and as an agent ofchemical sterilldzation. Momerutary forma1dehyde conceTIJtl'a'tions stemming from autoclaves and disinfection have exceeded the VJaliJd TLV, bUit the time-weighred average 'has remained below 1 ems/ms (1.25 

### mg/m3).



### Even th<:mgh particle boaI1d is 

### a COiIIl

### mOIl C·OIIlstruOtion malteri'al in 

### offiices and 

### schools, the f.o:vmaldehy;de problems which

we have encounter·ed have occur.red only inIthepr·eseIlJee ofothers<>Urces orr. formaldehyde. Urea-fo:vmaldehyde foam, which irs used for thermal insuJation, has caused problems along with carpet adhesive or



### 98 parquet lacquer. The fact that particle boardhasoawediless complaints in offices andschools than in dwellings is obviously due ,to 

### better veIliti1a1llon. Ul'ea-formaidehydelinsularlion foam maycause**iong~term** 

### releas€s of 

### fomnaldehyde. Formaldehyde evolves fromearpetadhesives andlacquers on!ly during short periods ofappJicaition and drying. Evaporation for 

### a few weeks, howev·er, is possi:ble ifth·e composition of lacquer and 

### hardener is incorrect. The measured concentrationshaverangedfrom 0.05 

### to 0.77 

### ·cm3

### /m3 

### (0.06 

### to 0.96 

### mg/m3).



### Formaldehyde in nonoccupational environments

Formaldehyde commonly occurs in nonoccupa1:ional environments. It 

### i,s fo:vmed during 1Jhe:thermal decomposition. ofmany organic substances. The concenwation of aildcl1yde intthe eX!haustfumes of 

### combustion motors is usuaHy 10-30 

### em3

### /m3 

### (12.5-37.5 

### mg/m3).**C~garette** 

### smoke contains even more fOI1IIlJaldehyde than the preViaiEng TLV '(22). 

### Some drugs used in thetreatmentofurinaryinfections (methenamine mantdelJate and methenamine hippurate) are metabolized in a way that fOI'maldehyde is released in the urinary
traot (10).

In dwellings, formaLdehyde evaporates from 'construotionmaterials and :turniJtu.re. The InsUtute of Occupational Health in 

### Finland has measul'ed the formaldehyde concentration in 65 

### dwellings during the last 4 a. PaI1tic1e boavd was the main soU'oce of formaldehyde in 61 

### dwellings, urea-formaLdehyde foam iIn 

### 3, and the adhesive of a waH panel in 1. 

### The highest measured**concentrat~on** 

### was 0.93 

### em3

### /m3 

### (1.16 

### mg/m3). 

### In F.inland, no indoor air standards for nonoccupational enIYhx>I1-
ments have heen set. An upper limit for f.ormaldehyde concentration

- 0.12 em3

### /m3 

### (0.15 mg/m3) - 

### has lbeen suggeSited for the indoorhome environmentin Denmark (6). According 10 

### Da'IlJish investigatioll1S (4, 5), the conceIlltmtion of formaldehyde in 

### dweNings depends on,the sources offormaldehyde, :the age ofthe buiJdiIng, verutilation, air !temperature, and ak humidity condiJtions.

ThestandaroproposalforminimumventilaHon in 

### dwellings put forwavd by the Nordic Commi.1ltee for Buillding Codes is

### 0.5 air change/h 

### (15). In some modern dwellings today, however, it is as low

as 

### 0.1 change/h. These low ventilation
rates cause an increase in indoor humidity; in periods when the sun shines through the windows of well-insulated dwellings, the hot-humid indoor environmern and the low rate of ven:ti'lation
may cause high indoor concentrations of formaldehyde. 11herefore, the change in building .teohnology caused by inoreases in the cost of energy may aggravate the hazards of formaldehyde.



### Control and elimination of formaldehyde hazards
Substituting a less toxic compound for toxk malberial is :jjhe classic propo,sal for reducing risk,s to workers' heaG.rtfu. Formaldehyde is an important and inexpensive chemicalit-hat iJsusedinmany ways, and it is thereforenot'an easy taskto find a substitute. However, it has been possvble 

### to reduce the airborne forma,Mehyde concentrations, eg, in the plywood and particle board industries, by rearrang,ing ventila

### hon, Iby 'lliring new types of glues, and by other simi'lar methods (13).

Any process including the 'hand-ling of formaldehyde should the isolated 

### as completely aJS possible. If total isolation is impossi!ble, then art; least the strongest

sources of emission should be enclosed. Spray booths or rooms, as well as drying
areas, should be equipped with exhaust systems. In ca:ses oflesser sources offormaldehyde, it is possijble to remove vapors with local exhaust ventilation. If formaldehyde evaporates from large sunEaces, general ventilati'On should be effective enough. In some ca\ses formaldehyde exposure is of short durati'On; i!t is then possible to reduce exposure by 

### ,the use of
proper respirators.

The most sertous problems in dwe'llings arise when residents move into 

### a newly constructed 'house wirth unfinished or pOOl" quality 'partide boards. For the reduction of formaldehyde hazards in dwellings, the
amount of free formaldehyde in boards
must be kept 

### as low as possible. Effective quality control of b(}ards is therefore necessary. The rate of air dhange shou1d be sUlffideIlJt. Treatment with a formalde**hyde~bsor:biJng** paint can also reduce evaporation (6). 

