Previous studies of uptake and effects of nanoplastics by marine organisms have been conducted at what may be unrealistically high concentrations. This is a consequence of the analytical challenges in tracking plastic particles in organisms at environmentally relevant concentrations and highlights the need for new approaches. Here, we present pulse exposures of 14C-radiolabeled nanopolystyrene to a commercially important mollusk, Pecten maximus, at what have been predicted to be environmentally relevant concentrations (<15 μg L–1). Uptake was rapid and was greater for 24 nm than for 250 nm particles. After 6 h, autoradiography showed accumulation of 250 nm nanoplastics in the intestine, while 24 nm particles were dispersed throughout the whole-body, possibly indicating some translocation across epithelial membranes. However, depuration was also relatively rapid for both sizes; 24 nm particles were no longer detectable after 14 days, although some 250 nm particles were still detectable after 48 days. Particle size thus apparently influenced the biokinetics and suggests a need for chronic exposure studies. Modeling extrapolations indicated that it could take 300 days of continued environmental exposure for uptake to reach equilibrium in scallop body tissues although the concentrations would still below 2.7 mg g–1. Comparison with previous work in which scallops were exposed to nonplastic (silver) nanomaterials of similar size (20 nm), suggests that nanoparticle composition may also influence the uptake tissue distributions somewhat.

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SUMMARY Alarm substance is a chemical signal released from fish skin epithelial cells after a predator causes skin damage. When other prey fish detect alarm substance by olfaction, they perform stereotypical predator-avoidance behaviours to decrease predation risk. The objective of this study was to explore the effect of sublethal cadmium (Cd) exposure on the behavioural and physiological responses of juvenile rainbow trout (Oncorhynchus mykiss) to alarm substance. Waterborne exposure to 2 μg Cd l–1 for 7 days eliminated normal antipredator behaviours exhibited in response to alarm substance, whereas exposures of shorter duration or lower concentration had no effect on normal behaviour. Furthermore, dietary exposure to 3 μg Cd g–1 in the food for 7 days, which produced the same whole-body Cd accumulation as waterborne exposure to 2 μg l–1, did not alter normal behaviour,indicating that an effect specific to waterborne exposure alone (i.e. Cd accumulation in the olfactory system) results in behavioural alteration. Whole-body phosphor screen autoradiography of fish exposed to 109Cd demonstrated that Cd deposition in the olfactory system (rosette, nerve and bulb) during waterborne exposure was greater than in all other organs of accumulation except the gill. However, Cd could not be detected in the brain. A short-term elevation in plasma cortisol occurred in response to alarm substance under control conditions. Cd exposures of 2 μg l–1 waterborne and 3 μg g–1 dietary for 7 days both inhibited this plasma cortisol elevation but did not alter baseline cortisol levels. Our results suggest that exposure to waterborne Cd at environmentally realistic levels (2 μg l–1) can disrupt the normal behavioural and physiological responses of fish to alarm substance and can thereby alter predator-avoidance strategies, with potential impacts on aquatic fish communities.

A simple and fast synthesis of radioactive methylmercury is presented. It is based on the methylation of inorganic 203Hg(II) by methylcobalamin and isolation of resulting CH3203Hg(II) in a single extraction step. Time required is less than 4 hours and the final yield is ⩾90%. © 1997 John Wiley & Sons, Ltd.

We fed immature 1+ arctic charr with a single dose of methyl[203Hg]mercury (MeHg) and quantified distribution kinetics with a new and simple three-compartment caternary model having well-perfused viscera and blood as the central compartment (VB), whereas gut (G) and the rest of body (R) constituted the peripheral compartments. The model accurately described distribution kinetics of MeHg in the fish, using either data of MeHg content in compartments or blood concentration data. Despite the known fast translocation of MeHg between binding sites at the molecular level, its translocation rate between compartments was surprisingly slow, 27 days being needed to complete 95% of the transfer from gut to blood and 48 days for the subsequent transfer to compartment R. This probably results from a limitation of the stepwise transfer rate of MeHg from red blood cells, which contain most of blood MeHg, to plasma and then to tissues due to low plasmatic concentration of small mobile sulfhydryl ligands. The model presented is a convenient tool that could be used to compare the fate of MeHg and other organometals, such as butyltins and alkylleads, in various aquatic and terrestrial animal species.

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ABSTRACT-Pharmacokinetics and distribution of a 5 pg dietary dose of tributyltin (ll3Sn-TBT) and methylmercury [Me2":'Hg) were studied over 4 2 d in the American plaice Hjppoglossoides platessoides, using in vivo gamma counting, whole-body autoradiography, and a 2-compartment model. The average retention efficiency of TBT was 42'!~,, compared with 88"; for Mcl-lg. Both organometals were distributed to the entire body of the fish. Distribution proceeded at a faster rate for TBT. 95'1; of the stcady state distribution being reached within 5 to 10 d. compared with 29 to 41 d for MeHg. Elimination of TBT was characterised by half-life values ranging from 15 to 77 d. Absorption of dietary TBT from the intestinal lumen appears to be limited by ~t s molecular size, whereas its fast translocatlon rate in the body of fish might be related to specific properties of the intestinal epithelium-blood interface or to cotransport with lipids. Our data also indicated that butyltins in the viscera were partitioned between 2 kinetically distinct pools; one that was eliminated rapidly and one that was stored or eliminated at a very slow rate, probably as a consequence of TBT metabolism. The overall biomagnification factor for the transfer of TBT from sediments to benthic invertebrates to the American plaice may be > l . This indicates that the trophic transfer of sedimentary TBT in the manne benthic food web is potentially significant.