Evolutionary toxicology: contaminant-induced genetic mutations in mosquitofish from Sumgayit, Azerbaijan.

This study builds on a long-term program that has shown Sumgayit, Azerbaijan to contain wetlands with high levels of a diversity of chemical contaminants. Previous contaminant and biomarker studies of turtles and frogs showed a correlation between somatic chromosomal damage and chemical contaminants at Sumgayit. The objective of this study was to determine if a recently arrived species (mosquitofish) has genetic impacts similar to native species (marsh frogs) thus confirming the pattern is not the result of historical events such as glacial cycles, but is associated with recent chemical contamination. Nucleotide sequences of the mtDNA control region of invasive mosquitofish (Gambusia holbrooki) from Sumgayit were compared to mosquitofish from pristine sites in Europe and Azerbaijan and to native North American populations. Persistent heteroplasmy for a hyper-mutable simple sequence repeat and low haplotype and nucleotide diversities were observed in all invasive populations. However, Sumgayit possessed four de novo haplotypes and heteroplasmic conditions. All of the observed variable nucleotide positions were within or adjacent to a cytosine mononucleotide repeat. This repeat was within a conserved secondary structure; the region likely undergoes expansion and contraction at a rate sufficient to prevent fixation of the common 1/3 heteroplasmy. Whereas the 1/3 heteroplasmy appeared coincident with the establishment of mosquitofish in Europe, other forms of heteroplasmy resulted from contaminant-induced de novo mutations in Sumgayit. We conclude that Sumgayit is a mutational hotspot caused by legacy contaminants from chemical factories from the era of the Soviet Union.

A comparison of concentrations of polycyclic aromatic compounds detected in dust samples from various regions of the world.

Settled house dust can be a source of human exposure to toxic polycyclic aromatic hydrocarbons (PAHs) through non-dietary ingestion and dermal contact. Information regarding the concentrations of various contaminants in house dust would be useful in estimating the risk associated with exposure to these compounds. This study reports on the surface loading, variability and distribution of PAHs in settled house dust collected from homes in three locations: Sumgayit, Azerbaijan; Shanxi Province, China; and southern Texas, United States. The highest PAH floor surface loadings were observed in China, followed by Azerbaijan and Texas. Median concentrations of high molecular weight (four ring and larger) PAHs ranged from a low of 0.11 microg/m(2) in Texas, to 2.9 microg/m(2) in Azerbaijan and 162 microg/m(2) in China. These trends in total surface loading and relative carcinogenicity indicate that the risk of health effects from exposure to PAHs in house dust is highest in the Chinese population and lowest in the Texas population. As anticipated, variability among dust samples from different houses within the same region was high, with coefficients of variation greater than 100%. Alkylated PAHs comprised 30-50% of the total mass of PAHs. Based on a comparison of the composition of specific components, PAHs in China and Azerbaijan were determined to be derived mainly from combustion sources rather than from unburned fossil fuels such as petroleum. These results, coupled with ongoing investigation of appropriate PAH exposure biomarkers in humans, will guide future efforts to identify ways to reduce exposures in the study areas.

Evolutionary toxicology: population-level effects of chronic contaminant exposure on the marsh frogs (Rana ridibunda) of Azerbaijan.

We used molecular methods and population genetic analyses to study the effects of chronic contaminant exposure in marsh frogs from Sumgayit, Azerbaijan. Marsh frogs inhabiting wetlands in Sumgayit are exposed to complex mixtures of chemical contaminants, including petroleum products, pesticides, heavy metals, and many other industrial chemicals. Previous results documented elevated estimates of genetic damage in marsh frogs from the two most heavily contaminated sites. Based on mitochondrial DNA (mtDNA) control region sequence data, the Sumgayit region has reduced levels of genetic diversity, likely due to environmental degradation. The Sumgayit region also acts as an ecological sink, with levels of gene flow into the region exceeding gene flow out of the region. Additionally, localized mtDNA heteroplasmy and diversity patterns suggest that one of the most severely contaminated sites in Sumgayit is acting as a source of new mutations resulting from an increased mutation rate. This study provides an integrated method for assessing the cumulative population impacts of chronic contaminant exposure by studying both population genetic and evolutionary effects.

