Miroslav Machala

Cell bioassays for detection of aryl hydrocarbon (AhR) and estrogen receptor (ER) mediated activity in environmental samples.

In vitro cell bioassays are useful techniques for the determination of receptor-mediated activities in environmental samples containing complex mixtures of contaminants. The cell bioassays determine contamination by pollutants that act through specific modes of action. This article presents strategies for the evaluation of aryl hydrocarbon receptor (hereafter referred as dioxin-like) or estrogen receptor mediated activities of potential endocrine disrupting compounds in complex environmental mixtures. Extracts from various types of environmental or food matrices can be tested by this technique to evaluate their 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents or estrogenic equivalents and to identify contaminated samples that need further investigation using resource-intensive instrumental analyses. Fractionation of sample extracts exhibiting significant activities, and subsequent reanalysis with the bioassays can identify important classes of contaminants that are responsible for the observed activity. Effect-directed chemical analysis is performed only for the active fractions to determine the responsible compounds. Potency-balance estimates of all major compounds contributing to the observed effects can be calculated to determine if all of the activity has been identified, and to assess the potential for interactions such as synergism or antagonism among contaminants present in the complex mixtures. The bioassay approach is an efficient (fast and cost effective) screening system to identify the samples of interest and to provide basic information for further analysis and risk evaluation.

Analysis of polycyclic aromatic hydrocarbons and their nitro‐derivatives in farm road and barn dust

Road and barn dust samples were analysed for polycyclic aromatic hydrocarbons (PAHs) and nitrated polycyclic hydrocarbons (nitro‐PAHs). For this purpose, suitability of optimised HPLC with fluorimetric detection and GC/MS, both preceded by Soxhlet extraction of samples, gel permeation chromatography and HPLC with silica gel column for clean‐up, fractionation and preconcentration of the analytes, were compared. The detection limits of GC/MS for 16 PAHs ranged from 5 to 10 pg. The detection limits of GC/MS for 11 nitro‐PAHs ranged from 20 to 60 pg and those of on‐line reduction HPLC with fluorescence detection from 0.5 to 5 pg. Therefore, procedures with a higher separation efficiency and a more selective detection, such as GC/MS should be preferred when low concentrations of nitro‐PAHs are expected. PAH concentrations in road dust and barn dust samples ranged from 527 to 5680 μg/kg, and from 114 to 740 μg/kg, respectively. Nitro‐PAHs were detected in one sample of barn dust and two samples of road dust. Th...

Project Idris — Ecological Risk Assessment — Regional Approaches

Ecological risk assessment (EcoRA) is a rapidly evolving discipline that is quickly being incorporated into the daily routines of industry and government. The conceptual design is based on the development of expert system (SETAC Workshop, Breckenridge, Co, 1987) and decision-support system (ERADSS - Pelston Workshop, Mi, 1994). Ecological risk assessment frameworks have recently been completed or are under development in numerous countries of Europe, the US, and Canada. Presently, many specific approaches and models exist in numerous sub-disciplines of EcoRA, such as chemical-property and fate estimation, toxicity, biological uptake, and population effects with limited co-ordination across these sub-disciplines. The ecological risk assessment framework shows’ the trends of global harmonization of EcoRA and development of common methods, data and criteria and pooled resources to obtain more cost-effective, consistent, and flexible systems with reduced duplication of effort and incompatibilities.