A First Glimpse on Cold-Adapted PCB-Oxidizing Bacteria in Edmonson Point Lakes (Northern Victoria Land, Antarctica)

Antarctic freshwater ecosystems are especially vulnerable to human impacts. Polychlorobiphenyls (PCBs) are persistent organic pollutants that have a long lifetime in the environment. Despite their use having either been phased out or restricted, they are still found in nature, also in remote areas. Once in the environment, the fate of PCBs is strictly linked to bacteria which represent the first step in the transfer of toxic compounds to higher trophic levels. Data on PCB-oxidizing bacteria from polar areas are still scarce and fragmented. In this study, the occurrence of PCB-oxidizing cold-adapted bacteria was evaluated in water and sediment of four coastal lakes at Edmonson Point (Northern Victoria Land, Antarctica). After enrichment with biphenyl, 192 isolates were obtained with 57 of them that were able to grow in the presence of the PCB mixture Aroclor 1242, as the sole carbon source. The catabolic gene bphA, as a proxy for PCB degradation potential, was harbored by 37 isolates (out of 57), mainly affiliated to the genera Salinibacterium, Arthrobacter (among Actinobacteria) and Pusillimonas (among Betaproteobacteria). Obtained results enlarge our current knowledge on cold-adapted PCB-oxidizing bacteria and pose the basis for their potential application as a valuable eco-friendly tool for the recovery of PCB-contaminated cold sites.

Assessment of concentration and distribution of total mercury and polychlorinated biphenyls in Green Bay, Wisconsin, USA

Under the 1987 Great Lakes Water Quality Agreement, the lower Green Bay and Fox River estuary have been labeled as areas of concern due to the contamination of mercury and polychlorinated biphenyls (PCBs) from industrialization. These pollutants pose substantial health and environmental hazards for the Green Bay region. The PCBs reported in this region, including Aroclor 1242, are known to trigger carcinogenic responses in animals and mercury targets the central nervous system and vital organs. Furthermore, these compounds are extremely difficult to remove from the environment once introduced. Extensive remedial actions have been implemented including dredging sediments in the Lower Fox River from DePere to Green Bay. The purpose of this study is to assess the concentration and distribution of Aroclor 1242 and total mercury in the Green Bay region sediments and pore waters and to assess the impact of interventions and the natural rates of change previously found.

Method Validation for Analysis of Aroclor 1260 in Transformer Oil using Gas Chromatography – Electron Capture Detection

Since early 1980’s, the production and usage of Polychlorinated biphenyls (PCBs) have been banned throughout the world due to its carcinogenicity to humans and animals. However, due to the large half-lives of PCBs, large amounts of stocks are still available in storage. This study presents the validation data of the method developed for analysis of Aroclor 1260 in transformer oils in order to determine the concentrations for systematic disposal and destruction.The transformer oil samples were prepared according to the ASTM D 4059 with few modifications. PCBs in transformer oils were extracted with iso-octane followed by deactivated florisil cleanup and detection by GC – ECD using HP 5 GC column (30 m x 0.32 mm x 0.25 μm). The study was performed under matrix matched condition to eliminate the matrix effect that was found to be significant. The method was found linear over a wide working range from 2.5 ppm – 100 ppm with a regression coefficient of 0.994 and a lower limit of determination of 2.5ppm. Method showed satisfactory repeatability with relative standard deviation below 7% over the entire working range. Accuracy of the method was assured using spike recoveries at 5 ppm, 10 ppm and 50 ppm with 85%, 105% and 93% respectively. The selectivity of Aroclor 1260 was confirmed against Aroclor 1254 and Aroclor 1242 considering uniquely identified non – overlapping chromatographic peaks. Based on the performance characteristics, this method can be suggested as an accurate and precise methodology to analyze Aroclor 1260 present in transformer oil.

The toxic effects of polychlorinated biphenyl (Aroclor 1242) on Tm3 Leydig cells

Polychlorinated biphenyls (PCBs) are ubiquitous and persistent environmental contaminants that disrupt endocrine function in biological systems, especially in the male reproductive system. Previous studies on the reproductive toxicity of PCBs have focused on the impairment of spermatogenesis, disruption of steroidogenesis, decreased sperm number, and infertility. Aroclor 1242 is a commercial mixture with an average of 42% chlorine by weight. The purpose of the present study was to elucidate the hazardous effects of Aroclor 1242 on Leydig cells through an evaluation of cell viability, lipid peroxidation, hydroxyl radicals, H2O2 production, antioxidant enzymes, and steroidogenic enzymes. Leydig cells were exposed to Aroclor 1242 for 24 h under basal and luteinizing hormone-stimulated conditions at different concentrations (ranging from 10−16 M to 10−6 M). After incubation, Leydig cells were measured for cell viability, lipid peroxidation, reactive oxygen species (hydroxyl radical and H2O2), antioxidant enzymes (catalase, superoxide dismutase, glutathione peroxidase, and glutathione-S-transferase), and steroidogenic enzymes (3β-hydroxysteroid dehydrogenase [HSD] and 17β-HSD). The results showed that cell viability was reduced only at Aroclor 1242 concentrations of 10−6 M and 10−8 M, whereas lipid peroxidation and reactive oxygen species increased relative to the concentration. Furthermore, antioxidant systems and steroidogenesis were interrupted to varying degrees, relative to the concentration. These findings suggest that exposure to Aroclor 1242 at high concentrations may result in detrimental effects to Leydig cell homeostasis. In addition, Aroclor 1242 may impair steroidogenesis, especially testosterone biosynthesis, by inhibiting two important steroidogenic enzymes.