How to Characterize Chemical Exposure to Predict Ecologic Effects on Aquatic Communities?

Abstract

Reliable characterization of exposure is indispensable for ecological risk assessment of chemicals. To deal with mixtures, several approaches have been developed, but their relevance for predicting ecological effects on communities in the field has not been elucidated. In the present study, we compared nine metrics designed for estimating the total toxicity of mixtures regarding their relationship with an effect metric for stream macroinvertebrates. This was done using monitoring data of biota and organic chemicals, mainly pesticides, from five studies comprising 102 streams in several regions of Europe and South-East Australia. Mixtures of less than 10 pesticides per water sample were most common for concurrent exposure. Exposure metrics based on the 5% fraction of a species sensitivity distribution performed best, closely followed by metrics based on the most sensitive species and Daphnia magna as benchmark. Considering only the compound with the highest toxicity and ignoring mixture toxicity was sufficient to estimate toxicity in predominantly agricultural regions with pesticide exposure. The multisubstance Potentially Affected Fraction (msPAF) that combines concentration and response addition was advantageous in the study where further organic toxicants occurred. We give recommendations on exposure metric selection depending on data availability and the involved compounds.

Using phylogenetic information and chemical properties to predict species tolerances to pesticides

“…B 281: 20133239 while others remain [27]. Moreover, the predictions might support mixture toxicity models that usually suffer from a low number of test data for each compound [28].…”

Sources, occurrence and predicted aquatic impact of legacy and contemporary pesticides in streams

“…25 sub-samples collected in depositional areas to meet minimum analytical 186 requirements for sample mass. Further details of the study catchments, sampling methods and pesticide 187 screening are provided elsewhere (McKnight et al, 2012;Rasmussen et al, 2013). Analysis of water 188 8 samples for non-polar compounds were conducted using liquid-liquid extraction followed by 189 quantification on GC-MS. Polar compounds were solid-phase extracted and quantified by liquid 190 chromatography tandem mass spectrometry (LC-MS/MS), as described in Jansson and Krueger (2010).…”

“…Pesticides are now widely recognized as prevalent (Konstantinou et 47 6 the catchment land use (Rasmussen et al, 2013). One stream is located in the Skensved catchment (Fig.…”

Organic chemicals jeopardize the health of freshwater ecosystems on the continental scale

“…These safety factors are supposed to protect the nontarget species from the likely effects of chemicals. More sophisticated approaches such as species sensitivity distributions (SSDs), which allow for derivation of thresholds that are assumed to protect a distinct percentage of species (usually 95%), are generally not applicable for datasets with a high number of chemicals, due to a paucity of toxicity data (15). However, establishing effect thresholds that are protective for the entire ecosystem is an ongoing challenge, due to difficulties with addressing the inherent differences between laboratory test systems and field situations and due to the required balance of ecosystem protection and economic development (13).…”