The use of the Hazard Quotient approach to assess the potential risk to honeybees (Apis mellifera) posed by pesticide residues detected in bee‐relevant matrices is not appropriate

Abstract

BACKGROUND Pesticide residue data for pollen and nectar are valuable for characterizing realistic exposure of pollinators, e.g. from agricultural crops, flowering margins. Interpretation of residues relies on comparing exposure with toxicity and the Hazard Quotient (HQ) is widely utilized. However, the HQ (threshold of concern 50) was only validated for foliar sprays, based on application rate as a proxy for exposure, not measured residues in bee‐relevant matrices. RESULTS A review of the literature showed a range of HQ approaches and thresholds of concern used to assess non‐foliar applications and residues detected in bee‐relevant matrices, mostly pollen. The use of the HQ thresholds to assess risks associated with residue data or non‐foliar spray application methods is not validated, does not reflect realistic exposure and the conclusions reached differ substantially from current risk assessment approaches. Re‐evaluation of residue data from the first published use of the concentration‐based HQ (2013) and a recent paper (2021) reduced the proportion of pesticides where a conclusion of potential risk was reached from 30 to 7% and 28% to 3–6%, respectively. CONCLUSIONS An understanding of the applicability of the selected risk assessment approach to the available residue data is needed to enable robust conclusions to be drawn on the potential risk to bees. Use of the HQ approach to assess the risk posed by application methods other than foliar sprays or residues in nectar and pollen is likely to result in unreliable conclusions. An alternative approach should be used to assess the significance of measured residues.

Honey Bee (Apis mellifera) Exposure to Pesticide Residues in Nectar and Pollen in Urban and Suburban Environments from Four Regions of the United States

“…Generating an acute HQ or RQ without considering exposure frequency, route, or time‐cumulative effects does not capture chronic and sublethal effects at the colony level, a concern that has been expressed previously (Aupinel et al, 2007; Thompson & Thorbahn, 2009). Indeed, there has been growing support for chronic, rather than acute, risk assessments of pollinator exposure to pesticides (EFSA, 2014; Halm et al, 2006; Hesketh et al, 2016; Mommaerts et al, 2010; Simon‐Delso et al, 2018; Spurgeon et al, 2016).…”

Quantifying exposure of bumblebee (Bombus spp.) queens to pesticide residues when hibernating in agricultural soils

“…For instance, the maximum residue concentration found for cyantraniliprole (148 ng/g) represents an exposure to 15.8% of the honeybee contact LD50 (934 ng/g) for this AI, close to the 20% threshold set by EFSA (2013) for acute contact exposure level of concern. However, this calculation is imperfect considering that contact transfer factors from soil residues are currently unknown (Thompson 2021). Oral exposure may also be of concern, considering that bumblebee queens use their mandibles to dig into the ground (Alford 1969) and exposure to 148 ng/g of cyantraniliprole represents 13.5% of the honeybee oral LD50 (1,100 ng/g), exceeding the 3% EFSA (2013) level of concern for chronic oral exposure.…”

Risk Classification Study of Carbofuran in Vegetables Based on K-Means++ Algorithm

“…This system uses the risk quotient (HQ) to evaluate the health risk of carbofuran in vegetables [4]. An indicator value greater than 1 indicates that there is some risk, and the greater the HQ value, the greater the risk; an indicator value less than 1 indicates that there is no risk, and the smaller the HQ value, the lower the risk level.The model is expressed as:…”