Insecticide species sensitivity distributions: Importance of test species selection and relevance to aquatic ecosystems

Abstract

Single-species acute toxicity data and (micro)mesocosm data were collated for 16 insecticides. These data were used to investigate the importance of test-species selection in constructing species sensitivity distributions (SSDs) and the ability of estimated hazardous concentrations (HCs) to protect freshwater aquatic ecosystems. A log-normal model was fitted to a minimum of six data points, and the resulting distribution was used to estimate lower (95% confidence), median (50% confidence), and upper (5% confidence) 5% HC (HC5) values. Species sensitivity distributions for specific taxonomic groups (vertebrates, arthropods, nonarthropod invertebrates), habitats (saltwater, freshwater, lentic, lotic), and geographical regions (Palaearctic, Nearctic, temperate, tropical) were compared. The taxonomic composition of the species assemblage used to construct the SSD does have a significant influence on the assessment of hazard, but the habitat and geographical distribution of the species do not. Moreover, SSDs constructed using species recommended in test guidelines did not differ significantly from those constructed using nonrecommended species. Hazardous concentrations estimated using laboratory-derived acute toxicity data for freshwater arthropods (i.e., the most sensitive taxonomic group) were compared to the response of freshwater ecosystems exposed to insecticides. The sensitivity distributions of freshwater arthropods were similar for both field and laboratory exposure, and the lower HC5 (95% protection with 95% confidence) estimate was protective of adverse ecological effects in freshwater ecosystems. The corresponding median HC5 (95% protection level with 50% confidence) was generally protective of single applications of insecticide but not of continuous or multiple applications. In the latter cases, a safety factor of at least five should be applied to the median HC5.

The relative sensitivity of macrophyte and algal species to herbicides and fungicides: An analysis using species sensitivity distributions

“…The use of SSDs has been widely discussed in the field of ecotoxicology (Posthuma et al 2002) and has been recommended for regulatory assessment of pesticides (Campbell et al 1999;Maltby et al 2005Maltby et al , 2009Van den Brink et al 2006;Brock et al 2011). In the analysis reported here, SSDs were used to address the issue of sensitivity of standard macrophyte and algal test species relative to other macrophyte species.…”

“…In the past, HCx values for insecticides (Maltby et al 2005), herbicides (Van den Brink et al 2006), and fungicides (Maltby et al 2009) have been validated by comparison with the threshold levels resulting from mesocosm studies. For the construction of macrophyte SSDs, the AMRAP guidance document (Maltby et al 2010) recommends that a range of morphologically and taxonomically different macrophyte species should be included.…”

Environmental risk assessment of pesticides in Ethiopia : a case of surface water systems

“…SSDs were calculated and HC5 concentrations determined using data from the US-EPA database (www.epa.gov/ecotox). Using the ETX 2.0.software (Van Vlaardingen et al 2003) to calculate the HC5, data was selected as discussed by Maltby et al (2005). In the second tier the HC5 values were used as NEC values .…”

“…Data from the US-EPA database (www.epa.gov/ecotox) were included and the ETX 2.0. software (Van Vlaardingen et al 2003) was used to calculate the HC5s. Data was selected as discussed by Maltby et al (2005). The calculated HC5s were used as NEC values .…”

“…Kwok et al, 2007;Rico et al, 2010). Gathering sensitivity data for local species enables further examination of whether European and North American data can be extrapolated to other geographical areas (Hose and Van den Brink 2004;Maltby et al, 2005). Although Ethiopia is located in the tropical region, the risk assessment for pesticide registration is solely dependent on the available temperate acute toxicity data .…”