Ratios between acute aquatic toxicity and effects on population growth rates in relation to toxicant mode of action

Abstract

Environmental risk assessment of chemicals is mostly based on the results of standardized toxicity tests. To obtain environmental quality criteria, extrapolation factors are used that depend on the amount and quality of available data. These extrapolation factors do not, however, take into account the mode of action of the compound tested or the life history of the test organism. In this study, we analyzed the variability in acute‐to‐chronic ratios (ACRs) for various chemicals in relation to their mode of action. Chemicals were classified as nonpolar narcotics, polar narcotics, specifically acting compounds, and heavy metals. As an acute endpoint, the LC50 was used; as a chronic endpoint, the lowest test concentration at which the natural rate of population increase (r) is affected, or LOEC(r), was used. Data were derived from the on‐line literature. Nonpolar narcotic chemicals demonstrate the smallest variation in ACRs, and acute tests can be used to derive chronic endpoints for this class. For the other classes, the variation in ACRs is larger. Fish species especially show a relatively large ACR. For heavy metals, differences in the mode of action may play an important role in explaining differences in ACRs. For the other three classes, however, it is less reliable to predict chronic toxicity using the results of acute tests. In general, differences in species sensitivity rather than in mode of action for the chemical seem to determine differences in ACRs.

Response spectrum of fluoranthene and pentachlorobenzene for the fathead minnow (Pimephales promelas)

“…Previous studies have determined that ACRs for nonpolar narcotic compounds range from 2.58 to 5.09 [18,44,45]. Our data also suggest that this may be the case.…”

Prediction of Ecological No-Effect Concentrations for Initial Risk Assessment: Combining Substance-Specific Data and Database Information

“…An indication in this direction was obtained by Roex et al [26], who found a significantly lower AF acute-chronic for narcotic substances than for substances with a specific mode of action. An indication in this direction was obtained by Roex et al [26], who found a significantly lower AF acute-chronic for narcotic substances than for substances with a specific mode of action.…”

“…An indication in this direction was obtained by Roex et al [26], who found a significantly lower AF acute-chronic for narcotic substances than for substances with a specific mode of action. A possible explanation for these contrary findings is the fact that Roex et al [26] used chronic toxicity data on population growth only, whereas our database includes numerous toxic endpoints. A possible explanation for these contrary findings is the fact that Roex et al [26] used chronic toxicity data on population growth only, whereas our database includes numerous toxic endpoints.…”

Effects of an anionic surfactant (FFD-6) on the energy and information flow between a primary producer (Scenedesmus obliquus) and a consumer (Daphnia magna)

“…This fits in a consistent pattern as for several other toxicants, such as metals and pesticides, EC 50 values for feeding inhibition were 5–130 times lower than LC 50 values (Gliwicz and Sieniawska 1986; Hartgers et al 1999; McWilliam and Baird 2002). Since acute studies might provide a good indication of population level effects using an extrapolation factor of 10 between the LC 50 and the NOEC (Roex et al 2000), extrapolation would yield a chronic Daphnia population level NOEC of 2.6 μl FFD-6 l −1 , which is about 1.5 mg FFD-6 l −1 . Such chronic NOEC value would be lower than the EC 50 value for feeding inhibition, but in good agreement with reported NOEC values for chronic exposure of Daphnia to anionic surfactants (Lewis 1991).…”