Acute to chronic ratios in aquatic toxicity—variation across trophic levels and relationship with chemical structure

Abstract

For fish, daphnids, and algae, acute to chronic ratios (ACRs) have been determined from experimental data regarding new and existing chemicals. Only test results in accord with the European Union Technical Guidance Document (TGD) and validated by authorities were considered. Whereas the median ACRs of 10.5 (fish), 7.0 (daphnids), and 5.4 (algae) are well below the ACR safety factor of 100 as implied by the TGD, individual ACRs vary considerably and go up to 4400. The results suggest that a safety factor of 100 is not protective for all chemicals and trophic levels. Neither a correlation between ACR and baseline toxicity as modeled through the logarithmic octanol-water partition coefficient nor an ACR correlation across trophic levels exists. Narcosis is associated with a preference for a low ACR; nevertheless, low ACRs are frequently obtained for nonnarcotics. Analysis of chemical structures led to the derivation of structural alerts to identify compounds with a significantly increased potential for a high ACR, which may prove to be useful in setting test priorities. At present, however, life-cycle tests are the only way to conservatively predict long-term toxicity.

Ecotoxicological risk assessment of chemical pollution in four Iberian river basins and its relationship with the aquatic macroinvertebrate community status

“…Due to the absence of studies relating pollution and long term effects in communities, chronic risk thresholds for algae and fish were based on acute to chronic ratio (Malaj et al, 2014). For algae the acute to chronic factor 5 was used and for fish factor 10 ( Ahlers et al, 2006;Heger et al, 1995;Länge et al, 1998).…”

Assessing the potential exposure risk and control for airborne titanium dioxide and carbon black nanoparticles in the workplace

“…Furthermore, the P(E|D) of TiO 2 -NPs for pulmonary inflammation was then derived by the overall UF of 10,000 (10 for animal-to-human extrapolation, 10 for human variability, 100 for acute-to-chronic extrapolation; USEPA 1995). The P(E|D)of CB-NPs for pulmonary inflammation was then derived by the overall UF of 1,000 (10 for animalto-human extrapolation, 10 for human variability, 10 for subchronic-to-chronic extrapolation; Ahlers et al 2006). Due to uncertainty within a particular dataset, such as that related to exposure analysis of number concentration and dose-response function, equation variables were defined in terms of a probability density function (PDF) derived from a limited number of observations.…”

Integrated testing and intelligent assessment—new challenges under REACH

“…Under chronic conditions, substances might show very specific modes of action with considerably higher toxicity. Different modes of action under acute and chronic conditions may be the main reason for the observation that the acute/chronic ratios for substances tested with the same species cover a range of more than four orders of magnitude (Ahlers et al 2006). Thus, extrapolations from acute to chronic toxicity should only be performed if it is clear that the same mode of action is involved in both situations.…”