Home › Campaigns › Protect from Fumigants

Fumigant Pesticides Review

The Fumigant Cluster Assessment Decision

As part of the re-registration of older pesticides mandated by the Food Quality Protection Act, the U.S. Environmental Protection Agency (EPA) conducted a simultaneous review of several soil fumigant pesticides in a process that they call the "Fumigant Cluster Assessment." Fumigants are gases or highly volatile liquids or solids that are injected or dripped into soil to sterilize a field before planting. They are also used to fumigate stored foods, greenhouses and imported goods.

On July 10th, 2008 U.S. EPA announced their decision, and on July 17th it was published in the Federal Register. The decision affects all the fumigants but methyl iodide, which was only recently registered, and Telone, which was reviewed more recently than the others. EPA will revisit all the registered fumigants again in 2013.

 


Source: U.S. EPA [6]


EPA's decision includes many "mitigations" that PANNA believes will substantially reduce, but not eliminate, fumigant poisonings. Among the most significant are:

  • buffer zones around fumigated fields
  • posting at the edge of the buffer zones 
  • notification of state agencies (or tribal agencies) in advance of fumigation
  • strengthened worker protections

Although these mitigations are very welcome, evidence from models and poisoning incidents suggests that the buffer zones EPA has chosen are not sufficiently large to eliminate fumigant poisonings. For example, in the Yerington, Nevada poisoning in the fall of 2007, over 120 workers in a neighboring field were poisoned despite being 1/3 of a mile from the fumigated field. Officials investigating the incident cleared the grower of wrongdoing and instead blamed a weather inversion. Furthermore they characterized this as a rare occurrence. In fact, weather inversions are a frequent occurrence in the evenings in agricultural valleys, and they are a factor in many of the fumigant mass poisonings that have been investigated. EPA has attempted to address this by imposing restrictions on the weather conditions under which fumigants can be applied.

When accidents do happen, there is often a lack of understanding as to the probable cause. Posting at the edge of the buffer zones will help with this in two ways: (1) it will help keep people out of the buffer zones, which could have no demarcation at all if it weren't for this mitigation, and (2) it will help people living and working near fields to be informed and be prepared. Notification complements posing and the notification requirement will help enforcement officials and emergency personnel monitor compliance and respond to accidents.

The worker protections include adding tarp cutters to the "fumigant handler" category, extending the re-entry interval to five days, and beefing up the procedures for the use of masks. These measures will significantly reduce worker exposure and injuries.

EPA's final decision is the culmination of a four-year process involving many people and organizations. Communities and farmworkers who live and work near fumigated fields and advocates on their behalf can be proud that many of the measures that they know are critical to caring for people's health and safety found their way into EPA's final decision. EPA's decision is final, but they will nonetheless collect comments for 60 days following publication in the federal register. The comment period closes September 15th. They acknowledge the possibility of fine tuning the decision and this would result in an amended decision. This is a good time to read the details of EPA's decision and make sure that no argument that has been previously made has been missed.

More details on EPA's fumigant cluster assessment decision, can be found in PANNA's newsroom and on EPA's website. For those interested in the process leading up to the decision, addtional information is below.

Process Leading up to the Final Decision

Preliminary risk assessments for five currently registered fumigant pesticides—methyl bromide, metam sodium, dazomet, 1,3-dichloropropene (Telone) and chloropicrin—were released for public comment in 2005 and 2006. A new fumigant, methyl iodide, see article,is also being registered.

EPA is evaluating these pesticides as a group because they share common issues related to exposure and toxicity. [1]

Revised risk assessments for the five currently registered fumigants were released on May 2, 2007, with a public comment period that closed on November 3, 2007. A summary of the mitigation options being considered by EPA to reduce exposures to fumigants can be found on their website.

You can view the documents that the EPA is collecting on each fumigant:

It's nice that the process is transparent enough that anyone can view the documents on-line. However, most people — even many people who spend much of their time following pesticide issues — will quickly lose patience with the morass of detail that does not quickly illuminate the core issues.

To help cut through all this detail, the EPA held stakeholder meetings in different regions of the country — one in Ft. Myers,Florida on June 6, 2007 and one in Richland, Washington, on May 22,2007. In addition, in California, EPA staff attended meetings hosted by California's Department of Pesticide Regulation and by stakeholders. They also toured the parts of the San Joaquin Valley to meet community members that had been poisoned in large fumigant drift incidents,and to understand conditions first-hand.

 

 

EPA's fumigant cluster assessment process has two main opportunitiesfor public comment:

  • Phase 3, the "preliminary risk assessment," in which EPA's preliminary assessment of industry's toxicology and exposure assessment studies.
  • Phase 5, the "revised risk assessment" and "risk mitigations," in which EPA addresses comments from Phase 3 and asks for feedback on mitigation measures.

