Biological responses of midge (Chironomus riparius) and lamprey (Lampetra fluviatilis) larvae in ecotoxicity assessment of PCDD/F-, PCB- and Hg-contaminated river sediments.

We evaluated the utility of chironomid and lamprey larval responses in ecotoxicity assessment of polychlorinated dibenzo-p-dioxins, dibenzofurans (PCDD/F)-, polychlorinated biphenyls (PCB)- and mercury (Hg)-contaminated river sediments. Sediment samples were collected from the River Kymijoki with a known industrial pollution gradient. Sediment for the controls and lamprey larvae were obtained from an uncontaminated river nearby. Contamination levels were verified with sediment and tissue PCDD/F, PCB and Hg analyses. Behaviour of sediment-exposed chironomid and lamprey larvae were measured with Multispecies Freshwater Biomonitor© utilizing quadrupole impedance conversion technique. In addition, mortality, growth and head capsule deformity incidence of chironomids were used as ecotoxicity indicators. WHOPCDD/F+PCB-TEQ in the R. Kymijoki sediments ranged from the highest upstream 22.36 ng g(-1) dw to the lowest 1.50 ng g(-1) near the river mouth. The sum of PCDD/Fs and PCBs correlated strongly with Hg sediment concentrations, which ranged from <0.01 to 1.15 µg g(-1). Lamprey tissue concentrations of PCDD/Fs were two orders and PCBs one order of magnitude higher in the R. Kymijoki compared to the reference. Chironomid growth decreased in contaminated sediments and was negatively related to sediment ∑PCDD/Fs, WHOPCDD/F+PCB-TEQ and Hg. There were no significant differences in larval mortality or chironomid mentum deformity incidence between the sediment exposures. The distinct behavioural patterns of both species indicate overall applicability of behavioural MFB measurements of these species in sediment toxicity bioassays. Chironomids spent less and lampreys more time in locomotion in the most contaminated sediment compared to the reference, albeit statistically significant differences were not detected. Lamprey larvae had also a greater activity range in some of the contaminated sediments than in the reference. High pollutant levels in lamprey indicate risks for biomagnification in the food webs, with potential health risks to humans consuming fish.

Pollutant concentrations in placenta.

Unborn children are exposed to environmental pollutants via the placenta, and there is a causal relationship between maternal intake of pollutants and fetal exposure. Placental examination is an effective way for acquiring data for estimating fetal exposure. We analyzed the concentrations of 104 congeners of persistent organic pollutants, seven organotin compounds, five heavy metals, and methylmercury in 130 randomly selected placentas. Additionally, we examined similarities between pollutant concentrations by analyzing correlations between their placental concentrations. Our results yield new information for conducting contaminant risk assessments for the prenatal period. Out of the 117 individual persistent organic pollutants or metals assayed, 46 could be detected in more than half of the placentas. Moreover, dichlorodiphenyldichloroethylene (p,p'-DDE) was found in all placentas. The data indicates that fetal exposure to dioxins and furans (PCDD/Fs), polychlorinated biphenyls (PCBs), p,p'-DDE, and methylmercury depends on the mother's parity, and age. We also conclude that sources of the above four pollutants are similar but differ from the sources of polybrominated diphenyl ethers.

Effects of docosahexaenoic acid and methylmercury on child's brain development due to consumption of fish by Finnish mother during pregnancy: a probabilistic modeling approach.

Fish contains both beneficial substances e.g. docosahexaenoic acids but also harmful compounds e.g. methylmercury. Importantly, the health effects caused by these two substances can be evaluated in one common end point, intelligence quotient (IQ), providing a more transparent analysis. We estimated health effects of maternal fish consumption on child's central nervous system by creating a model with three alternative maternal fish consumption scenarios (lean fish, fatty fish, and current fish consumption). Additionally, we analyzed impacts of both regular fish consumption and extreme fish consumption habits. At the individual level, the simulated net effects were small, encompassing a range of one IQ point in all scenarios. Fatty fish consumption, however, clearly generated a beneficial net IQ effect, and lean fish consumption evoked an adverse net IQ effect. In view of the current fish consumption pattern of Finnish mothers the benefits and risks seem to more or less compensate each other. This study clearly shows the significance of which fish species are consumed during pregnancy and lactation, and the results can be generalized to apply to typical western population fish consumption habits.

Quantitative MRI of the hippocampus and amygdala in severe depression.

BACKGROUND: There is little evidence to support possible structural changes in the amygdala and hippocampus of patients with severe depression. METHODS: Quantitative MRI of the amygdala and hippocampus, as well as proton spectroscopy (MRS) of mesial temporal structures were studied in 34 drug-resistant in-patients with major depression and compared with 17 age-matched controls. Volumetric MRI data were normalized for brain size. RESULTS: The volume of the left hippocampus was significantly smaller in the patients compared with the controls. Both groups exhibited similar significant hippocampal asymmetry (left smaller than right). The patients, but not the controls, had significant asymmetry of the amygdalar volumes (right smaller than left). No differences were observed between the patients and controls in the T2 relaxation times for the hippocampus and amygdala. Mesial temporal lobe MRS revealed a significantly elevated choline/creatine ratio in the patients compared with the controls. CONCLUSIONS: This quantitative MRI study provides support for a possible association between structural and biochemical substrates and severe drug-resistant major depression.