UNTTEDSTATESE~ONMENTALPROTECTIONAGENCY 

WASHINGTON,D.C. 20460 RECEIVEl.:. 

February 5, 1998 

OFFI<;:EOF 

PREVENTION, PESTICIDES AI~<'D 

TOXICSlJBSTANCES 

SUBJECT: Review of Methyl Parathion Incident Reports _ 

DP Barcode D242333, Chemical #053501, Reregistration 

Case#0153 

FROM: Jerome Blondell, Ph.D., Health Statistician 

Chemistry and Exposure Branch 2 r.u ,_0 e 

Health Effects Division (7509C) ~ ~ 

THRU: 

TO: 

BACKGROUND 

Monica F. Spann, MPH, Environmental Health Scientist 

chemistry and EXJ?o~u:e Branch 2 1\\-:-r~. ~ _1_ ::r:.._ -----

Health Effects D~v~s~on (7509C) · · f 

Susan v. Hummel, Senior Scientist . l, , /1 .A _,L -1___; _ ~~""'~ Chemistry and Exposure Branch 2 -~·-·-

Health Effects Division (7509C) 

Jonathan Becker, EnvironmenLal Health Specialist 

Reregif?tration B'ranch 2· 

Health Effects Division (7509C) 

The following data bases have been consulted for the poisoning 

incident data on the active ingredient Methyl Parathion (PC Code: 

053501) : 

1) OPP Incident Data System {IDS) - reports of incidents from 

various sources, including registrants, other federal and state 

health and environmental agencies and individual . consumers, 

submitted to OPP since 1992. Reports submitted to the Incident -7 

Data System represent_~I1ecd<?t~l re2_9rts or allegations only, unless / 

otherwise stated. Typically no conclusions . can be -drawn . 

implicating fhe pesticide as a cause of any ·of. the reported health 

effects. Nevertheless, sometimes with enough cases and/or enough 

documentation risk mitigation measures may be suggested. 

2) Poison Control Centers - as the result of Data~Call-Ins issued 

in 1993, OPP received Poison Control Center data covering the years 

1985 through 1992 for 28 organophosphate and carbamate chemicals. 

Most of the national Poison Control Centers (PCCs) participate in 

a national data collection system, the Toxic Exposure Surveillance 

System which obtains data from about 70 centers at hospitals and 
2 

a national data collection system, the Toxic Exposure Surveillance 

System which obtains data from about 70 centers at hospitals and 

universities. PCCs provide telephone consultation for individuals 

and health care providers on suspected poisonings, involving drugs, 

household products, pesticides, etc. 

3) California Department of Food and Agriculture (replaced by the 

Departmen,t of Pesticide Regulation in 1991) California has 

collected uniform data on suspected pesticide poisonings since 

1982. Physicians are required, by statute, to report to their 

local health officer all occurrences of illness suspected of being 

related to exposure to pesticides. The majority of the incidents 

involve workers. Information on exposure (worker activity), type 

of illness (systemic, eye, skin, eye/skin and respiratory) 1 

likelihood of a causal relationship, and number of days off work 

and in the hospital are provided. 

4) . National Pesticide Telecommunications Network {NPTN) - NPTN is 

a toll..:free information service supported by OPP. A ranking of the 

top 200 active ingredients for which telephone calls were received 

during calendar years 1984-1991, inclusive has been prepared. The 

total number of calls was tabulated for the categories human 

incidents, animal incidents, calls for information, and others. 

METHYL PARATHION REVIEW 

I: Incident Data System 

Please note that the following ca~es from the IDS do not have 

documentation confirming exposure or health effects- i.n1.less 

otherwise noted. 

