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Committee to Advise on Reassessment and Transition

Note: This information is provided for reference purposes only. Although the information provided here was accurate and current when first created, it is now outdated.

Paper # 10

Developmental Neurotoxicity (DNT) Data Call-In

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What is the DNT Data Call-in?

• In August 1999, EPA informed the public that it was issuing data call-in notices to registrants of organophosphate pesticides. The data call-in would require submission of data on developmental neurotoxicity.
  Developmental neurotoxicity studies look at the way a pesticide affects the developing nervous system. Recent improvements in the basic study design coupled with refinements tailored on a case-by-case basis for each individual chemical will enhance the value of these data.
  EPA also is requiring additional data from acute and subchronic neurotoxicity screening studies.
  EPA, as always, supports the combining of study types, where possible, to maximize the amount of information gathered while minimizing animal testing. The developmental neurotoxicity study and the acute and subchronic neurotoxicity screens all lend themselves to being integrated into other study types.
  The results of the developmental and adult neurotoxicity testing in organophosphate pesticides are expected in 2001.
  Within the next two years, EPA expects to call in developmental (and adult, as appropriate) neurotoxicity testing data for other pesticides that have shown, or would be expected to show, neurotoxic effects.
  
• EPA has identified over 140 individual pesticides, belonging to several classes of chemicals, which are likely candidates for the data call-in. We would expect that other pesticides will be identified before the data call-in exercise is completed.

How will these studies be used?

• EPA will use the results of the DNT studies to characterize the pre- and post-natal toxicity of pesticides on the developing nervous system. These studies will show whether exposure to pesticides before or shortly after birth produce changes in nervous system development and function.
  EPA also is calling in data to characterize the effects of neurotoxic pesticides on the function of adult nervous systems. The Agency will compare the results of these studies to the results of the developmental neurotoxicity studies to determine whether developing nervous systems are more susceptible to the effects of neurotoxic pesticides than adult nervous systems (i.e., whether or not differences occur because of age or stage of nervous system development). The differences could be measurable (or quantitative) or descriptive (qualitative).
  
• EPA also will use these studies, along with other available information, in making FQPA safety factor decisions. EPA must use this factor to take into account pre- and post-natal toxicity and completeness of data with respect to exposure and toxicity to infants and children unless reliable information shows that a different factor may be used.

Next Steps

• EPA plans to issue a proposal in the Federal Register to amend its core data requirements for pesticides in Part 158 of Title 40 of the Code of Regulations. Among the proposed changes will be to make the DNT and certain other tests mandatory for all food use pesticides for which a tolerance (or tolerance exemption) must be determined. Currently, these studies are only required under certain conditions. We expect to publish a proposal in FY2001.

For more information:

• Contact the National Pesticide Telecommunications Network (800-858-7378; www.ace.orst.edu/info/nptn)
for information on the toxicity of pesticides.

• EPA’s pesticide homepage www.epa.gov/pesticides  has information about pesticide regulation as well as publications about pesticide issues for consumers.

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