Overview of Environmental Risk Assessment of Pesticides in China

Environmental risk assessment refers to the use of science, technology and available information to assess the potential risks and adverse effects of pesticide use on the environment under specific conditions. It is an integral part of pesticide registration data requirements in China, particularly for new formulations, new uses and new application methods. At present, protection targets considered in environmental risk assessment in China include aquatic ecosystem, birds, bees, silkworm, groundwater, non-target arthropods and soil organisms. Sediment-dwelling organisms are currently not considered.

Environmental Risk Assessment Guidelines

In China, we need to follow the following technical guidelines when preparing environmental risk assessment report. The principles are largely aligned with EFSA guidelines.

1. NY/T 2882.1-2016 Guidance on environmental risk assessment for pesticide registration –Part 1: General principles

2. NY/T 2882.2-2016 Guidance on environmental risk assessment for pesticide registration –Part 2: Aquatic ecosystem

3. NY/T 2882.3-2016 Guidance on environmental risk assessment for pesticide registration –Part 3: Birds

4. NY/T 2882.4-2016 Guidance on environmental risk assessment for pesticide registration –Part 4: Honeybee

5. NY/T 2882.5-2016 Guidance on environmental risk assessment for pesticide registration –Part 5: Silkworm

6. NY/T 2882.6-2016 Guidance on environmental risk assessment for pesticide registration –Part 6: Groundwater

7. NY/T 2882.7-2016 Guidance on environmental risk assessment for pesticide registration –Part 7: Non-target arthropods

8. NY/T 2882.8-2017 Guidance on environmental risk assessment for pesticide registration –Part 8: Soil organism

Aquatic Ecosystem

There are currently two official models for aquatic exposure assessment: Top-Rice and PSEM (still draft). Top-Rice is only used for rice while PSEM (draft) is for other dryland crops. Input values include e-fate properties and use pattern. Output values include peak predicted environmental concentrations (PECmax) and time-weighted average concentrations (PECtwa) in surface water.

For hazard/effect assessment, we need to consider the ecotoxicity data of vertebrates, invertebrates and primary producer. Vertebrates include fish and amphibians. Invertebrates include crustacean arthropods, aquatic insects, etc., and primary producers include green algae, blue-green algae, diatoms, large aquatic plants, etc. Geometric mean values are used when the same species has multiple toxicity endpoint data. When the toxicity of a formulation is significantly (5-fold) increased or decreased when compared to the toxicity endpoint of the active ingredient, the toxicity endpoint of the formulation shall be used in environmental risk assessment. When calculating PNEC values, a UF of 100 is usually used for acute aquatic risks while a UF of 10 is used for chronic risks.

For risk characterization, when the RQ (=PEC/PNEC) values of 60% of all time scenarios <1, and the RQ of the remaining 40% of time scenarios <10, the risk to the aquatic ecosystem is considered acceptable. This is the pass criterion for rice. The pass criterion for dryland crops has not been released yet.

Please note: major environmental metabolites (>10% AR) shall also be assessed in this part.

Birds

Main pesticide exposure routes to birds include pesticide spraying, seed treatment, granule application and bait. During exposure analysis, it is important to choose right indicator species according to crops/seed size. Acute, short-term and long-term predicted exposure doses (PEDs) are calculated respectively.

For effect/hazard assessment, when there are acute toxicity data of different species, the geometric mean value (LD50) of multi-species toxicity test data should be used to calculate acute and short-term predicted no-effect dose PNEDs (UF=10). When there is reproductive toxicity data of different species, the reproductive toxicity endpoint value (NOED) of the most sensitive species should be used to calculate chronic PNEDs (UF=5).

For risk characterization, when the RQ (=PED/PNED) is greater than 1, the risk of the pesticide to birds is unacceptable (RQ>1). Then appropriate risk mitigation measures should be put on labels such as "Cover soil immediately after application", "prohibited near bird protection zone" and so on.

Bees

Pesticide exposure to bees includes spraying on crops, soil treatment or seed treatment. For the spray scenario, the lowest LD50 of acute oral or contact bee toxicity data of the active ingredient and formulation shall be used. For seed treatment scenario, the endpoint of the acute oral toxicity data of the active ingredient should always be used.

The risk quotient RQ to bee is calculated as follows (UF=50):

RQ=Application Rate/(LD50×50)

When the risk to bees is unacceptable (RQ>1), risk mitigation measures should be taken, such as labeling "It is prohibited to apply this product near flowering plants”.

Silkworms

Main pesticide exposure routes to silkworms include direct spraying and drifting, etc. The risk of pesticides to silkworms is negligible when used indoors in closed structures such as greenhouses, houses, granaries, etc., or for non-spray use such as trunk injection, seed treatment agents and granules (except for systemic pesticides).

Predicted Non-Effect Concentration (PNEC) is calculated using the lowest semi-lethal concentration (LC50) obtained from acute silkworm toxicity test.

When the risk of silkworms is unacceptable, risk mitigation measures should be specified on labels, such as “using the outermost mulberry tree as the isolation belt” or "forbidden near the silkworm room and mulberry garden".

Groundwater

For dryland crops, China-Pearl model is used to calculate predicted environmental concentrations in groundwater (PECgw). For rice, TOP-RICE model should be used.

Predicted Non-Effect Concentration (PNEC) is calculated using ADI and the following equation.

PNEC = ADI x BW x P / C, where

ADI: Acceptable Daily Intake (mg/kg bw)

BW: Body Weight, default 63kg

P: Default 20% of groundwater contributing to ADI

C: Daily water consumption, default 2L

The risk quotient RQ to groundwater is calculated as PEC/PNEC. If RQ>1, the risk of the pesticide to groundwater is unacceptable. There is no acceptable risk mitigation measures.

Non-target arthropods

Main pesticide exposure route to non-target arthropods includes spraying. The risk of pesticides to non-target arthropods is negligible when used in enclosed structures such as greenhouses, houses, granaries, etc., indoors, or for outdoor uses such as trunk injections, seed treatment agents and granules (except for systemic pesticides).

Exposure assessment is divided into in-field exposure and out-field exposure. In the hazard/effect assessment, 1 species of parasitic and predatory NTAs sensitive to pesticides should be selected as the representative species, and when the same type of NTAs has multiple LR50 values, the most sensitive LR50 value should be selected for assessment.

When the risk to non-target arthropods is unacceptable, risk mitigation measures should be specified on labels such as "Prohibited near trichogramma and other natural enemy release areas ".

Soil Organisms

PECsoil_SFO_China (xls) is used to calculate predicted environmental concentrations in soil (PECsoil). Both parents and major soil metabolites shall be evaluated during exposure analysis.

Usually, only acute effect assessment is needed using acute toxicity data of earthworms and soil microorganisms. Chronic effect assessment of soil organisms is required when the acute risk RQ>1 or there is potential cumulative risk of the pesticide in soil, for example, DT50>180 d.

Our Services

CIRS Group can provide high-quality environmental risk assessment for pesticides at affordable price. It can be a preliminary environmental risk assessment to help you identify whether there are any registration risks or a formal full enviromental risk assessment report to support your product registration in China. We also offer advice on refinement strategies should tier 1 environmental risk assessment fails.