Acute Occupational Pesticide-Related Illness and Injury — United States, 2007–2010

Geoffrey M. Calvert, MD1

John Beckman2

Joanne Bonnar Prado, MPH3

Heidi Bojes, PhD4

Prakash Mulay, MPH5

Michelle Lackovic, MPH6

Justin Waltz, MPH7

Abby Schwartz, MPH8

Yvette Mitchell, MS9

Stephanie Moraga-McHaley, MS10

Kathy Leinenkugel, MPA11

Sheila Higgins, MPH12

1Division of Surveillance, Hazard Evaluations, and Field Studies, National Institute for Occupational Safety and Health, CDC, Cincinnati, Ohio

2Public Health Institute and Occupational Health Branch, California Department of Public Health, Richmond, California

3Office of Environmental Public Health Sciences, Washington State Department of Health, Olympia, Washington

4Environmental and Injury Epidemiology and Toxicology Unit, Texas Department of State Health Services, Austin, Texas

5Florida Department of Health, Tallahassee, Florida

6Louisiana Department of Health and Hospitals, New Orleans, Louisiana

7Center for Health Protection, Oregon Public Health Division, Oregon Health Authority, Portland, Oregon

8Division of Environmental Health, Michigan Department of Health and Human Services, Lansing, Michigan

9Bureau of Occupational Health and Injury Prevention, New York State Department of Health, Troy, New York

10New Mexico Department of Health, Albuquerque, New Mexico

11Iowa Department of Public Health, Des Moines, Iowa

12North Carolina Department of Health and Human Services, Raleigh, North Carolina

Corresponding author: Geoffrey M. Calvert, Division of Surveillance, Hazard Evaluations, and Field Studies, National Institute for Occupational Safety and Health, CDC. Telephone: 513-841-4448; e-mail: jac6@cdc.gov.

Preface

CDC's National Institute for Occupational Safety and Health (NIOSH) collects data on acute pesticide-related illnesses and injuries reported by 11 states (California, Florida, Iowa, Louisiana, Michigan, North Carolina, New Mexico [2007–2008 only], New York, Oregon, Texas, and Washington). This report summarizes data on illnesses and injuries arising from occupational exposure to conventional pesticides during 2007–2010. This report is a part of the first-ever Summary of Notifiable Noninfectious Conditions and Disease Outbreaks, which encompasses various surveillance years but is being published in 2015 (1). The Summary of Notifiable Noninfectious Conditions and Disease Outbreaks appears in the same volume of MMWR as the annual Summary of Notifiable Infectious Diseases (2).

Background

Pesticides are substances or mixtures of substances intended to prevent, destroy, repel, or mitigate pests (e.g., insects, rodents, fungi, and weeds). In 2007, the year with the most currently available data, an estimated 2.1 billion pounds of conventional pesticides were used in the United States (3), which represents approximately 22% of the entire worldwide use of these pesticides. Conventional pesticides include insecticides, herbicides, fungicides, and fumigants and exclude chlorine, hypochlorites, and biocides.

The toxicity of pesticides continues to raise public concern and is the focus of much media attention. The benefits of pesticides are well recognized and primarily include their role in protecting the food supply and in controlling disease vectors (4). However, no form of pest control is perfectly safe. Tracking the associated health effects of pesticides can help ensure that no pesticides pose an unreasonable burden (5). As such, public health surveillance of acute pesticide-related illness and injury serves a vital societal role by assessing the magnitude and characteristics of this condition. Surveillance of acute pesticide-related illness and injury has been endorsed by several professional organizations and federal agencies including the American Medical Association (6), the Council of State and Territorial Epidemiologists (7), NIOSH (8), and the U.S. Government Accountability Office (9). To address the need for public health surveillance of acute pesticide-related illness and injury, NIOSH established such a surveillance program in 1987.

Pesticide products must pass an extensive battery of testing prior to being registered by the U.S. Environmental Protection Agency (EPA). This testing forms the basis for the human health and environmental risk assessments conducted by EPA that guide identification of the conditions under which a pesticide can be used. These conditions of use are reflected in pesticide product labeling. Compliance with these use conditions are expected to prevent unreasonable adverse effects to human health and the environment. To verify the real-world effectiveness of pesticide product labeling in preventing adverse human health effects, findings from acute pesticide-related illness and injury surveillance systems are reviewed. These surveillance data assist EPA to determine whether labeling is effective or if labeling improvements are needed. When adverse health effects occur despite adherence to label instructions, and if EPA determines the magnitude to be unreasonable, EPA requires that interventions be instituted that involve changing pesticide use practices and/or modifying regulatory measures (10). Acute pesticide-related illness and injury also can occur because of a lack of compliance with existing pesticide regulations. The appropriate interventions for these cases include enhanced education and enforcement.

