Chemicals, EHS Administration, Reporting

OIG Says Trump EPA Ignored Guidelines in Assessing Pesticide Cancer Risks

On July 20, 2022, the EPA Office of Inspector General (OIG) released a report critical of EPA management practices, entitled “The EPA Needs to Improve the Transparency of Its Cancer-Assessment Process for Pesticides.”

The controversy uncovered by the report centers around the use of 1,3-dichloropropene (1,3-D) pesticide. The report concludes the Trump Administration EPA did not adhere to standard operating procedures and requirements for 1,3-D pesticide, “which undermines public confidence in and the transparency of the Agency’s scientific approaches to prevent unreasonable impacts on human health.”


1,3-D pesticide was first registered as a pesticide in 1954. It is generally utilized as a soil fumigant to control roundworms.

The pesticide is primarily used on potato, tobacco, strawberry, peanut, and tomato crops. EPA data suggests that 1,3-D use increased almost 40% from 2001 to 2017.

The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) requires the EPA to review every pesticide registration no later than 15 years after the active ingredient’s initial registration to determine whether the pesticide continues to perform its intended function without unreasonable adverse effects on human health and the environment.

“From 1985 through 2018, the EPA classified 1,3-D as ‘Likely to be Carcinogenic to Humans,’ which means that there is evidence of carcinogenic potential in two or more different species, sexes, or strains, or from two or more different sites or exposure routes,” states the OIG report. “With this classification, the EPA quantified 1,3-D’s cancer risk, which was used to identify acceptable exposure levels, at the one-in-10,000 excess lifetime cancer risk level, meaning that if 10,000 people are exposed to the same concentration of this chemical over an estimated lifetime, one additional person would likely develop cancer from this exposure.”

In 2019, 1,3-D’s classification was changed to “Suggestive Evidence of Carcinogenic Potential,” which means that there is evidence of tumors in only a single animal cancer study or only at a single dose. This cancer reclassification of the pesticide means the EPA no longer quantifies the cancer risk of the chemical and acceptable exposure limits are based only on noncancerous health effects, which allows the long-term exposure level considered an unreasonable risk to humans to increase 90-fold.

Faulty assessment

The OIG report finds the following deficiencies in the EPA’s assessment:

  • The EPA used two scientific approaches in its cancer-assessment process for 1,3-D, even though it did not have guidance outlining how to use those approaches.
  • The agency did not adhere to docketing and transparency requirements to provide the public and stakeholders with information that may have influenced the EPA’s cancer-assessment decision.
  • The EPA did not follow its literature-search procedures, and neglected to document its review of all health effects data that may have impacted the results of the 1,3-D draft human health risk assessment, which is informed by the cancer assessment.
  • The EPA’s Cancer Assessment Review Committee (CARC) did not adhere to internal peer review standards, the EPA’s Peer Review Handbook and the Office of Management and Budget’s (OMB) guidance on peer review, in the areas of composition, independence, and expertise.

“These deficiencies undermined the scientific credibility of the 1,3-D cancer assessment, which led to questioning by multiple stakeholders,” states the OIG report. “An external peer review would have improved the credibility of the 1,3-D cancer assessment.”

OIG recommendations

To address the assessment deficiencies, the OIG recommends that the EPA:

  1. Issue guidance on when and how to conduct the two scientific approaches used in its cancer-assessment process for 1,3-D.
  2. Update the docket for 1,3-D to include all required materials, including minutes and a list of participants, for meetings between the EPA and the registrant related to the 1,3-D pesticide-registration review and cancer assessment.
  3. Issue guidance to clarify when to docket meetings related to a registration for other related activities that occur concurrent to the pesticide registration review process, such as the cancer reassessment process.
  4. Conduct a comprehensive literature search that identifies all published scientific studies concerning the potential carcinogenicity of 1,3-D, including a methodology to reconcile inconsistencies in the scientific data, and publish the results of the literature search and reconciliations.
  5. Update the CARC standard operating procedures to comply with the EPA’s Office of Pesticide Programs’ (OPP’s) literature-search standard operating procedures and the broader quality principles in the OMB’s 2002 Information Quality Guidelines.
  6. Issue procedures to document the composition, independence, and expertise of the CARC and its members, as well as procedures to determine whether applicable internal peer review standards are being met.
  7. Conduct an external peer review on the 1,3-D cancer-risk assessment.
  8. Issue specific criteria requiring external peer review of OPP risk assessments that use scientifically or technically novel approaches or that are likely to have precedent-setting influence on future risk assessments, in accordance with the OMB’s Final Information Quality Bulletin for Peer Review.

The EPA worked with the OIG to resolve recommendations 2–6 and 8 above with corrective actions pending. Recommendations 1 and 7 are currently unresolved. 

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