Incident# 000578 001 

A pesticide incident occurred in 1993, when nineteen workers 

were exposed to methyl parathion and two other pesticides when 

entering an apple.orchard two or three days after application to 

thin the fruit. The other two pesticides, calcium chloride and 

Systhane/Mycloburanil, are not cholinesterase inhibitors. They all 

reported experiencing some combination of headaches, diarrhea, 

nausea, and one worker had a bloody nose. In another incident in 

the same field, sixteen workers {perhaps of the original 19) reentered the area 49 hours after methyl parathion (Penncap M) was 

sprayed·and a few complained of illness. The next day all sixteen 

workers were complaining of illness (headache, nausea, diarrhea) 

and left the field. No one sought medical treatment, so blood 

cholinesterase was not measured. No further information on the 

disposition of .the case was reported. 
3 

Incident# 000894 004 

~pesticide incident occurred in 1992, when several inspectors 

found more than 200 gallons of methyl parathion in a basin and 

experienced burning throats, sore eyes, and fatigue. No further 

information on the disposition of the case was reported. 

Incident# 001280 004 

A pesticide incident occurred in 1994, when a veterinarian 

smelled a container with methyl parathion and became ill. No 

further information on the disposition of the case was reported. 

Incident# 001769 001 

A pesticide incident occurred. in 1994, when a woman was 

sprayed with methyl parathion by an aerial applicator and 

experienced blurred vision, disorientation, weakening in the legs, 

and memory lapses. She reported that the symptoms persisted for 

eleven months. 

Incident# 002225 001 

A pesticide incident occurreQ in 1995, when an individual was 

packaging containers of methyl parathion and experienced nausea. 

No further information on the disposition of the case was reported. 

Incident# 002431 001 

A pesticide incident occurred in·1995, when a three year old 

boy was exposed to methyl parathion after a pig rooted out a hole 

in the ground which had previously been an old farm surrounded by 

a fence. The boy played in this same area and experienced 

vomiting. No further information on the disposition of the case 

was reported .. 

Incident# 002479 001 . A pesticide incident occurred in 1995, when a man was sprayed 

with methyl.parathion that was applied aerially and two weeks later 

experienced convulsions anQ seizures. Symptoms during the two week 

period were not reported. No further information on the 

disposition of the case was reported. 

'Incident# 002922 001 

A pesticide incident occurred in 1995, when a man was 

accidentally sprayed with methyl parathion that was applied 

aerially to a cotton field. Specific symptoms were not mentioned. 

No further information on the disposition of the case was reported. 

Incident# 003599 001 

The Minnesota Department of Agriculture surveyed state 

enforcement agencies t'o determine what pesticides were involved in 

spray drift. Among the thirty-two states responding to· the survey, 

there was a .total of 2, 681 cases of drift complaints related to 

specific pesticides. Methyl parathion was responsible for 7 

complaints or less than one percent of the total. 
4 

Incident# 003976 001 

A pesticide incident occurred in 1996, when a crop advisor, 

who was scouting corn fields 48 hours after spraying with methyl 

parathion. He experienced nausea, blurred vision, and excessive 

salivation. He did not see a doctor but remained in bed several 

days. No further information on the disposition of the case was 

reported. 

Incident# 004420 001 

A pesticide incident occurred in 1996, when a woman and her 

son were sitting on their back porch and were sprayed with methyl 

parathion. The woman experienced nausea, chest tightness, soreness 

over her entire body, and body tremors. The son experienced 

diarrhea, skin irritation, and headaches. No further iriformation 

on the disposition of the case was reported. 

Incident# 004439 142 

A pesticide incident occurred in 1996, when an individual was 

drenched with methyl parathion and_gied. Despite repeated followup ..!!2-- infQJ;:mat;i.on could be obtained ~.9- verify this incident. 

II. Poison Control Center Data 

Methyl Parathion was one of 28 chemicals for which Poison Control 

Center (PCC) data were requ~sted. The following text and statistics 

are taken from an analysis-of these data; see December 5, 1994 memo 

from Jerome Blondell to Joshua First. 

The 28 chemicals were ranked using three types of measures: (A) 

number and percent occupational and non-occupational adult 

exposures reported to PCCs requiring treatment, hospitalization, 

displaying symptoms or serious life-threatening effects; (B) 

California data for handlers and field workers comparing number of 

agricultural poisonings to reported applications; and {C) ratios of 

poisonings and hospitalization for PCC cases. to estimated pounds 

reported in agriculture for pesticides used primarily ln 

agriculture. 

