Revised guidance on the risk assessment of plant protection products on bees (Apis mellifera, Bombus spp. and solitary bees)

Abstract

The European Commission asked EFSA to revise the risk assessment for honey bees, bumble bees and solitary bees. This guidance document describes how to perform risk assessment for bees from plant protection products, in accordance with Regulation (EU) 1107/2009. It is a review of EFSA's existing guidance document, which was published in 2013. The guidance document outlines a tiered approach for exposure estimation in different scenarios and tiers. It includes hazard characterisation and provides risk assessment methodology covering dietary and contact exposure. The document also provides recommendations for higher tier studies, risk from metabolites and plant protection products as mixture.

Keywords: bees; higher tier studies; pesticides; risk assessment.

Figure 1

Bee exposure pathways evaluated in this guidance document and possible effects in time. It is noted that exposure via contaminated matrices other than pollen and nectar or exposure via inhalation are not included in the figure, since this was not specifically evaluated in this guidance

Figure 2

Tiered approach and explanations what each exposure or effect‐tier implies for the risk assessment of active substance. According to the principle of the tiered approach, each exposure‐tier can be linked to each effect‐tier

Figure 3

Overview of the lower tier risk assessment process for the active substance for honey bees (HB). Risk assessment of metabolites covered in Chapter 11. Risk assessment of mixture covered in Chapter 12. TRT = time reinforced toxicity (for honey bees). PEQj = predicted exposure quantity for the four risk cases (indicated by the suffix j) i.e. acute‐contact, acute‐dietary, chronic‐dietary, larvae‐dietary. Risk mitigation measures could be considered in the problem formulation to quantify the exposure reduction. Modelling could be considered as part of the higher tier assessment

Figure 4

Overview of the higher tier risk assessment scheme for honey bees (for further details, see Chapter 10 and Annex C). EEDj = Estimated Exposure Dose for the four risk cases (indicated by the suffix j) i.e. acute‐contact, acute‐dietary, chronic‐dietary, larvae‐dietary

Figure 5

Elements of the GAP and physico‐chemical properties/behaviour of the compound in the environmental matrices determine the exposure scenarios, the route of the exposure and the bee exposure estimation to PPPs

Figure 6

(A) Field margin A scenario for contact route of exposure for all bee groups and for the dietary exposure for bumble bees and solitary bees; (B) – field margin B scenario for the dietary exposure for the honey bees; (C) – adjacent crop scenario for the dietary exposure for honey bees (TC = treated crop; FM = field margin; AC = adjacent crop)

Figure 7

Visual interpretation of PEQdi derivation for Tier 1 and for Tier 2 exposure assessment

Figure 8

examples of different situations concerning the time course of effects. In panel A, full expression of effects depends on the exposure time. Uncertainty ranges of the LDD50 at 2 and 10 days are well separated (red dotted lines show lower limit of LDD50 at 2 days and upper limit at 10 days). In panel B, effects are almost entirely expressed after a short time. Uncertainty ranges of the LDD50 at day 1 and day 10 overlap. In such cases, the assumptions normally used for estimating chronic exposure are not appropriate

Figure 9

Flowchart illustrating the Step 1 of the process underpinning the selection of the hazard parameters for the risk assessment of honey bees. In this picture, tests are considered equivalent when they relate to the same risk case

Figure 10

Flowchart illustrating the Step 2 of the process underpinning the selection of the hazard parameters for the risk assessment of honey bees. Note that the comparison of the LD50_j between active substance and PPP entails additional consideration in case of surrogate DRC_j (see text)

Figure 11

Flowchart illustrating the Step 3 of the process underpinning the selection of the hazard parameters for the risk assessment of honey bees

Figure 12

Flowchart illustrating the Step 4 of the process underpinning the selection of the hazard parameters for the risk assessment of honey bees. The effect of the exposure length is considered minor if the LDD50 after 2 days and after 10 days are not significantly different and present a ratio < 3

Figure 13

Graphical illustration of the proposed calculation for the effect on a specific endpoint using a non‐linear dose–response curve (DRC_j). The resulting mortality (%) can be interpreted as probability of one individual to die on exposure to a certain dose, which can also be interpreted as a percentage of a cohort of individual bees to die after exposure to the identical dose

Figure 14

Combined risk assessment in relation to the exposure‐tier

Figure 15

Flowchart of the scheme for the assessment whether a substance exhibits time‐reinforced toxicity

1. 1: Lifespan dose–response is calculated using the selected GUTS model, for both the active period and winter scenario.
2: This part has to be duplicated for the active period and the winter (inactive) period.
3: When an effect > 10% is predicted, either higher tier studies can be performed, or a specific TRT laboratory study can be executed. This second option is only applicable when this conclusion of > 10% effect is reached on the basis of the worst‐case assumption that Haber's exponent = −2.

Figure 16

Assessment strategy for sublethal effects

Figure 17

Boxplot showing the proportion of abnormal behaviour across a range of PPP concentrations aggregated across the entire experiment, note that the y axis is truncated at 0.2

Figure 18

Exposure regime in higher tier effect studies should be estimated and compared with the PEQ in order to assess the plausibility of the biological observations in the studies. The suffix ‘j’ indicates the 4 risk cases (acute contact, acute, dietary, chronic, larvae). *The EEDcontact in semi‐field studies, does not require to be estimated since the exposure level in the study is confirmed by the flight activity as described in Annex C of this guidance document

Figure 19

Summary of the WoE + uncertainty analysis process

Figure 20

Flowchart for metabolite risk assessment

Figure 21

Illustration for a 1:1 mixture of substance A and substance B. Both DRCs of the substances are described by log‐logistic models, with the same LD50 of 10 (generic unit). The (red) curve describing the mixture is closer to Substance A in the left part of the plot, and then closer to Substance B in the right part. This is because the difference in the slope makes substance A the driver of the effects at lower doses and substance B the driver at higher doses. Despite the fact that the DRC of each component is described by a log‐logistic model, the asymmetry of the resulting curve makes it unsuitable to be described by the same model

Figure 22

Workflow illustrating the risk assessment scheme for mixtures. *LD_{50,j,mix‐DA} may need to be corrected by an appropriate Model Deviation Ratio (MDR) from other risk cases/species when synergism is plausible (see text in steps 5–6)