Biomarkers and bioassays as alternative screening methods for the presence and effects of PCDD, PCDF and PCB

Toxicity evaluation by using intact sediments and sediment extracts

The toxicity of intact sediments and sediment extracts, from both an uncontaminated site and a site contaminated by pulp-mill effluents, was tested in a five months study. The deposit-feeding amphipod Monoporeia affinis was exposed in soft-bottom flow-through water microcosms. To examine potential toxicity a set of reproduction endpoints was used including fecundity and different embryo aberrations such as malformed eggs. Among extracts, the aliphatic/monoaromatic and diaromatic fractions along with the total extract were shown to cause the highest toxicity measured as malformed eggs, while the polyaromatic fraction caused toxicity at background levels. A comparison between sediment extracts and pulp mill contaminated intact sediment, however, showed no toxicity of the intact sediment. Thus, the extraction procedure seems to increase bioavailability and subsequently toxicity as compared to the intact sediments in situ. In toxicity testing using fractionated extracts of sediments in a toxicity identification evaluation (TIE) procedures, caution should therefore be taken when assessing bioavailable contaminants in contaminated areas. This should be taken in account both in determining remediation priorities as well as in ecological risk assessments.

Bioanalytical screening methods for dioxins and dioxin-like compounds a review of bioassay/biomarker technology

Determination of environmental pollutants utilizing biodetectors such as bioassays, biomarkers, enzyme immunoassays (EIAs), or other bioanalytical tools is a continuously growing area. The present literature review describes the principles and advantages/limitations of several bioanalytical detection methods (BDMs) for the screening and diagnosis of dioxin and dioxin-like compounds. This study characterizes briefly the family of dioxin and dioxin-like compounds, discusses potential Ah receptor (AhR) ligands and cytochrome P-450 (CYP) 1A1-enzyme-inducing compounds. 'Milestones' in the development of BDMs are summarized and explained in detail for a number of bioanalytical tools that can be used to detect these classes of dioxin-like persistent bioaccumulative toxicants (PBTs). The design of a screening profile with a battery of bioassays/biomarkers coupled with the chemical analysis is evaluated. The relative potencies (REPs) to 2,3,7,8-TCDD for dioxin-like compounds are reviewed for various BDMs and the differences are noted.

Optimisation and use of tandem-in-time mass spectrometry in comparison with immunoassay and HRGC/HRMS for PCDD/F screening

Rapid screening of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans using quadrupole ion storage tandem-in-time mass spectrometry (QISTMS) conjointly with polyclonal antibody immunoassay has been considered. The optimisation of the fragmentation of the parent ion in the trap has been completed. The analysis of fly ashes from a municipal waste incinerator contaminated at different levels has then been realised. Results obtained using QISTMS, HRMS and immunoassay are compared.

Establishment of a simple cleanup procedure and bioassay for determining 2,3,7,8-tetrachlorodibenzo-p-dioxin toxicity equivalents of environmental samples

The study was aimed at establishing a bioassay for the determination of 2,3,7,8-tetrachlorodibenzo-p-dioxin toxicity equivalents (TEQs) in environmental samples. Specifically, development of a rapid cleanup procedure adapted to the needs of the bioassay and simplification of the measurement of its endpoint, the induction of 7-ethoxyresorufin O-deethylase (EROD) in rat H4IIEC3/T hepatoma cells, were desired. The results indicate that a single "sandwich" column suffices to remove substances that may interfere with the bioassay from extracts of various environmental matrices such as sewage sludge, compost, soil, sediment, fly ash, tissue filter dust, and fire residue. The cumbersome conventional in vitro assay for EROD activity on cells exposed to the test material in culture plates could readily be replaced by a simple assay on intact cells grown and treated in 96-well microtiter plates. TEQ values obtained from the bioassays were consistently higher than those derived from chemical analysis of dibenzo-p-dioxins/furans and biphenyls by a factor of 1.5-3.0 depending on the matrix used. The results indicate that this bioassay, which combines a simple cleanup and a rapid procedure for measuring biological effects, offers a cost- and time-effective alternative to chemical analysis when screening large numbers of samples from complex environmental matrices.

Individual PCBs as predictors for concentrations of non and mono-ortho PCBs in human milk

32 Dutch human milk samples were analyzed for PCBs with either HRGC-ECD or HRGC-LRMS in the NCI mode. Samples were collected from three different locations in The Netherlands: Amsterdam, Rotterdam and Groningen. Quantitatively, no differences could be observed between the three localities, while in addition the congener specific pattern showed a striking similarity for all individual samples. Only principal component analysis revealed slight individual differences. Based on similarities in the PCB profiles, linear relationships were calculated between 2,3'4,4',5-PnCB (#118) or 2,2'4,4'5,5'HxCB (#153) and the most relevantnon andmonoortho PCBs exhibiting dioxinlike activity. These PCBs included 2,3,3',4,4'-PnCB (#105), 3,3',4,4'5-PnCB (#126) 2,3,3',4,4',5-HxCB (#156), 2,3,3',4,4',5'-HxCB (#157), 2,3',4,4',5,5'-HxCB (#167) and 3,3',4,4',5'5-HxCB (#169).Good linear relationships were observed between individual PCBs. Based on the results of this study, PCB #118 can be used to predict concentrations of the PCBs #105 and #126. PCB #153 can be used as a predictor for the PCBs #156, #157, #167 and #169, but also for the total toxic equivalencies (TEQs) ofnon andmonoortho PCBs present in human milk. This method using certain PCBs as predictors for other toxicological relevant congeners, can be useful and cost effective, e.g. for epidemiological studies. However, before applied a number of conditions should be met. These are: 1) A stable composition of the PCB matrix should be established. 2) A possible time dependent change in composition of the matrix should first be excluded when used over different time periods.