A. Occupational and Non-occupational Exposure 

There were ~ total of 274 methyl parathion cases in the PCC data 

base. Of these, 10~ cases were occupational exposure; 91 (89%) 

involved exposure to methyl parathion alone and 11 {11%) involved 

exposure to multiple chemicals, including methyl parathion .. There 

were a total of 146 adult non-occupational exposures; 113 {77%) 

involved this chemical alone and 33 (23%) were attributed to 

multiple chemicals. 1 

1 Workers who were indirectly exposed (not handlers) were classified as nonoccupational cases. 
5 

In this analysis, four measures of hazard were developed based on 

the Poison Control Center data, as listed below. 

1. Percent of all accidental cases that were seen in or referred to 

a health care facility (HCF) . 

2. Percent of these cases (seen in or referred to HCF) that were 

admitted for medical care. 

3. Percent of cases reporting symptoms based on just those cases 

where the medical outcome could be determined. 

4. Percent of those cases that had a major medical outcome which 

could be defined as life-threatening or resulting in permanent 

disability. 

Exposure to methyl parathion alone or in combination with other 

chemicals was evaluated for each of these categories, giving a 

total of 8 measures. A ranking of the 28 chemicals was done based 

on these measures with the lowest number being the most frequently 

implicated ih adverse effects. Table 1 presents the analyses for 

occupational and non-occupational exposures. 
6 

Table 1: Measures of Risk From Occupational and Non-occupational 

Exposure to Methyl Parathion Using Poison Control Center Data from 

1985-1992a 

Occupational Exposure Non-occupational Exposure 

Percent Seen in HCF 

Single chemical 81.3 5 (68.2) 58.4* (44. 0) 

exposure 

Multiple chemical 82.45 (69.8) 63. 7*6 (46 .1) 

exposure 

Percent Hospitalized 

Single chemical 9.5* (12.2) 9.1* (9. 9) 

exposure 

Multiple chemical 13.1* (14.3) 14.0* {12. 6) 

exposure 

Percent with Symptoms 

Single chemical 72.7* (85.8) 80.0* (74. 0) 

exposure 

Multiple chemical 75.0* {85.8) 81. 3*7 {75. 2) 

exposure 

Percent with Life-threatening Symptoms 

Single chemical 0.0 (0. 0)- 0.0* (0. 0) 

exposure - Multiple chemical 1.2 (0.5) 0.0* (0.05) 

exposure 

a Extracted from Tables 2, 3, 5 and 6 ~n December 5, 1994 memo from Jerome Blondell 

to Joshua First; number in parentheses is median score for that category 

* Top 25% of chemicals are ranked with a superscript of 1 to 7 

Including exposure to multiple chemicals, methyl parathion had 

the fifth highest percent of occupational cases .seen in a health 

care facility (Table 1) . On other measures of hazard (percent 

hospitalized, percent with symptoms or life-threatening symptoms) , 

methyl parathion had percents similar to the median 'for other 

cholinesterase-inhibitors, sometimes higher and sometimes lower. _j 

B. Ratios of poisoning - California Data 

The in<;:idence of· systemic poisoning cases in agricultural 

workers reported to the California was comp~red to the number of 

applications of methyl parathion. Those calculations, along with 

the median score for a total of 29 pesticides, are presented in the 

Table 2 below. 
7 

Table 2: Systemic Poisonings/1,000 Applications in Selected 

Agricultural Workers Exposed to Methyl Parathion in California, 

1982 -1989a 

Number Poisonings/1,000 Appl. (N) Poisonings/1,000 Appl. (N) Pesticide of Primary Pesticide Only Multiple Pesticide 

Appl. Exposure 

Handlers Field Total Handlers Field Total 

Workers Workers 

Methyl 4S,S97 .04 (2) .00 (0) .04 .09 (4) .04 (2) .13 

Parathion (2) (6) 

Median .21 .20 .41 .44 .so 1. 02 

a Extracted from Table AS ~n December S, 1994 memo from Jerome Blondell to Joshua 

First; number in parentheses is the observed number of poisoned cases. 

