Polychlorinated biphenyls (PCBs) are classified as one the most extremely regulated anthropogenic contaminants and they have been deeply probed in aquatic ecosystems. However, there is very limited ...understanding of the population level effects of exposure to PCBs on terrestrial animal species and this has been unanimously indicated as a critical gap in ecological risk assessment. To bridge this information gap, we integrated an individual-based model (IBM) framework into toxicokinetics resulting in a deeper ecological insight to simulate the accumulation of a hypothetical PCB in a terrestrial three-level food chain at the population level. We then validated our simulated system utilizing the observed field bioaccumulation factors in a well-studied terrestrial prey-predator, caribou-wolf. Key findings of the present study indicate that in a PCB-contaminated environment, where all food sources contain some amount of contaminants, producing more offspring results in lower toxic concentration in herbivores (prey) and higher concentration in carnivores (predator). Our novel contribution in this work is that we have achieved a validated system that enables us to investigate toxicokinetics in any animal species involved in a prey-predation interaction by providing lipid, non-lipid, and water fractions in their bodies. Additionally, we demonstrated how using IBM modelling approach could facilitate ecological risk assessment by offering detailed information of generations spanning as many years as required.
Subcooled-liquid vapor pressures and Henry's law constants were determined for individual chlorinated n-alkanes, including 1,10-dichlorodecane and 1,12-dichlorodecane; components of polychlorinated ...decane, undecane, and dodecane mixtures; and a radiolabeled polychlorinated dodecane mixture. The vapor pressure gas-liquid chromatography correlation technique was employed, along with the gas-sparging technique. In terms of vapor pressure, a 2.3-fold decrease was found for each additional carbon in a molecule containing the same number of chlorines, and a 4.4-decrease was found for each additional Cl added to a C chain length. The compounds exhibited a decreasing trend in Henry's law constants with increasing degree of chlorination. All vapor-pressure and Henry's law constant data are tabulated.
Subcooled-liquid aqueous solubilities were determined for polychlorinated decanes, obtained from simple mixtures using two independent techniques: correction of the apparent solubilities obtained ...from the generator column technique by accounting for the mixture effect, and the ratio of the subcooled-liquid vapor pressure to Henry's law constants. Results showed that the chlorinated alkane mixture exhibited a cosolute effect on the apparent solubilities of individual components. The aqueous solubilities increased with increasing degree of chlorination.
Changes in the quality of eggs of birds exposed to polychlorinated biphenyls (PCBs) have been described, but have never been directly attributed to PCBs. Polychlorinated biphenyl residues in eggs ...have been associated with reduced reproductive success and embryonic deformities in wild birds. Egg size and composition, specifically the amount of albumen, yolk, and water in an egg, also influence the growth and viability of embryos and hatchlings, and consequently the reproductive success of birds. To deter mine whether PCB exposure of adult birds affected the size and composition of their eggs, 25 pairs of captive American kestrels (Falco sparverius) were fed a mixture of PCB-spiked (1248:1254:1260) food to give an approximate exposure of 7 mg/kg body weight/d, beginning 1 mo prior to pairing, and continuing throughout the courtship, egg-laying, and incubation periods. This dietary level in the adult female kestrels resulted in mean total PCB residues in the eggs of 34.1 µg/g wet weight (geometric mean), which is environmentally relevant. PCB residues in eggs increased with the time of female exposure to the contaminated diet and laying date. Variation in egg size within PCB clutches was significantly greater than within control clutches, although absolute egg mass and volume did not differ markedly by treatment. Only infertile eggs and only one egg per clutch were used for egg composition analysis. Yolks in the PCB-contaminated eggs were heavier, with less wet and dry albumen relative to control eggs. Water content and eggshell thickness were not significantly affected by PCB exposure. These results suggest that eggs from the PCB treatment have relatively more lipid and less protein available for embryonic development. Changes in egg composition were not associated with egg size, lay date, ambient temperature, humidity, or precipitation, which are factors known to affect these variables in bird eggs. The PCB-induced changes in egg composition described here provide insight into possible mechanisms contributing to reduced reproductive performance in wild birds exposed to PCBs.
