Accumulation pattern and distribution of polycyclic aromatic hydrocarbons (PAHs) in liver tissues of seven species of birds from Ahmedabad, India, during 2005-2007

Risk assessment and contaminant characterization of PCBs, PAHs, and heavy metals in Pichavaram mangrove sediments, Tamil Nadu, India

The coastal region of Pichavaram, Tamil Nadu, India, is a critical ecological zone that supports diverse marine life and local livelihoods; however, it faces significant environmental challenges due to contamination from persistent toxic substances (PTSs) and heavy metals, which pose serious ecological and human health risks. In the present study, sediment samples collected from the mangrove environment were tested for polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and heavy metals. The results revealed elevated concentrations of ∑PCBs (6-124 ng/g) and ∑PAHs (3.19-37.8 ng/g), alongside heavy metals such as Pb (11-26 μg/g), Cd (0.3-0.87 μg/g), Cu (below detectable levels, bdl)-31 μg/g), Ni (bdl-119 μg/g), and Zn (27-109 μg/g), indicating significant environmental contamination. The total PCB concentrations surpassed the guideline values, indicating potential risks to aquatic life. Elevated naphthalene levels in Kodipallam suggest petrogenic inputs from oil spills and urban runoff. Carcinogenic PAHs, including benzo[a]pyrene, are found at high levels in industrial zones such as Killai, and pose moderate ecological risks. Heavy metals such as As (68-140 μg/g), Cr (25-120 μg/g), and Mn (94-471 μg/g) often exceeded the threshold effect levels (TEL) and probable effect levels (PEL), indicating significant ecological risks and potential human health impacts. Coastal sediment contamination, driven by discharges from chemical industries, oil refineries, metal manufacturing, and agricultural runoff, poses long-term risks to marine life and human health through the bioaccumulation of persistent pollutants in the food chain. This study provides crucial baseline data for future monitoring and emphasizes the need for stricter regulatory measures and pollution management strategies. Recommendations include regular sediment quality monitoring, public awareness campaigns on pollution sources, and sustainable practices to mitigate risks, thereby protecting the coastal environment and local communities.

Wintering loons in South Korea face an ongoing threat from polycyclic aromatic hydrocarbons: Shifting sources and potential DNA damage

Diving birds, particularly those sharing coastal habitats with fishing grounds, are at risk from oil pollution. Despite documented cases of bird mortality, the specific role of oil pollution in these death remains unclear. To address this knowledge gap, this study examined polycyclic aromatic hydrocarbon (PAH) contamination, its sources, and its impact on loon health. An analysis of 86 carcasses from three species of loons revealed drowning as the leading cause of death, followed by oil pollution and unknown debilitation. While liver concentrations of 16 PAHs (∑PAHs) showed no significant variation by sex, location, species, or cause of death, it was evident that wintering loons were exposed to PAH pollution along South Korea's eastern coast. The ratio of low (di- and tri-cyclic) to high (tetra-, penta-, and hexa-cyclic) molecular weight PAHs was approximately 3-5 across all three loon species. From 2010 to 2017, the composition of PAHs shifted, with a decline in low molecular weight PAHs (indicative of petrogenic sources) and a concerning increase in high molecular weight PAHs (associated with pyrogenic sources). This trend coincided with a tenfold increase in the toxic equivalency quotient of benzo[a]pyrene (TEQBaP), despite a decrease in overall ∑PAH concentrations. The detection of benzo[a]pyrene diol epoxide (BPDE)-DNA adducts in some loons further suggests potential genotoxic effects from PAH exposure. These findings underscore the persistent PAH contamination affecting wintering loons. Continued research is crucial to understand the evolving threats posed by PAHs and to support the conservation of these migratory birds along the North America-Asia flyway.

Exploring avian exposure to parent polycyclic aromatic hydrocarbons (PAHs): Using the common eider Somateria mollissima in a global context

Compared to other organic contaminants, birds are rarely studied for their exposure to polycyclic aromatic hydrocarbons (PAHs), mainly due to their effective metabolization of parent PAHs. However, as some studies suggest, exposure to PAHs may result in adverse health effects including decreased survival, especially following oil spills. In the present study, we analyzed samples from a sea duck, the common eider Somateria mollissima including feathers, preen oil, blood, liver and bile, to evaluate whether non- lethally collected samples could be reliably used for avian biomonitoring strategies. Phenanthrene was the only individual PAH detected across sample types, with the highest concentration found in preen gland and the lowest in blood. Significant differences in concentrations were observed between bile vs preen gland and liver vs preen gland, while for most compounds neither blood nor feathers showed detectable levels of parent PAHs. Therefore, the utility of those sample types for PAH exposure assessment may be limited and should be interpreted with caution, moreover as several physiological factors may affect them. Additionally, we also provide a comparison with the available literature to review current avian PAH exposure assessment and outline future research focused needs.