Chromosomal damage in two species of aquatic turtles (Emys orbicularis and Mauremys caspica) inhabiting contaminated sites in Azerbaijan.

The Caspian region and specifically the Apsheron peninsula of Azerbaijan are known to be polluted with a variety of environmental contaminants. These complex mixtures of contaminants make risk assessment difficult. We used the flow cytometry method (FCM) and the micronucleus assay (MN) to assess chromosomal damage in aquatic turtles (Emys orbicularis, the European pond turtle; and Mauremys caspica, the Caspian turtle) inhabiting contaminated wetlands in Azerbaijan. Evidence of genetic damage was found for two sites, Neftchala and Sumgayit, relative to a reference site, Ali Bairamly. Sediment samples from each site were analyzed for PAHs and mercury to evaluate potential contaminant associations with genetic damage. A significant positive correlation was documented between three-ring PAH sediment concentrations and FCM estimates of chromosomal damage in E. orbicularis. These data combine to show that the contaminated wetlands in Sumgayit and Neftchala are genotoxic and that three-ring PAHs are likely a significant influence on observed genotoxicity.

Patterns of genotoxicity and contaminant exposure: evidence of genomic instability in the marsh frogs (Rana ridibunda) of Sumgayit, Azerbaijan.

The wetlands of Sumgayit in the Azerbaijan Republic contain complex mixtures of contaminants, including polycyclic aromatic hydrocarbons (PAHs), mercury, organochlorine pesticides, and polychlorinated biphenyls. Marsh frogs (Rana ridibunda) were collected from several contaminated wetlands within the city as well as from two reference sites outside the city. Sediment samples revealed heterogeneous patterns of PAH and mercury concentrations throughout Sumgayit, with the highest levels occurring east of the Sumgayit River, within the industrial zone. Flow cytometry and micronucleus assay revealed elevated estimates of genetic damage in frogs from the wetlands east of the Sumgayit River compared to frogs from the reference sites. Flow cytometric data showed a significant correlation with sediment mercury concentrations, whereas population micronucleus frequencies were significantly correlated with high-molecular-weight PAHs.

Chemical contaminants and their effects in fish and wildlife from the industrial zone of Sumgayit, Republic of Azerbaijan.

Sediment from a wetland adjacent to an industrial wastewater treatment plant in Sumgayit contained concentrations of total PAHs, total PCBs, aldrin, biphenyl, chlordane, DDT, mercury, beta-endosulfan, heptachlor, alpha-hexacyclohexane (alpha-HCH), gamma-HCH, and several individual PAH congeners that were elevated relative to published sediment quality guidelines. Chemical analyses of tissues from European pond turtles (Emys orbicularis) had increased levels of many of the same chemicals including aldrin, chlordane, heptachlor, alpha-HCH, total PCBs, total PAHs, and mercury, compared to reference turtles. In addition, turtle tissues contained elevated levels of DDD, hexachlorobenzene (HCB), and pentachlorobenzene that were not elevated in the sediment sample. Some differences were observed in contaminant levels between European pond turtles and Caspian turtles (Mauremys caspica) taken from the ponds in Sumgayit. Salmonella/microsome mutagenicity assays on pond sediments were negative or weakly positive. Micronuclei in European pond turtles were statistically correlated with tissue levels of mercury, heptachlor, DDD, HCB, and trans-nonachlor. Microcosm experiments using Russian sturgeon (Acipenser gueldenstaedtii) showed a positive dose-response relationship between exposure to suspended contaminated pond sediment and acute toxicity. Chemical and biological assays used in this study show the industrial area of Sumgayit is heavily contaminated with a complex mixture of toxic pollutants. Exposure to contaminated sediments produced acute effects in Russian sturgeon, but genotoxic effects appear to be slight.