Pesticide-Related Illness

Definition: “Pesticide-related illness (referred to as pesticide poisoning in WAC 246-100-217)” means the disturbance of function, damage to structure, or illness in humans resulting from the inhalation, absorption, ingestion of, or contact with any pesticide. For this analysis we define a case as a pesticide-related illness which was classified as “definitely”, “probably” or “possibly” related to pesticide exposure. Suicides, attempted suicides and intentional malicious use were excluded.

Washington is one of eight states which actively track and investigate pesticide-related illnesses. Approximately 40% of all identified cases occurred among workers in agricultural settings, and about 80% of these were men. The total number of cases and number in occupational / agricultural settings has remained relatively constant over the past five years.

The use of pesticides has expanded greatly since World War II. There are now more than 20,000 registered pesticide products derived from more than 600 active ingredients. According to the United States Environmental Protection Agency (EPA), agricultural usage of pesticides peaked around 1980 and now accounts for approximately 80% of total pesticide use. In addition, an estimated three-fourths of all US households use some form of pesticides.1 In Washington, 50% of households report having used pesticides outside their homes and 16% report indoor use during the past year.

Public concern over the risks from pesticides has increased during the past three decades. These concerns have created a growing demand for data on the public health impacts of pesticide exposure. Although about half the states have rules requiring some form of reporting of pesticide exposure and illness, Washington is one of only eight states that routinely conduct comprehensive case investigations and surveillance activities.

The most recent statistics on pesticide poisonings nationwide (1992) indicate there were 10,000 to 20,000 physician-treated pesticide illnesses and injuries among agricultural workers.2 However, the actual extent of this problem is difficult to estimate as pesticide illnesses and injuries are very complex and difficult to track. Some farmworkers are reluctant to report incidents and seek treatment, or might not recognize an illness as being pesticide-related. Pesticide products can be composed of single pesticides or mixtures of pesticides and other ingredients. Depending upon the extent of exposure and toxicity of the pesticide, people can manifest a wide variety of health problems, ranging from non-specific signs and symptoms that mimic the flu to serious systemic effects that, under certain circumstances, can result in death. The severity of illness can be influenced by individual susceptibilities. Children and the elderly are among those at higher risk of serious effects. There is particular concern about farmworkers and their children, many of whom face chronic exposure to a variety of products3.

The EPA requires that pesticide products go through extensive testing prior to marketing, yet this testing does not address all environmental conditions, mixtures of chemicals, and chronic exposure patterns that can occur in actual use. Illness surveillance can provide important early warning of potential problems that might not be detected by manufacturer testing.

Since 1990, the Washington State Department of Health (DOH) has maintained the Pesticide Illness Monitoring System (PIMS) to track pesticide related illnesses and injuries. Data collected through PIMS have identified high-risk pesticides and use practices for regulatory change, intervention activities, and education.

Pesticide-related illness is one of the few environmental health problems for which health data are available.

Hazard Indicators. Pesticides are widely used in Washington. However, information on the amount and types of pesticides used are not available because there are no regulations requiring reporting of pesticide use.

Exposure Indicators. Exposure to some pesticides can be measured by biomarkers in blood or urine. One of the most common biomarkers for exposure to organophosphate pesticides is cholinesterase activity in the blood. The Department of Labor and Industries recommends occupational cholinesterase monitoring, and is currently developing rules to require cholinesterase monitoring for agricultural mixers and loaders of class I organophosphate and carbamate insecticides.