Using homing pigeons to monitor atmospheric organic pollutants in a city heavily involving in coal mining industry

Coal is the most extensively used fossil fuel in China. It is well documented that coal combustion detrimentally affected air quality, yet the contribution of coal mining activity to air pollution is still largely unknown. Homing pigeons have been applied to assess the occurrence of atmospheric pollutants within cities. Herein, we sampled homing pigeons from both urban and mining areas in a typical coal industry city (Datong, China) as biomonitors for assessing local air pollution. Target organic contaminants, including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and organochlorine pesticides (OCPs) were frequently detected in lung, liver, and fat tissues of the pigeons. The pollutants were predominately accumulated in lung, validating that respiration was the main accumulation route for these compounds in homing pigeons. In addition, pathological damage examination in lung and liver tissues revealed that the exposure to atmospheric pollutants impaired pigeon health. While the concentrations of PCBs and OCPs were similar in pigeons from urban and mining areas, the concentrations of PAHs were higher in pigeons from urban area. In contrast, more elevated levels of PBDEs (particularly BDE-209) were found in the mining area, which was consistent with the greater pathological damages and particulate matter levels. Unlike coal combustion, coal mining activities did not increase atmospheric PAH exposure to homing pigeons, but intensified PBDE contamination along with increasing emission of particulate matters. Overall, homing pigeons are promising biomonitors for assessing the respiratory exposure and risk of atmospheric pollutants within cities.

Global DNA methylation changes in rock pigeon (Columba livia) as a sentinel species due to polycyclic aromatic hydrocarbons exposure in Tehran (Iran) as a megacity

Global DNA methylation, as an epigenetic modifications, can be a promising genomic marker for monitoring the contaminants and predicting their adverse health effects. The study aims to assess the effects of 16 PAH concentration on the altered DNA methylation levels in the kidney and liver of rock pigeon (Columba livia), as a sentinel species, from Tehran megacity as well as 40 days benzo(a)pyrene in vitro exposure: (0.1, 2.5, 5, 7.5, and 10 mg kg^-1 bw). Data indicated that the total LMW-PAH (low molecular weight PAHs) group (120.22, 121.34, 103.69, and 128.79 ng g^-1 dw in liver, kidney, skin, and muscle, respectively) in the Tehran samples have higher levels than the other PAHs groups. In addition, the DNA methylation level had negative relation with the total amount of PAHs in liver and kidney. A comparatively higher global DNA hypomethylation (by 8.65% in liver and 3.76% in kidney) was observed in birds exposed to B(a)P. Our results lead us to suggest that DNA hypomethylation in liver and kidney associated with the B(a)P may be useful biomarker discovery (more than the amount of PAH concentration in different tissues of C. livia) in urban areas. In conclusion, based on the overall results assessed, DNA methylation changes in pigeon may show a new target pathway for evaluation of environmental health.

Residues of Diclofenac in Tissues of Vultures in India: A Post-ban Scenario

Populations of three resident Gyps species (Indian white-backed vulture Gyps bengalensis, Indian vulture Gyps indicus, and Slender-billed vulture Gyps tenuirostris) in India have decreased by more than 90% since mid 1990s, and they continue to decline. Experimental studies showed the mortality of vultures to be due to renal failure caused by diclofenac, a nonsteroidal anti-inflammatory drug. India, Pakistan, and Nepal banned the veterinary usage of diclofenac in 2006 to prevent further decline in vulture population. This study was performed to know the current status of the impact of diclofenac on vultures in India. Between 2011 and 2014, 44 vultures comprising two species, namely Indian white-backed vulture (32) and Himalayan griffon Gyps himalayensis (12) were collected dead from Gujarat, Assam, and Tamil Nadu on an opportunistic basis. Kidney and liver tissues and gut content were analysed for diclofenac. Of the 32 dead white-backed vultures analysed, 68.75% of them had diclofenac ranging from 62.28 to 272.20 ng/g. Fourteen white-backed vultures had diclofenac in kidney in toxic range (70-908 ng/g). Of 12 Himalayan griffon studied, 75% of them had diclofenac in the range of 139.69 to 411.73 ng/g. Himalayan griffon had significantly higher levels of diclofenac in tissues than Indian white-backed vultures. It is possible that 14 of 29 white-backed vultures and 9 of 12 Himalayan griffon included in this study died due to diclofenac poisoning. Studies have indicated that diclofenac can continue to kill vultures even after its ban in India for veterinary use.