Methyl Parathion had much lower ratios of handler poisonings 

and field worker poisonings per 1,000 applications in California; 

regardless of whether exposures to mixtures were included or not. 

For total poisoning per 1,000 applications where methyl parathion 

was deemed the primary cause of the incident, only two other 

pesticides (bacillus thuringiensis and permethrin) had lower 

ratios. This is an unusually good record for an organophosphate 

insecticide, suggesting that worker practices in place in 

California from 1982 through 1989 were both safe and effective. 

C. Ratios of Poisoning -·u.s. Poison Control Data 

Active registrations of methyl parathion are for agricultural 

use exclusively. Ratios of the number of occupational Poison 

Control Center exposures to the reported pounds of the chemical 

used2 were calculated. The results for methyl parathion and the 

median for the 15. agricultural. chemicals included in the analysis 

are presented in the Table 3 below. 

Table 3: Ratios of Methyl Parathion Poisonings (PCC Data, 1985-

1992) to Reported Usea 

Exposure Poisonings .Health Care Hospital Admitted 

Pesticide Per Use Per Use Referral Per Use Cases Per Use 

Methyl # .013* .008* .010* .001* 

Parathion -· 

Median .033 .013 .027 .004 

a Extracted from Table 9 ~n the December 5, 1994 memo from Jerome Blondell to 

Joshua First 

* Top 33% of chemicals are ranked with a superscript of 1 to 5 

2 Gianessi, L.P., Puffer, C.A. Insecticide Use in U.S. Crop Production. 

Resources for the Future, Washington, D.C., 1992·. 

-, 
8 

Among pesticides used exclusively in agriculture, methyl 

parathion had the third lowest ratio of exposures, poisonings, and 

treatment to estirn~ted pounds active ingredient reported in use 

(Table 3}. Methyl parathion had second lowest ratio of 

hospitalized cases per estimated pounds used. Based on these 

measures, methyl parathion appears to be much less likely to be 

involved in potential poisonings than other organophosphate and 

carbamate insecticides. 

D. Exposure in Children 

A separate analysis of the number of exposures in children 

five years of age and under from 1985-1992 was conducted. For 

methyl parathion, there were 26 incidents; 23 involved exposure to 

methyl parathion -alone and 3 involved other pesticides as well. 

Because of the relatively small number of cases, no statistical 

comparisons were--ma-de with other organophosphates and carbarnates. 

E; Environmental and Misuse accidents 

The American Association of Poison Control Centers (AAPCC) 

provided data on over 100,000 exposures from 1985 through 1992 for 

28 pesticides. A search was performed on this data for those 

pesticides with no significant horne use, but large agricultural use 

('n = 15) . Only exposures where the r·esidence was the site of the 

exposure and the pesticide prodUct was the sole product involved in 

the exposure were included in the analysis. The table below shows 

the results where reason was environmental or misuse. AAPCC 

defines these terms as follows: 

Environmental: any passive exposure that results from man-made 

contamination of the environment, e.g. exposures to contaminated 

water resulting from improper disposal of chemicals, passive 

inhalation of toxic fumes or gases as a result of discharge at a 

plant -or a "HazMat" incident .. 

Misuse: An accidental exposure which results from the improper or 

incorrect use of a substance where therapeutic or beneficial 

results were intended. 

The ocher commonly used "reason" categories are general, 

occupational, unknown, and intentional (includes suicide and 

abuse) . General is defined as: all unintended poisonings or 

exposures that_ are not specifically defined by other categories, 

including most accidental exposures to children, bites, stings, 

plant exposures and unintentional food poisoning. 

Obviously there is considerable 'gray area' between these 

categories and many scenarios can be imagined where different 

poison specialists would assign different categories. For example, 

spray drift could be counted as environmental or misuse and 

/ 
9 

probably accounts for the majority of cases recorded. The purpose 

of this analysis was to find out if it might be used to identify 

agricultural pesticides illegally applied in the home environment. 

The other key problem with AAPCC data, particularly severe in 

this case, is the lack of representation. in certain states. 

