Are standard aquatic test species and methods adequate surrogates for use in environmental risk assessment of pesticides in tropical environments?

Abstract

In regulatory risk assessment, surrogate species of fish, aquatic invertebrates, and primary producers are tested to assess toxicity and subsequently the risk of pesticides to freshwater biota. This study evaluates whether the standard, surrogate test species (mostly temperate in latitudinal distribution) used in many parts of the world are suitable surrogates for first-tier risk assessments involving tropical freshwater biota. Data for the toxicity of pesticides to tropical fish, invertebrates, and primary producer species were extracted from the USEPA ECOTOX database and peer-reviewed literature. For each pesticide, the most sensitive regulatory endpoint extracted from the US Environmental Protection Agency (USEPA) and European Food Safety Authority (EFSA) dossiers for freshwater fish, invertebrates, and primary producers was selected. The ratios of the endpoint for tropical species and for the most sensitive regulatory endpoint for the appropriate taxonomic group were determined. A value >1 indicates that the tropical species is less sensitive than the respective standard regulatory species. Tropical fish species were less sensitive than standard fish species in 84% of the comparisons, and in 93.5% of the comparisons, tropical fish were less or similarly sensitive (within a factor of 5). For aquatic invertebrates, 78.1% of the evaluated tropical species were less sensitive than standard species and 93.3% of tropical invertebrates species were less or similarly sensitive. For primary producers, 96% of tropical species were less sensitive than standard test species. Overall, standard species used globally were more sensitive or similarly sensitive compared to tropical species in more than 93% of the cases. In conclusion, the data show that freshwater toxicity data for pesticides from tests using standard test species, tested according to international accepted guidelines, are appropriate for use in first-tier risk assessments for tropical environments.

Toward a tiered regulatory framework for the prospective aquatic effect assessment of pesticides in (Neo)tropical areas

“…It has often been discussed that there is a deficiency in the availability of toxicity data derived for (Neo)tropical species (Niemeyer et al, 2017; Santos et al, 2023; Wang et al, 2019). Although research efforts have increased in the past decade (Figure 1), these have also been centered on a few local species from few (Neo)tropical countries (Figure 2).…”

“…In addition, no consistent conclusion was drawn in these studies regarding the question to what extent and how toxicity data derived for temperate species can be used in tropical effect assessments. For example, several studies concluded that no additional assessment factor is warranted when using temperate toxicity data for effect assessments in other climatic zones (Daam et al, 2008; Hagen & Douglas, 2014; Khatikarn et al, 2018; Santos et al, 2023). Other studies, however, concluded that an additional assessment factor of 2 (Rijk, 2010; Wang et al, 2014), 2.2 to 6.2 (Hobbs, 2006), 4 (Wang & Leung, 2015), 5 (Wang et al, 2019), or even 10 (Kwok et al, 2007) should be applied when extrapolating temperate toxicity data to tropical regions.…”

“…In addition, no consistent conclusion was drawn in these studies regarding the question to what extent and how toxicity data derived for temperate species can be used in tropical effect assessments. For example, several studies concluded that no additional assessment factor is warranted when using temperate toxicity data for effect assessments in other climatic zones (Daam et al, 2008;Hagen & Douglas, 2014;Khatikarn et al, 2018;Santos et al, 2023).…”