Data Sources

Since 1987, NIOSH has conducted surveillance of acute occupational pesticide-related illness and injury through the Sentinel Event Notification System for Occupational Risks (SENSOR)–Pesticides program. Detailed information on this program is available at http://www.cdc.gov/niosh/topics/pesticides/overview.html. During 2007–2010, a total of 11 states (California, Florida, Iowa, Louisiana, Michigan, North Carolina, New Mexico [2007–2008 only], New York, Oregon, Texas, and Washington) participated in the SENSOR-Pesticides program.

Case ascertainment sources used by the state programs include poison control centers, other government agencies (e.g., state departments of agriculture), workers' compensation documents, and physician reports. In some states, other sources (e.g., medical record reviews, news reports, and reports from worker representatives) infrequently identify cases (11). Staff from some state surveillance programs attempt to interview persons with illness or injury to obtain more details about the event. All states use standardized variables to code available information about a case systematically (11).

Persons are considered to have a pesticide-related illness or injury if they became ill or injured soon (i.e., within seconds to hours) after exposure to one or more pesticides. An illness and injury is considered occupational if the pesticide exposure occurred at the affected person's place of work. Agricultural cases are defined as cases occurring among persons employed in an industry with one of the following Census Industry Codes (CICs): agricultural production, excluding livestock (1990 CIC: 010; 2002 CIC: 0170); agricultural production, including livestock (1990 CIC: 011; 2002 CIC: 0180); and agricultural services (1990 CIC: 030; 2002 CIC: 0290). All other occupational cases with a known industry code are defined as "nonagricultural" cases.

The SENSOR-Pesticides case definition has been described in detail elsewhere (11). The definition requires information about pesticide exposure and health effects, which is compared with the known toxicology of the pesticide. Cases in the SENSOR-Pesticides program are categorized as definite, probable, possible, and suspicious on the basis of the level of known detail on the case. Cases are defined as definite exclusively on the basis of objective data about exposure and health effects (e.g., residues were measured to confirm exposure and health effects were observed by the examining clinician). Cases are defined as probable on the basis of a mix of objective and self-reported data. Cases are defined as possible on the basis of self-reported exposure and health effects data. Suspicious cases arise when the toxicologic information is insufficient to determine a causal relationship between pesticide exposure and illness, often because the given pesticide is relatively new and limited toxicologic data involving humans exist. Often reports of illness and injury are not categorized as definite, probable, possible, or suspicious because insufficient information is available about the circumstances of the exposure event or because the available evidence suggests that the pesticide exposure was either unrelated to or was unlikely to have caused the observed health effects. These "insufficient information," "unrelated," and "unlikely" exposures are not included in the analysis of confirmed illness and injury cases provided in this report.

Illness and injury severity was categorized into four groups using standardized criteria for state-based surveillance programs (11). In low-severity cases, the condition usually resolves without treatment and <3 days are lost from work. In moderate-severity cases, the condition is not life-threatening but does require medical treatment, no residual impairment is expected, and time lost from work is ≤5 days. In high-severity cases, the condition is life-threatening, requires hospitalization, often has >5 days lost from work, and might result in permanent impairment. Fatal cases of pesticide poisoning were placed in a separate category.

To calculate incidence rates (IRs) of acute occupational pesticide-related illness and injury, NIOSH obtained denominator data (i.e., hours worked) from the U.S. Current Population Survey (CPS) (12). These data were used to derive full time equivalent (FTE) estimates, with one FTE equal to 2,000 hours worked. Denominator data correspond to the states and time periods of numerator availability.

This report includes only acute pesticide-related illness and injury arising from occupational exposures. Furthermore, nine occupational cases involving exposures with suicidal or homicidal intent were excluded. During 2007–2010, of the 6,841 cases reported to SENSOR-Pesticides, 2,014 (29%) were from occupational exposures and are included in the analyses.

