Chlorpyrifos Preliminary Volatilization Assessment Finds Risks to Children

EPA Requests Comment to Address Uncertainties

Washington, DC–(ENEWSPF)–February 21, 2013.  On February 6, the U.S. Environmental Protection Agency (EPA) released its preliminary volatilization assessment for the registration review of chlorpyrifos, finding that vapor phase chlorpyrifos may be emitted from treated fields at levels resulting in exposure to children and others who live, work, attend school, or otherwise spend time nearby. In some circumstances, these bystanders may be exposed to chlorpyrifos and/or the transformation product chlorpyrifos-oxon at concentrations that could cause adverse effects. Citing uncertainties, the agency is requesting comments by March 8, 2013 on the potential risks to children and other bystanders from volatilization of chlorpyrifos from treated crops.

EPA’s preliminary volatilization assessment is also in response to a petition filed by the Natural Resources Defense Council (NRDC) and the Pesticide Action Network North America (PAN) in 2007, which requested that the agency revoke all tolerances and cancel all registrations for chlorpyrifos. In a letter to NRDC and to PAN dated January 25, 2013, updating these groups on EPA’s response to their September 12, 2007 joint petition regarding chlorpyrifos, EPA stated that, “This assessment represents a significant advancement in the evaluation of pesticide risks, as it will be the first probabilistic assessment of the risks posed by the post-application volatilization of a semi-volatile pesticide.” EPA further stated that it is “critical to involve the public in the development of this assessment before it is finalized,” given “the groundbreaking nature of the new assessment and its potential for use in guiding additional risk mitigation.” The implications of the draft assessment and possible regulatory pathways forward could be significant, particularly with regard to pesticide spray drift.

If the final, more refined, chlorpyrifos volatility assessment indicates that risks are similar to those found in the preliminary evaluation, EPA anticipates that it may be necessary to take action to reduce bystander risks. With more information, however, the agency’s preliminary assessment could be refined and result in lower exposure and risk estimates. Last year, EPA announced new mitigation measures to reduce bystander exposure to chlorpyrifos drift from agricultural fields, including the use of buffer zones for residential areas, schools, hospitals, etc. Chlorpyrifos was voluntarily withdrawn by manufacturers from residential use after EPA determined that cumulative exposure resulted in serious adverse health outcomes, especially for children. Short-term effects of exposure to chlorpyrifos include chest tightness, blurred vision, headaches, coughing and wheezing, weakness, nausea and vomiting, coma, seizures, and even death.

The preliminary evaluation of the potential risks from volatilization of chlorpyrifos supplements the EPA’s June 2011 preliminary human health risk assessment for the registration review of chlorpyrifos, and July 2012 spray drift assessment. The chlorpyrifos volatilization assessment includes approaches that the agency has used previously to assess inhalation exposures of fumigant pesticides. The assessment also is consistent with recommendations of the December 2009 FIFRA Scientific Advisory Panel meeting on the scientific issues associated with field volatilization of conventional pesticides.

Chlorpyrifos is a neurotoxic insecticide that was banned from residential applications after EPA determined that cumulative exposure resulted in serious adverse health outcomes, especially for children. Prenatal and early childhood exposure has been linked to low birth weights, developmental delays, ADHD and other health effects. Beyond Pesticides has cited EPA’s action regarding the organophosphate chlorpyrifos as a classic failure of the risk assessment process under the Food Quality Protection Act (FQPA) –a failure that is repeated over and over again in agency chemical regulation decisions. The purpose of FQPA is to protect infants and children from pesticides, taking into account the potential for pre- and post-natal toxicity via any route of exposure, including exposures through structural and landscape uses, diet, and water. Advocates have pointed to chlorpyrifos as the poster child for why risk assessment does not work to protect the public, workers and the environment, given that safer practices, including organic practices and products are increasingly available in the marketplace.

By focusing on risk reduction strategies to come up with “acceptable,” but unnecessary, rates of illness across the population, EPA continues to underestimate the impact of the chemical’s continued widespread use in agriculture. Chlorpyrifos is a frequent water contaminant and a long range contaminant, exposing communities and contaminating pristine areas far from where it was applied. Residues in food and water continue to put public health at risk. Volatilization drift—the evaporation of the pesticide after application—is also part of the problem for chlorpyrifos, but the new restrictions do not take into account volatilization drift. EPA noted its intention to address volatilization drift when the chlorpyrifos risk assessment is finalized in 2014.

Take Action: Comments on the preliminary volatilization assessment are due March 8, 2013. EPA states that after reviewing comments received during the public comment period, it will issue a revised volatilization assessment, explain any changes to the preliminary volatilization assessment, respond to comments, and evaluate the need for risk mitigation for chlorpyrifos. The preliminary assessment is available online, and the docket is available online.

The chlorpyrifos preliminary volatility assessment , guide to commenters , and related documents are available in docket EPA-HQ-OPP-2008-0850 at

All unattributed positions and opinions in this piece are those of Beyond Pesticides.