Thirteen states had little or no coverage by AAPCC during the time 

period of interest. They were Nevada, Oklahoma, Texas, Arkansas, 

Mississippi, Illinois, Iowa, North Carolina, South Carolina, 

Delaware, Connecticut, Vermont and Maine. In particular, the 

absence of data from Mississippi, the Carolina, Arkansas, Texas and i 

Oklahoma is likely to miss a substantial portion of misuse problems 

due to methyl parathion. 

Table 4. AAPCC exposures for agricultural pesticides reported in 

residences due to environmental exposure ·or misuse, 1985-1992 

(ratio = environmental + misuse/ pounds active ingredient) . 

Pesticide Environ- Env. + Pounds ai E+M/P 

mental Misuse Misuse 1989-91 ratio 

aldicarb 30 6 36 5000 7.2 

azinphosmethyl 16 3 19 3000 6.3 

carbofuran 12 19 31 1500 20.7 

dicrotophos 2 2 4 

ethoprop . 2 0 2 750 2.7 

- fenamiphos 0 0 0 800 0.0 

fonophos i2 1 13 

methamidophos 15 0 15 1230 12.2 

methidathion 1 1 2 520 3.8 .. 

methyl 29 5 34 8180 4.2 

parathion 

mevinphos 3 0 3 420 7.1. . phorate 3 5 8 2902 2.8 

profenofos -· 0 0 0 900 0.0 

sulfotepp 7 0 7 

terbufos . 4 4 8 

The conclusion from examining Table 4 is that the categories. 

for environment and misuse can not be used to identify agricultural 

pesticides, like methyl parathion, that may be applied indoors. 
10 

III. California Data - 1982 through 1995· 

Detailed descriptions of 18 cases submitted to the California 

Pesticide Illness Surveillance Program (1982-1995) were reviewed. 

In 7 of these cases, methyl parathion was used alone and was judged 

to be responsible for the health effects. Only cases with a 

definite, probable or possible relationship were reviewed. Methyl 

parathion ranked 90th as a cause of systemic poisoning in 

California (1982-1994) . Tabl~ 5 presents the types of illnesses 

reported by year. Table 6 gives the total number of workers that 

took time off work as a result of their illness and how many were 

hospitalized and for how long. 

Table 5. Cases Due to Methyl Parathion Exposure in California 

Reported by Type of Illness and Year, 1982-1995 

Illness Type 

Year Systemica Eye Skin Respiratory Total 

1982 1 1 - - 2 

1983 1 - - - 1 

- 1984 - - - - - . -

1985 - - - - -

1986 - - - - -

1987 1 - - - 1 

1988 - - - - -

1989 - - - - -

1990 2 .. - - - 2 

1991 - - - .- -

1992 1 - - - 1 

1993 ~ 

- - - - -

. 1994 .. - - - - -

1995 - - - - -

Total 6 1 - - 7 

a Category includes cases where skin, eye, or respiratory effects 

were also reported 
11 

A total of 6 persons had systemic illnesses or 86% of 7 cases. 

Five of these workers took between two and five days off work as a 

result of their illness as shown in Table 6 below. One worker was 

hospitalized for four days after spraying the insecticide inside a 

greenhouse. A variety of worker activities were associated with 

exposure to methyl parathion as illustrated in .Table 7 below. 

Table 6. Number of Persons Disabled (taking time off work) or 

Hospitalized for Indicated Number of Days After Methyl Parathion 

Exposure in California, 1986-1995. 

Number of Persons Number of Persons 

Disabled Hospitalized 

One day - -

Two days 2 -

3-5 days 3 1 

6-10 days - -

more than 10 days - -

Unknown - - . - . 

Table 7. Illnesses by Activity Categories for Methyl Parathion 

Exposure in California, 1986-1995 

Illness Category 

Activity Systemicb Eye Skin Respirat'ory Tc>tal Cat ego~ 

Applicator 2 1 - - 3 

Driftexp 2 - - - 2 -

Other 2 - - - 2 . Total 6 - - - 7 

a Dr1.fte xp = e xp osure·· to p est1.c1.de t :tat has dr1.fted from 1.ntendec 

targets; Other= other occupational exposure 

b Category includes cases where skin, eye, or respiratory effects 

were also reported 

According to the above activity categories,·applicators (two 

by hand and one by spray rig) were associated with three illnesses. 

