Dietary Toxicity Thresholds and Ecological Risks for Birds and Mammals Based on Species Sensitivity Distributions

Abstract

Species sensitivity distributions (SSDs) are commonly used in regulatory procedures and ecological risk assessments. Yet, most toxicity threshold and risk assessment studies are based on invertebrates and fish. In the present study, no observed effect concentrations (NOECs) specific to birds and mammals were used to derive SSDs and corresponding hazardous concentrations for 5% of the species (HC5 values). This was done for 41 individual substances as well as for subsets of substances aggregated based on their toxic Mode of Action (MoA). In addition, potential differences in SSD parameters (mean and standard deviation) were investigated in relation to MoA and end point (growth, reproduction, and survival). The means of neurotoxic and respirotoxic compounds were significantly lower than those of narcotics, whereas no differences were found between end points. The standard deviations of the SSDs were similar across MoA's and end points. Finally, the SSDs obtained were used in a case study by calculating Ecological Risks (ER) and multisubstance Potentially Affected Fractions of species (msPAF) based on 19 chemicals in 10 Northwestern European estuaries and coastal areas. The assessment showed that the risks were all below 2.6 × 10. However, the calculated risks underestimate the actual risks of chemicals in these areas because the potential impacts of substances that were not measured in the field or for which no SSD was available were not included in the risk assessment. The SSDs obtained can be used in regulatory procedures and for assessing the impacts of contaminants on birds and mammals from fish contaminants monitoring programs.

Applying adverse outcome pathways and species sensitivity–weighted distribution to predicted‐no‐effect concentration derivation and quantitative ecological risk assessment for bisphenol A and 4‐nonylphenol in aquatic environments: A case study on Tianjin City, China

“…Thus, specific endpoints/biomarkers measured by toxicologists are significant factors that affect the sensitivity of species. In several studies, both biochemical or molecular responses [8,46,47] and mode of action-related endpoints [48][49][50][51] were emphasized, especially for EDCs, in PNEC derivation and ecological risk assessment.…”

Deriving Field-Based Ecological Risks for Bird Species

“…The ecological risk (ER; fraction) is defined as the probability of a species in a certain area exceeding its EC 10 or EC 50 and represents the overlap between the derived SSD and the exposure concentration distribution (ECD) of a certain chemical in a specific area (as exemplified in Figure 1 ). ERs are calculated through integral 6 , 7 where PDF ECD is defined as the probability density function of the natural log-transformed exposure concentration distribution of an individual chemical found in bird’s eggs in a specific area. CDF SSD is the (cumulative) single substance SSD model based on field-based EC 10 s and EC 50 s.…”

“…ERs based on SSDs derived for respectively EC 10 s and EC 50 s for single toxicant exposure were calculated based on Korsman et al 2016 7 in R statistics 3.3.1 using in which the function pnorm returns a probability distribution function and where μ SSD is the natural log-transformed mean of the SSD and σ SSD reflects the natural log-transformed standard deviation of the SSD. The μ ECD and σ ECD are the mean and standard deviation associated with the natural log-transformed contaminant concentrations found in bird’s eggs in a certain area.…”

“… 6 ERs are defined as the probability of measured environmental concentrations exceeding (no) effect concentrations of species. 6 , 7 Effect concentrations, such as half maximal effective concentrations (EC 50 s) or no-observed-effect concentrations (NOECs), are typically obtained from lab experiments. In these experiments, individual performance (e.g., fecundity or mortality) is measured in a controlled setting.…”

“… 9 , 11 , 12 Ecotoxicological data is lacking for many bird species at higher trophic levels (e.g., piscivores, raptors, and insectivores), as laboratory experimentation is limited due to practical, financial, and ethical constraints 13 or focus on acute lethal toxicity only. 7 …”