Assessment of chlorinated pesticide exposure to white-rumped vulture Gyps bengalensis in India.

Populations of the critically endangered white-rumped vulture (WRV) Gyps bengalensis have declined drastically due to the use of diclofenac for veterinary purposes in Indian subcontinent. Thirty-two dead WRVs collected from three states, namely Gujarat, Assam and Tamil Nadu in India between 2011 and 2014 were investigated to understand the role of diclofenac in the death, and the results were published. Furthermore, since organochlorine pesticides have been linked to long-term impact on populations in many species of birds across the globe, available tissues of 21 WRVs were tested also for six organochlorine pesticides (DDT, HCH, endosulfan, heptachlor, dieldrin and dicofol) and chlorpyrifos. All vultures were found to have had one or more detectable levels of pesticides in their tissues except one. Similarly, all the pesticides included in the study were detected in at least one of the vultures analysed. DDT (95.2%) was the most frequently detected pesticide followed by HCH (90.5%), and DDT (73.6%) contributed the most to the total pesticide load. Total pesticide load ranged between below detection limit (BDL) and 8753.4 ng/g. High levels of total pesticide load recorded in gut contents showed recent exposure to these legacy pesticides even long after their ban. However, it is perceived that studied pesticides' exposure to birds and their presence in the environment is in decreasing trend in India. Although, varying levels of pesticides were detected, all of which were below the levels reported to be toxic, and also reported earlier in the same species in India. Recorded levels may not create a problem to vultures unlike diclofenac; nevertheless, as continued exposure to the pesticides studied may lead to sub lethal effects in birds, it is prudent to monitor these pesticides along with new generation pesticides and NSAIDs in the critically endangered white-rumped vulture in India, towards its conservation.

Nimesulide poisoning in white-rumped vulture Gyps bengalensis in Gujarat, India.

Population of white-rumped vulture has not recovered in India to a desired level even after diclofenac was banned in 2006. During 2019, there were two known separate incidents of white-rumped vulture mortality involving four white-rumped vultures in Gujarat. After post-mortem examinations, tissues of all four vultures were received for toxicological investigation at the National Centre for Avian Ecotoxicology, SACON. Tissues were screened for a set of toxic pesticides, and none of them was at detectable level. Subsequently, the tissues were analysed for thirteen NSAIDs and paracetamol. Of all the drugs tested, only nimesulide was detected in all the tissues (17-1395 ng/g) indicative of exposure. Visceral gout was also observed in all the four vultures during post-mortem. Residues of nimesulide in tissues with symptoms of gout indicated that the vultures died due to nimesulide poisoning. Although, other than diclofenac, many NSAIDs are suspected to be toxic to white-rumped vultures, only nimesulide is reported in the recent past with clear symptom of gout in wild dead white-rumped vultures similar to diclofenac. Since, nimesulide appears to act similar to diclofenac in exerting toxic effects, if veterinary use of nimesulide continues, white-rumped vulture are bound to suffer. Hence, it is recommended that nimesulide should be banned by the government to conserve white-rumped vulture in the Indian subcontinent. Further, an effective system is recommended to be put in place to collect the tissues of dead vultures for toxicological investigations and eventual conservation of the critically endangered species.

Variation in Polycyclic Aromatic Hydrocarbon Contamination Between Native and Introduced Species of Fishes of Pallikaranai Wetland, Chennai, Tamil Nadu, India.

The impacts of invasive fish species on recipient communities are mostly considered a threat to the biodiversity of freshwater systems. A characteristic of introduced species turning invasive is their higher tolerance to environmental stressors. To understand if non-native fishes in Pallikaranai wetland, Tamil Nadu, India, are more tolerant to anthropogenic pressures in the Wetland, we assessed the variation in Polycyclic Aromatic Hydrocarbon contamination between introduced and native fish species. Mean levels of Naphthalene, fluorene, phenanthrene, anthracene, pyrene, and total PAH in samples of introduced species were higher than native species, while High Molecular weight PAH and carcinogenic PAH4 were higher in native fish species. The data was also analysed to assess if co-variates (organs, seasons, and sex) affected PAH accumulation patterns in non-native species. It was observed that only organs, sex, and year contributed significantly.

Organochlorine Pesticide Residues Among Colonial Nesting Birds in Tamil Nadu, India: A Maiden Assessment from Their Breeding Grounds.