The most serious case experienced muscle spasms, vomiting, 

\~~ \ ' 
-~ 

12 

diarrhea, and abdominal pain and was hospitalized for four days. 

One of the cases classified as other was a person downwind from a 

spill, similar to the two drift exposure cases. These cases 

reported symptoms of headaches, difficulty breathing, nausea, 

diarrhea, vomiting, weakness, sweating, and itching around the 

mouth. 

IV. NPTN 

On the list of the top 200 chemicals for which NPTN 

received calls from 1984-1991 inclusively, methyl parathion was not 

·reported to be involved in human incidents. 

V. Literature Review 

Two incidents involving deaths have been reported in 

Mississippi from misuse of methyl parathion inside homes. The 

first incident reported in 1977 involved seven of 13 members in one 

family who developed weakness, abdominal pain, nausea, vomiting, 

difficulty seeing, excessive sweating and salivation. The father 

of the rural farm family had taken some concentrated methyl 

parathion from a discarded drum and placed it in a nebulizer and 

then sprayed his home for cockroaches. A 26. year old, died as- a --~ 

result of organophosphate poisoning confirmed by cholinesterase // 

testing. 

In the second incident, the male live-in companion sprayed the 

house to control spiders. He had obtained a nearly empty .container 

of methyl parathion from the farm he worked on and added water to 

it. He used a hand sprayer. to spray the solution on the inside 

upper walls of three of the four rooms (excluding the kitchen) in 

the house. The concentration in the hand sprayer was found to be 

three times that used for outdoor agricultural application. It· was 

suspected that methyl ·parathion got into the food and drinking 

water, as well as .being present in the air and on surfaces. All 

seven children in·the home became ill and were hospitalized with 

confirmed cholinesterase inhibition. Two of the five children, a 

four year old and an eleven year ~ld, died. 

Numerous cases of exposure inside homes have been documented 

in Ohio, Mi~higan, Mississippi, Louisiana and elsewhere. These 

exposures have occurre.d due to illegal application by PCOs going 

door to door. Tci"tal number of people exposed from these 

applications number in the thousands and over 1,000 people have had 

to be relocated while their home were decontaminated. The 

estimated cost of clean up exceeds $70 million. There_have been 

reports of symptomatic human cases and pets that have been 

adversely affected or died. However, these cases have not been 

confirmed by cholinesterase testing and the reported cases have not 

been published in the scientific literature. 
012848 

13 

VI. Conclusions 

Exposure to methyl parathion can lead to systemic illness. In outdoor agricultural situations, the primary activities associated 

with poisoning are application and spray drift. Compared to other organophosphate and carbamate insecticides, methyl parathion is 

associated with less poisoning when adjusted for amount of use. To 

some extent the similarity between the methyl parathion and the far 

more toxic ethyl parathion (in terms of poisonings and deaths even 

after adjusting for use), may have resulted in workers handling any product with the 'parathion' name with greater care. 

Interior home use of methyl parathion has resulted in deaths 

in two separate incidents in Mississippi. Food or water 

contamination and an unusually high concentration used in the application probably contributed to these deaths which occurred in 

the 1970s and early 1980s. The more recent cases exposed primarily 

in Ohio, Mississippi, and Louisiana have not been well documented 

or confirmed with cholinesterase testing. 

VII. Recommendations 

Numerous actions have already been taken to prevent use of 

methyl parathion in homes. For outdoor us~, protective measures 

required for other organophosphate and carbamate. insecticides 

should be considered. Special attention should be given to 

protecting pesticide handl-ers and prevent·ing spray drift. 

cc : Correspondence. 

Methyl parathion file (chemical rio. 053501) 

SRRD - Emily Mitchell (7508W) 

RDI: BRSrSci: SHummel: