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Variability in Nontarget Terrestrial Plant Studies Should Inform Endpoint Selection
Jane P Staveley1, John W Green2, Josie Nusz1
1Exponent, Chapel Hill, North Carolina, USA.
Summary
Pesticide testing on nontarget terrestrial plants (NTTP) shows high variability, making risk assessments challenging. Current methods struggle to reliably detect low-level effects, potentially overestimating environmental risks.
Area of Science:
- Environmental Toxicology
- Ecotoxicology
- Risk Assessment
Background:
- Nontarget terrestrial plant (NTTP) testing variability complicates pesticide risk assessment.
- Standardized protocols for ER25 and ER50 are established, but newer NOER and ER05 metrics face challenges.
- Statistically significant differences may not reflect biological relevance due to inherent variability.
Purpose of the Study:
- To assess variability in control results from pesticide NTTP studies.
- To identify causes of variation in control plant responses.
- To define the minimum detectable effect size in NTTP tests.
Main Methods:
- Analysis of historical data from ~100 seedling emergence and vegetative vigor guideline studies.
- Evaluation of control result variability across studies for each plant species.
- Investigation into potential causes for observed variations in control group performance.
Main Results:
- High inherent variability exists in control plant performance across studies.
- Current NTTP test designs and implementation make reliable ER05 estimation difficult.
- The ER05 value is not reliably estimable with existing methodologies.
Conclusions:
- The ER05 metric is not reliably detectable or estimable in current NTTP studies.
- Overestimation of pesticide risks may occur when relying on the ER05.
- Further refinement of NTTP testing protocols is needed for accurate risk assessment.
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