Phase 3 Comments

Phase 3 opened on July 13, 2005. EPA publish edits assessment of use patterns, toxicity data, exposure data, and existing alternatives for the five fumigant pesticides. These documents remain in the above dockets.

PANNA and many other organizations jointly submitted comments on the Phase 3 preliminary risk assessments. Methyl bromide"commodity" fumigation comments were also needed, and PANNA submitted comments on those too:

Exactly how much of a difference extensive technical comments make is a bit of a mystery. During the entire process, there has been a tendency in EPA's analyses to whittle away at established "safetyfactors" and to proceed to the next step of the process despite the identification of severe problems in the current step. For example, the exposure modeling shows that for a small but significant percentage of fumigations, the buffer zones EPA has been considering will not be large enough to keep toxic concentrations of fumigants out of communities that border fields. This is a fundamental failure in protecting public health. So far, it has not been addressed. Worker exposure is in a similarly problematic state.

Phase 5 Comments

Phase 5 of the process ended on November 3rd, 2007. PANNA was one of 30 organizations that collaborated on submission of detailed comments on the revised risk assessments:

Without these analyses, we would have far less understanding of the facts and no case in the public record.

However, technical comments by themselves are clearly not enough to make significant change. The case that has been made carries the weight of many allied organizations. It is supported by over 12,000 signers of a petition to EPA organized through PAN's Action Alert page and by the United Farm Workers. It is on the radar screen of legislative staff at the federal level. It is being considered by state regulators and local activists who have their own say in how fumigants are used in their regions, independent of U.S.EPA's decision. The issue is in the media, thanks in part to repeated accidents that poison so many people simultaneously that they deserve — andoccasionally get — front-page coverage.

Titanic forces pitting the drive for ever-cheaper commodities against public health, worker protection and environmental sustainability are clashing. The close of the Phase 5 comment period is a time to take stock and strategize for the health of people that live and work near fumigated fields, and for the quality and sustainability of the food supply.

Fumigant Drift Is Problematic

Fumigants are a class of highly volatile pesticides used to sterilize soil before planting. Highly toxic as well (see Toxicity of Soil Fumigants below), fumigants are designed to target a variety of insects, nematodes, fungi, and weeds and are applied more intensively than other pesticides. Application rates for soil fumigants are 50–400 pounds per acre compared to typical rates of 1–5 pounds per acre for other pesticides. Off-site drift is inevitable with fumigants because of these high application rates and the fact that these pesticides are gases or are very volatile liquids or solids that break down into gases after application.


Source: U.S. EPA [6]

A sprinkler application of metam sodium puts substantial
amounts of fumigant into the air.

Fumigants are applied by injection into the soil, by sprinkler application or via drip tape. After application, fields may be covered with a plastic tarp or a layer of water to “water in” the fumigant and slow its release from the field. Neither of these measures effectively prevents fumigant drift, which can pose risks to workers and nearby communities for several days and up to several weeks after the application. Three major fumigant drift incidents have occurred in California since 1999, with each incident resulting in hundreds made ill and forced to flee their homes to escape the incoming toxic cloud (see below).

As part of the Fumigant Cluster Assessment, EPA is considering the use of several computer models developed by pesticide industry consultants to estimate bystander exposure to fumigant drift.[2] These models are derived from the EPA’s Industrial Source Complex Short Term (ISCST3) air pollution modeling program and adapted to field fumigation conditions. PANNA’s preliminary review of the models questions whether the baseline air monitoring data used to construct the model adequately represent the conditions of most applications, as well as the performance of the model under very calm wind conditions (inversions), which have been a contributing factor to drift poisoning incidents.


Air monitoring results collected by the California Air Resources Board, consisting of actual exposure data and not derived from models, indicate that additional use restrictions will be necessary to reduce exposures below EPA’s “acceptable” levels for most fumigants. Ideally, the agency would put all of these chemicals on a phase-out timeline. In the meantime, substantial restrictions on their use such as expanding protection zones around application sites, limiting the area treated during a specific time period, reducing application rates, modifying application techniques, and/or capping the total amounts used in a particular geographic area over a specific time period should be implemented as soon as possible.


Source: PAN Archive

Methyl bromide is applied via soil injection followed by tarping the field to slow the release of the fumigant from the soil.


Source: PAN Archive

Application of Telone by a shank injection process. Note the shanks below the platform on which the worker is sitting in the top picture. The fumigant is released through these shanks when the platform is lowered, as in the bottom picture.

