Extracts from settling particulate matter collected in the Stockholm archipelago waters: Embryolethality, immunotoxicity and erod‐inducing potency of fractions containing aliphatics/monoaromatics, diaromatics or polyaromatics

Bioassays previously used for evaluating the toxic potency of specific compounds as well as mixtures proved useful for testing extracts of environmental samples. Samples of settling seston, that is, settling particulate matter in water, were collected with sediment traps placed in the Stockholm archipelago. The samples were Soxhlet extracted with toluene, the extracts run through an Si column, and the eluates separated by HPLC into (a) aliphatics and monoaromatics, (b) diaromatics (e.g., polychlorinated dibenzo-p-dioxins [PCDDs] and dibenzofurans [PCDFs] and polychlorinated biphenyls [PCBs]), and (c) polyaromatics. Toxic potency was evaluated in terms of mortality in chick embryos, induction of 7-ethoxyresorufin-O-deethylase (EROD) in chick embryos, inhibition of lymphoid development in chick embryo bursae, and inhibition of lymphoid development in mouse thymus anlagen in vitro. The polyaromatic fraction from seston collected at a location (inner archipelago) close to the center of Stockholm was the most potent of the tested fractions. The polyaromatic fractions were analyzed to determine their contents of 15 polycyclic aromatic hydrocarbons (PAHs) that had previously been toxicity tested. The concentrations of these PAHs were too low to explain the toxicities of the polyaromatic fractions. The diaromatic fraction from the inner archipelago was about four- to fivefold less potent as an EROD inducer and at inhibiting lymphoid development in mouse thymus anlagen in vitro, compared with the polyaromatic fraction from this location. Analysis of PCDD/Fs and three coplanar PCBs in this diaromatic fraction revealed that these compounds were responsible only for a minor part of the toxicity of the fraction.