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Dose response OECD 216 studies for agrochemicals.
Christopher J Sweeney1, Melanie Bottoms1, Kerry Hutcheson1
1Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire, UK.
Integrated Environmental Assessment and Management
|April 4, 2026
Summary
The study found that dose response Organisation for Economic Co-operation and Development (OECD) test guideline 216 studies are feasible for agrochemicals, improving European soil microbial risk assessments by focusing on inhibitory effects.
Area of Science:
- Environmental Science
- Ecotoxicology
- Microbiology
Background:
- The Organisation for Economic Co-operation and Development (OECD) test guideline 216 is crucial for European pesticide risk assessment of soil microbiomes.
- Current assessments use a threshold approach, but dose response designs are proposed for agrochemicals.
Purpose of the Study:
- To explore the appropriate performance and interpretation of dose response OECD 216 studies for agrochemicals.
- To compare endpoint calculation methods and assess the impact of study length and response interpretation.
Main Methods:
- Conducted dose response OECD 216 nitrogen transformation tests on four agrochemicals.
- Compared four methods for endpoint calculation.
- Evaluated study length and the interpretation of stimulatory versus inhibitory responses.
Main Results:
- Endpoint calculation method had minimal impact on ecotoxicological inference.
- Hormetic responses observed in two compounds, indicating the system did not reach steady state within 28 days.
- Test extensions beyond 28 days may be necessary.
Conclusions:
- Dose response OECD 216 studies are viable for agrochemicals.
- Focusing on inhibitory responses in dose response studies is recommended.
- These studies offer a more refined approach to European soil microbial risk assessment.
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