Fumigant Use Remains High

Crops for which soil fumigant use is heavy include strawberries, potatoes, tobacco, tomatoes, carrots, and peanuts, among others. These pesticides are also used in commodity fumigations to treat seeds, stored grains and fruits, and imported food and timber products and account for about 10% of total pesticide use in the U.S.[6] In California, where fumigant use has been tracked since the 1980s, total reported use of all fumigants has remained relatively constant over time (see Figure 1), although the pounds applied for each fumigant has changed. These use patterns suggest that most farmers are not changing their basic approach and continuing their reliance on pre-plant fumigation for soil pest control. Find out more about the history of fumigant use.

Economically viable non-chemical alternatives are available and already in use by organic and other sustainable agricultural practitioners. These alternatives include use of resistant cultivars, cultural methods such as crop rotation and use of cover crops as well as physical methods such as soil solarization (download PANNA's Technical Comment letter for more detail on alternatives). Providing research and incentives for widespread adoption of these methods should be a high priority for the U.S. Department of Agriculture and the EPA.

In California where pesticide use is tracked through a use reporting system, fumigant use has remained relatively constant over the years, although the mix of fumigants has changed.


Source: PANNA plot using CA DPR Pesticide Use Reporting data.

Fumigant use in California has remained relatively constant over the last 15 years.

In the U.S., fumigant use is especially heavy in just a few regions, including California and the Northwest and the Southeast, especially Florida. The U.S. EPA has published maps of estimated use for each fumigant pesticide currently in use, which we have reproduced here. EPA's full report on use patterns can be found in reference [7].


Source: U.S. EPA [7]


Source: U.S. EPA [7]


Source: U.S. EPA [7]


Source: U.S. EPA [7]

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]
Methyl isothiocyanate (MITC) [6]
Methyl isocyanate (MIC) [6]
Hydrogen sulfide (H2S) [6]

 

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]

Carcinogen [3, 7]

Methyl iodide [9] Dizziness, sleepiness, nausea, diarrhea, slurred speech, lack of coordination and muscle convulsions. [10]

Highly acutely toxic [2]

Carcinogen [3]

  1. 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.
  2. Highly acutely toxic chemicals cause immediate illness at low exposure levels. U.S. EPA classified these chemicals as Category I toxicants.
  3. Included in the California Proposition 65 list of known carcinogens, developmental or reproductive toxicants.
  4. 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.
  5. Metam potassium and dazomet are less widely used soil fumigants that also break down into MITC, MIC, and H2S.
  6. MITC, MIC, and H2S are gaseous breakdown products of metam sodium, metam potassium, and dazomet.
  7. Ranked by U.S. EPA as a B2 (Probable) carcinogen. See PesticideInfo.org for an explanation of U.S. EPA's cancer classification systems.
  8. Chloropicrin Chronic Toxicity Summary, California Office of Environmental Health Hazard Assessment, December 2001.
  9. Not yet registered for pesticidal use, but is likely to be used as a drop-in replacement for methyl bromide.
  10. Methyl Iodide Product Information, Iodine.com.

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. [5]

Resources

1 .Soil Fumigant Cluster Assessment Underway, U.S. EPA.

2. Fumigant Bystander Exposure Model Review, Meeting Minutes from August 24-27, 2004 and September 9-10, 2004 U.S. EPA Scientific Advisory Panel Meeting.

3. Preliminary Risk Assessment for Metam Sodium, U.S. EPA, E-Docket # OPP-2004-0159.

4. Guadalupe Hernandez, comment to U.S. EPA on Docket Control Number OPP-00730A, January 14, 2002; see fuller description of the incident in S. E. Kegley, A. Katten, M. Moses, Secondhand Pesticides: Airborne Pesticide Drift in California, Pesticide Action Network, California Rural Legal Assistance Foundation and Pesticide Education Center (San Francisco: 2003), p. 15.

5. 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.

6. This percentage is calculated based on national fumigant use (127 million pounds) and toal use of all pesticides (1,203 million pounds) reported in reference 7, including sulfur and petroleum oils, which is same as the basis for the percentages reported in California. Because reference 7 sums pesticide use both with and without sulfur and petroleum oils, this number can also be calulated using the sum without sulfur and petroleum oils (888 million pounds), which results in fumigant use accounting for 14% of the total U.S. pesticide use.

7. J. Becker, W. Chism, M. Kaul, D. Donaldson, T. Kiely, Overview of the Use and Usage of Soil Fumigants, U.S. EPA, June 15, 2005.

See the complete list ofresources about pesticide drift.

‹ Fumigant History: Still Poison After All These YearsupWhy U.S. EPA Should Reconsider its Methyl Iodide Decision ›

Back to top