### References

1. Ahonen K, Engstrom B, Lehtinen PU. Rakennustyokartoitus. Institute of Occupational Health, Helsinki 1977. (Tyoolosuhteet 7). 2. Alanko K, Keskinen H, Saarinen L. Ammattiastma [Occupational asthma]. Duodecim 93 (1977) 306-318. 3. American Conference of Governmental Industrial Hygienists. Documentation of the threshold limit values for substances in workroom air. Cincinnati, OH 1976. 4. Andersen I, Lundqvist GR, Molhave L. Formaldehyde indeluft i danske boliger. Ugeskr laeg 136 (1974) 2133-2139. 5. Andersen I, Lundqvist GR, Molhave L. Indoor air pollution due to chipboard used

as a construction material. Atmos environ 9 (1975) 1121-1127. 6. Andersen I, Lundqvist GR, Molhave L. Formaldehyde i boligluft. Ugeskr laeg 141 (1979) 966-971. 7. Finnish League for Standardization. Determination of formaldehyde in workplace air with chromotropic acid method. Helsinki 1978. (SFS 3862). 8. Fishbein L. Pontential industrial carcinogens and mutagens. Elsevier, Amsterdam-axford-New York 1979, pp 142-147. 9. Kuschner M, Laskin S, Drew RT, Capiello V, Nelson N. The inhalation carcinogenicity of alpha halo ethers: III. Lifetime and limited period inhalation studies with bis(chloromethyl)ether at 0.1 ppm. Arch environ health 30 (1975) 73-77. 10. Laaketietokeskus. Pharmaca fennica 1980. Oy Lansi-Suomi, Rauma 1979. 11. Magna-Schwencke N, Ekert B, Moustacchi E. Biochemical analysis ofdamage induced in yeast by formaldehyde: I. Induction of single-strand breaks in DNA and their repair. Mutation res 50 (1978) 181-193. 12. Ministry of Social Affairs and Health. Tyopaikan ilman epapuhtauksien enimmaispitoisuudet. Institute of Occupational Health, Helsinki 1972. (Sosiaali-jaterveysministerion vahvistamat teknilliset turvallisuusohjeetno 11). 13. Niemela R, Riipinen H, Aatola S, Kahko-

nen E, Makela P, Vaha-Soyrinki A. Ilmanvaihto lastulevy- ja vaneritehtaissa. Institute of Occupational Health, Helsinki 1980. (Tyoterveyslaitoksen tutkimuksia 164). 14. Nordiska expertgruppen fOr gransvardedokumentation. 1. Formaldehyd. Arbetarskyddsverket, Stockholm 1978. (Arbete oeh balsa 1978: 21). 15. Nordiska Kommitten for byggnadsbestammelser. Riktlinjer for byggnadsbestammelser rorande inomhusklimat. Forslag 23 April 1980. 16. Poverenny AH, Siomin YA, Saenko AS, Sinziniz BI. Possible mechanisms of lethal and mutagenic action of formaldehyde. Mutat res 27 (1975) 123-126. 17. Sehunck EA, Stephens ER, Middelton JT. Eye irritation response at low concentrations of irritants. Arch environ health 13 (1966) 570-575.



### 9918. Sellakumar AR, Albert RE, Rusch GM, Katz GW, Nelson N, Kuschner M. Inhalation carcinogenicity of formaldehyde and hydrogen chloride in rats. Proc am assoc
cancer res 21 (1980) 108. 19. Shooter IV. Assays for phosphotriester formation in the reaction of bacteriophage R17 with a group of alkylating agents. Chemio-biol interactions 11 (1975) 575-588. 20. Swenberg J, Kerns W, Pavkov K, Mitchell R, Gralla EJ. Carcinogenicity of formaldehyde vapor: Interim findings in a longterm bioassay of rats and mice. In: Abstracts ofthe second international congress of toxicology, Brussels, July 6-11, 1980. Toxicol lett (1980) 66.

Received for publication: 3 December 1980



### 100 21. Swenberg JA, Kerns WD, Mitchell RI, Gralla EJ, Pavkov KL. Induction of squamous cell carcinomas of the rat nasal cavity by inhalation exposure to formaldehyde vapor. Cancer res 40 (1980) 3398- 3402. 22. Vainio H, Sorsa M, Hemminki K. Tupakoinnin mutaatioriskit. [Mutational risks of smoking]. Duodecim 96 (1980) 620-627. 23. Virtamo M, Tossavainen A. Gases formed from furan binding agents. Scand j work environ health 2 (1976): suppl 1, 50-53. 24. Weiss W, Moser RI, Auerbach O. Lung

cancer in chloromethyl ether workers. Am

rev resp dis 120 (1979) 1031-1037.