Interpreting Data

For multiple reasons, the counts and rates provided in this report (Tables 1 and 2) are likely to be underestimates of the actual magnitude of acute occupational pesticide-related illness and injury (13). Many cases of persons with pesticide-related illness or injury are never ascertained because they neither seek medical care nor call appropriate authorities. Furthermore, because the signs and symptoms of acute pesticide-related illnesses are not pathognomonic, and because most health-care professionals are not acquainted with the recognition and management of these illnesses, many persons who seek medical care might not receive an accurate diagnosis. Even among those who do receive an accurate diagnosis, many are not reported to state surveillance systems, despite the fact that the participating states all have mandatory reporting requirements for occupational pesticide-related illness and injury (5). For these reasons, the counts and rates provided in this report must be considered minimum estimates. In contrast, some persons might have been categorized incorrectly as having acute occupational pesticide-related illness because symptoms for acute illnesses associated with pesticides are nonspecific and not pathognomonic, and diagnostic tests are either not available or rarely performed. In addition, rates of pesticide illness and injury might have been affected by inaccurate estimates of the agricultural industry population. Many workers in this industry are difficult to count because of the transient employment of seasonal and migrant farmworkers, and those with undocumented U.S. immigrant status tend to avoid government contact (14). Furthermore, the denominator inaccuracies might vary across states because some states might be more likely to have agricultural workers whose usual residence is elsewhere. Agricultural workers are not included in CPS state population estimates of those states in which they reside only temporarily (15).

Although the incidence rates for acute occupational pesticide-related illness and injury were highest in Washington, this finding might not necessarily mean that pesticide exposures are more hazardous or more prevalent in that state. Washington has stronger protections for agricultural workers and a larger and more robust pesticide illness and injury surveillance program than other states, thereby accounting for some of the differences in incidence rates. As an example of stronger worker protections, Washington gives farmworkers the right to organize and bargain collectively and requires cholinesterase monitoring for some pesticide handlers (10). These protections might make farmworkers in Washington less hesitant to seek medical care for pesticide illness and injury. In addition, Washington has a larger number of surveillance program staff (3.75 FTEs versus an average of 1.3), and all but one are bilingual Spanish/English speakers. The odds of identifying agricultural worker cases might be improved when surveillance programs have a bilingual staff of ample size because agricultural workers are often Spanish-speaking. Although workers' compensation systems can be an important source of case reports, only two states (California and Washington) received reports from this source during 2007–2010. The workers' compensation system can be an especially useful reporting source when it is organized as in Washington. For example, Washington is the only state whose workers' compensation system covers the first visit for any suspected work-related illness or injury, even if the illness or injury is determined not to be work-related. In addition, unless Washington employers are able to self-insure, workers' compensation insurance is provided by an exclusive state-fund operated by the state's Department of Labor and Industries. There are no other private workers' compensation insurers in the state. This avoids problems that can occur in other states when state authorities either do not receive information from private workers' compensation insurers or process such information incorrectly. No other SENSOR-Pesticides state provides workers' compensation insurance through an exclusive state fund. For all these reasons, case estimates from Washington might be more accurate than those in other states, although even these estimates likely underestimate the actual level of occupational pesticide-related illness and injury.

The pesticides most often implicated in acute occupational pesticide-related illness and injury are listed (Table 3). Data are stratified by whether the affected person was exposed to a single substance (i.e., active ingredient). When affected persons were exposed to a single substance, it is very likely that that substance was responsible for illness or injury. However, this might not be so for persons who were exposed to multiple substances because one of the other substances might have produced the illness or injury. Furthermore, pesticide products also contain solvents and other nonactive ingredients, some of which might produce illness. Because the identity of inert ingredients present in pesticide products is almost never available, attribution of illness to these ingredients is not possible. In addition, only illnesses and injuries caused by exposure to conventional pesticides are included in this report. Illnesses and injuries caused by chlorine, hypochlorites, and other disinfectants are not included in this report because not all states capture such illnesses (often because of resource constraints) and therefore including them would make the rate estimates not comparable across the 11 states.

Methods for Identifying Acute Occupational Pesticide-Related Illness and Injury

All 11 states that participate in the SENSOR-Pesticides program require physicians to report confirmed and suspected cases of pesticide-related illness and injury to state health authorities. Besides identifying, classifying, and tabulating pesticide poisoning cases, states periodically perform in-depth investigations of pesticide-related events, and develop interventions aimed at particular industries or pesticide hazards.

Publication Criteria

Persons meet the publication criteria if they met the case definition and were exposed to conventional pesticides at their place of work during January 1, 2007–December 31, 2010.

Highlights

During 2007–2010, a total of 2,014 cases of acute occupational pesticide-related illness and injury were identified in 11 states (Table 1). Rates of illness and injury among agricultural industry workers (18.4/100,000) were 37 times greater than the rates for nonagricultural workers (0.5/100,000). Rates were found to be highest in Washington. Most affected persons were exposed to insecticides or herbicides (Table 2). Among persons who were exposed to insecticides, the chemical classes most often involved were pyrethroids, organophosphates, and pyrethrins (Table 3). Among persons exposed to herbicides, the specific herbicides most commonly involved were glyphosate and the dipyridyls (i.e., paraquat and diquat). A total of 81% of cases were classified as low severity, 17% were moderate severity, and 1% were high severity. One affected person died.

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