Homing pigeons as a biomonitor for atmospheric PAHs and PCBs in Guangzhou, a megacity in South China

The occurrence of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyl (PCBs) in urban atmosphere in Guangzhou, China were assessed using homing pigeons as a biomonitor. Contaminant concentrations in lung were significantly higher than those in liver and fat, indicating chemical uptake was mainly through respiratory route. Tricyclic PAHs and low chlorinated PCBs dominated composition of PAHs and PCBs in homing pigeons, similar as their composition in local atmosphere. Different age-dependent bioaccumulation patterns were noted for PAHs and PCBs. For 1-year old homing pigeons, higher levels of PAHs and PCBs in lung and liver tissues were probably ascribed to more intense flying than 5- and 10-year groups. Fat concentrations of PCBs were greater in aged pigeons than 1-year old pigeons, but PAH concentrations in fat slightly decreased in aged pigeons because of relatively fast biotransformation. Overall, homing pigeons could serve as a suitable biomonitor for urban atmospheric contaminants in coastal cities.

CAPSULE

Homing pigeons could serve as a good biomonitor for PAHs and PCBs in urban atmosphere, yet different biotransformation potential of the chemicals caused different bioaccumulation patterns in pigeon fat.

Assessment of the exposure to organochlorine pesticides, PCBs and PAHs in six species of predatory birds of the Canary Islands, Spain

In the present study, we investigated the concentrations and distributions of 57 anthropogenic pollutants, including 23 organochlorine pesticides (OCs), 18 polychlorinated biphenyls (PCBs) and 16 polycyclic aromatic hydrocarbons (PAHs) in liver samples from 102 birds of prey of six species that were found dead or that had died during their stay in the Wildlife Recovery Centers of the Canary Islands (Spain) between 2009 and 2012. The dual goal of this work was to determine the occurrence of these contaminants in these six species of birds of prey, and also whether they can be used as bioindicators for monitoring environmental pollution in the region. We found that Accipiter nisus, Falco pelegrinoides and Falco tinnunculus were the most contaminated species. The profiles of contamination among the species were extremely similar in the case of organochlorine contaminants, with DDT and its metabolites as the most abundant compounds. The contamination by DDT and its metabolites, as well as contamination by dieldrin, could be considered high in these animals, much higher than reports from other regions of the planet, which is in agreement with previous reports from our group regarding humans, food and other animals from this area. In contrast, the contamination by PCBs could be considered extremely low and was probably below the threshold of toxicity for these contaminants. The content of carcinogenic/mutagenic PAHs in these animals was clearly dependent on the feeding pattern of the species; however, the levels were also well below the values that were considered toxic in predictive models. This study represents the first report of contamination by PAHs in all these species and is also the first report of PCB levels in Barbary Falcons.

Levels of polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and organochlorine pesticides in various tissues of white-backed vulture in India

This study provides information on the current status of contamination by polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and organochlorine pesticides (OCPs) in the tissues of endangered White-backed Vulture Gyps bengalensis in India. Chemical analyses revealed detectable amounts of PAHs, PCBs, and OCPs. Concentration ranges of ∑PAHs, ∑PCBs, and ∑OCPs in tissues were 60–2037 ng/g, 30–5790 ng/g, and 3.2–5836 ng/g wet weight, respectively. 1,1-Dichloro-2,2-bis(p-chlorophenyl)ethylene (p,p′-DDE) concentrations ranged from below detectable level to 599 ng/g wet weight, representing more than 90% of the total dichlorodiphenyltrichloroethane (DDT). Among the various OCPs analyzed, p,p′-DDE was detected most frequently. All the contaminants recorded show higher accumulation in liver than other tissues. Levels of contaminants measured in the tissues of vulture are comparable with the levels documented in a number of avian species and are lower than those reported to have caused deleterious effects. Although no threat is expected from the current level of contamination, the presence of varying levels of contaminants and their additive or synergistic toxicity is a cause of concern to vultures. Values reported in this study can serve as guideline for future research.