Acute toxicity and genotoxicity of aquatic hydrophobic pollutants sampled with semipermeable membrane devices.

Triolein-filled semipermeable membrane devices (SPMDs) were deployed for 4 weeks in polluted water sources in Lithuania. The mixtures of pollutants sampled by the SPMDs were fractionated by size-exclusion chromatography (SEC). The fraction containing average molecular weight compounds such as polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides was screened by gas chromatography and mass spectrometry. The whole (non-fractionated) samples and their SEC fractions were tested in bioassays including Microtox, Mutatox, Daphnia pulex immobilization assay and the sister chromatid exchange (SCE) in human lymphocytes in vitro test. The Microtox test was most sensitive with the estimated EC(50) values in the range of milligrams or even micrograms per milliliter based on the amount of the SPMD triolein. Part of the observed toxicity was caused by elemental sulfur co-sampled by the SPMDs from sediments. The sum of toxicity equivalents of the SEC fractions was smaller than the relative toxicity of the whole samples indicating the presence of synergistic interactions in the complex mixtures of chemical pollutants. The toxic or genotoxic response induced by the chemical mixtures and their fractions was smaller in the D. pulex, Mutatox and SCE tests. In Mutatox, a positive response was only detected without the S9 metabolic activation which indicates the presence of mainly direct-acting mutagens in the samples. Interpretation of the Mutatox data was difficult due to the complexity of dose-response and time-response relationships. The study has demonstrated the potential as well as some limitations of SPMDs in the monitoring of biological effects of bioavailable organic pollutants in the aquatic environment.