Human Health Effects
The effects of acute fumigant poisoning vary depending on the fumigant and include eye irritation, sore throat, headaches, nausea, vomiting, breathing difficulties and aggravated asthma, and neurological effects such as convulsions, dizziness, or tremors. Chronic effects linked to fumigant exposure include increased incidence of some cancers, asthma and other respiratory problems, neurological deficiencies, and birth defects. (see Toxicity of Soil Fumigants below).
Fumigants Responsible for Poisonings At Home and On the Job
Farmworkers face the greatest risks of exposure to soil fumigants and consequent health impacts. Workers applying the chemicals are most vulnerable to exposures, as is the case with all pesticides, but drift-prone soil fumigants also present special concerns for workers in adjacent fields. These exposure risks may continue for several weeks after the pesticides are applied, but are highest in the first 3-4 days after the application. Metam sodium, the pesticide responsible for multiple acute poisonings in California, is midway through EPA’s risk assessment process, in which the agency has found that near-field exposures from currently legal applications were substantially higher than EPA’s “acceptable” concentrations.
Communities near agricultural fields also face serious risks of acute pesticide poisoning from drifting fumigants. In California’s Central Valley several fumigant drift incidents have poisoned entire communities. In October 2003, a plume of chloropicrin drifted into the Central Valley community of Lamont after being applied to a nearby onion field. One hundred and fifty residents were poisoned. Despite the widespread illness, application of the pesticide was continued the next day and a hundred more people were affected. In Earlimart in 1999 an entire neighborhood was poisoned by a metam sodium application, resulting in the evacuation of 150 people from their homes. In May 2004, another mass poisoning from a metam sodium application occurred in Arvin, California, affecting 270 people. These incidents are particularly egregious because they affect all community members, including children, the elderly and other particularly vulnerable groups. One Earlimart resident recalled that she first noticed something was wrong when her infant son’s eyes began to tear. Long lasting effects have been observed from these incidents, including chronic bronchitis, damaged eyesight, and asthma.
Toxicity of Soil Fumigants
| Fumigant Pesticide | Symptoms of Poisoning [1] | Types of Toxicity |
| Methyl bromide | Severe irritation of lower respiratory tract, central nervous system depression and convulsions, fluid and/or bleeding in the lungs which may cause pneumonia. Early symptoms of acute poisoning include headache, dizziness, nausea, vomiting, tremor, slurred speech and incoordination. Severe poisoning may result in seizures, incoordination, muscle weakness, tremors, behavioral disturbances and diminshed reflexes. Skin contact causes severe burning, itching, blister formation and necrosis. |
Highly acutely toxic [2] Developmental toxicant [3] Neurotoxicant [4] |
|
Metam sodium [5]
|
Headache, dizziness, irritation of eyes, nose and throat, nausea, diarrhea, shorness of breath, chest tightness. Symptoms delayed a week or more may include: weakness, diarrhea, cough and rash. |
MITC/MIC/H2S are highly acutely toxic [2] Metam sodium is a developmental toxicant [3] and probable carcinogen [7] |
| Chloropicrin | Severe irritation of skin, eyes, and respiratory tract; nausea and vomiting. |
Highly acutely toxic [2] Chronic respiratory damage [8] |
| 1,3-Dichloropropene (Telone) | Irritation of skin and respiratory tract, nausea, vomiting, headache, central nervous system depression and multiorgan system failure including severe bleeding disorders, high blood sugar, acute kidney and liver failure, and respiratory distress. |
Highly acutely toxic [2] |
| Methyl iodide [9] | Dizziness, sleepiness, nausea, diarrhea, slurred speech, lack of coordination and muscle convulsions. [10] |
Highly acutely toxic [2] Carcinogen [3] |
Airborne Fumigants Create Hazardous Conditions Far from the Application
Acute poisoning incidents are not the only health concern. Fumigant drift has also been measured in air far from application sites, sometimes at levels above those considered “acceptable” for longer-term seasonal exposures by EPA or the California Department of Pesticide Regulation. In 2003, PANNA compared these “acceptable” air concentrations for several fumigants with concentrations of pesticides measured in air by the California Air Resources Board. PANNA’s analysis, published in Secondhand Pesticides: Airborne Pesticide Drift in California (available on the PANNA web site ) indicates that many Californians in areas of high fumigant use are routinely exposed to levels of airborne fumigants that may present health risks, even if they don’t live near an application site.
Fumigants also have significant impacts on air quality in regions where they are used extensively. In California’s Central Valley and in Ventura County on the south coast of California, fumigants are responsible for the majority of the pesticide-related air pollution. Most fumigant pesticides are Volatile Organic Compounds (VOCs) that mix with air and sunlight to form ground-level ozone, an ingredient of air pollution known to cause and exacerbate asthma and other respiratory diseases.[11]
- Unless otherwise referenced, symptoms of poisoning are from J.R. Reigart, J.R. Roberts, Recognition and Management of Pesticide Poisonings, 5th edition, U.S. EPA, 1999.
- Highly acutely toxic chemicals cause immediate illness at low exposure levels. U.S. EPA classified these chemicals as Category I toxicants.
- Included in the California Proposition 65 list of known carcinogens, developmental or reproductive toxicants.
- Included in the U.S. EPA Toxics Release Inventory (TRI) list of neurotoxicants. Hazard Information on Toxic Chemicals Added to EPCRA Section 313 under Chemical Expansion, U.S. EPA.
- Metam potassium and dazomet are less widely used soil fumigants that also break down into MITC, MIC, and H2S.
- MITC, MIC, and H2S are gaseous breakdown products of metam sodium, metam potassium, and dazomet.
- Ranked by U.S. EPA as a B2 (Probable) carcinogen. See PesticideInfo.org for an explanation of U.S. EPA's cancer classification systems.
- Chloropicrin Chronic Toxicity Summary, California Office of Environmental Health Hazard Assessment, December 2001.
- Not yet registered for pesticidal use, but is likely to be used as a drop-in replacement for methyl bromide.
- Methyl Iodide Product Information, Iodine.com.
- Summary of 1990-2000 VOC Emissions Inventory Data, Version 01.12, memorandum from F. Spurlock to J. Sanders, California Department of Pesticide Regulation, February 4, 2002.