Use of pesticides continues to be indiscriminate, and birds are one of the worst affected non-targeted organisms. Information on the ill effects of pesticides on birds far from desired in India. Despite the presence of a wide variety and number of birds, there is exceedingly little data on organochlorine pesticide (OCP) residues in colonial nesting birds in sanctuaries of India. A total of 76 individuals belonging to 14 species of birds found dead between March 2008 and March 2010 were analyzed for pesticide residues in various tissues. Of all the OCPs analyzed, concentration of HCH was found to be the highest. Magnitude of contamination varied widely among species. Accumulation pattern of OCPs in colonial nesting birds was in the order ∑HCH > ∑endosulfan > ∑DDT > heptachlor epoxide > dieldrin. Pesticides, namely p,p-DDE and ß-HCH contributed most towards the total OCPs. Concentrations of DDT and its metabolites, HCH and isomers, dieldrin, and heptachlor epoxide were lower than the concentrations reported for various species of birds elsewhere in India. Although the sanctuaries presently studied have official boundaries, physical demarcations are missing and there are no proper earthen dykes particularly in Vedanthangal and Koonthankulam Bird Sanctuaries. During monsoon, runoff not only floods the Sanctuaries but also the cultivated areas nearby. Run off brings in residues of pesticides and fertilizers from the agricultural lands into the sanctuaries. Although OCP results in this study were below threshold limits, it may be noted that the long duration exposure even to low levels of pesticides could create a significant impact at population level. Hence, earthen dykes need to be built to avoid agricultural runoff entering the Sanctuary and also help to hold sufficient amount of water for breeding birds.

Incidences of mortality of Indian peafowl Pavo cristatus due to pesticide poisoning in India and accumulation pattern of chlorinated pesticides in tissues of the same species collected from Ahmedabad and Coimbatore.

Incidences of mortality of Indian peafowl Pavo cristatus, the national bird (Schedule I Indian Wild Life Protection Act 1972), are rampant in India. Between January 2011 and March 2017, around 550 peafowl in 35 incidences were reported dead across the country. Due to the non-availability of fresh carcases, poisoning could not be confirmed. Birds which died due to kite string injuries in Ahmedabad (15) and accidents in Coimbatore (5) were tested for residues of chlorinated pesticides, namely hexachlorocyclohexane (HCH), dichloro-diphenyl-trichloroethane (DDT), endosulfan, heptachlor, dicofol, dieldrin and cholipyrifos. The liver, kidney and muscle were the tissues considered to document pesticide load. Total load ranged from BDL to 388.2 ng/g. DDT (95%) and HCH (80%) were detected more frequently. DDT (40%) and endosulfan (26%) contributed maximum to the total pesticide load followed by HCH (21%). Pesticide accumulation pattern among the organs was in the order of liver (123.9 ng/g) > kidney (91.9 ng/g) > muscle (19.5 ng/g) with significant difference (p < 0.05). Peafowl from Ahmedabad had significantly (p < 0.05) higher level of total pesticide (149.0 ng/g) than birds from Coimbatore (47.8 ng/g). Although varying levels of chlorinated pesticide were detected, they were below reported toxic limits. Nevertheless, persistence of chlorinated pesticides and poisoning due to modern pesticides across the entire distribution range of Peafowl in India is a cause for concern.

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.

Distribution of persistent organochlorine chemical residues in blood plasma of three species of vultures from India.

The presence of persistent organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were determined in blood plasma of white-backed vulture Gyps bengalensis, Egyptian vulture Neophron percnopterus, and griffon vulture Gyps fulvus collected from Ahmedabad, India. All the samples had varying levels of organochlorine pesticides and PCBs. Statistically significant (P<0.05) differences among species were detected for beta-hexachlorocyclohexane (ß-HCH), ∑HCH, and dichloro-diphenyl-trichloroethane (DDT). The mean concentration of ∑HCH, ∑DDT, and ∑PCBs among plasma ranged from 43.7 to 136, 8.8 to 64.8, and 226 to 585 ng/ml, respectively. Among the various OCPs analyzed, 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (p,p'-DDE) was detected most frequently. The concentrations of cyclodiene insecticides detected were lower than the other organochlorine residues. The levels of pesticides measured in plasma samples of three species of vulture were comparable to the results documented for a number of avian species and were lower than those reported to have deleterious effects on survival or reproduction of birds. Although no threat is posed by any of the organochlorine pesticides detected, continuous monitoring of breeding colonies is recommended. This study is also the first account of a comprehensive analysis of toxicants present in blood plasma of vulture species in India. The values reported in this study can serve as guidelines for future research in general as well as control values during the analysis of samples obtained from birds in the event of suspected organochlorine poisoning.

Organochlorine pesticide residues in inland wetland fishes of Karnataka, India and their implications on human dietary intake.

As part of a larger study assessing contamination status of inland wetlands of India, we evaluated the organochlorine pesticide (OCP) residues in fishes collected from different inland wetlands in Karnataka, India and their suitability for human consumption. Among the OCPs tested, isomers of hexachlorocyclohexane (HCH) were the most frequently detected with ß- and γ-HCH as the main pollutants. Average concentration of ∑HCH and ∑DDT ranged from 2.1 to 51.7 µg/kg and below detection level to 12.3 µg/kg respectively. Other organochlorine pesticides such as heptachlor epoxide, dieldrin and endosulphan were found at lower levels. Among various fish species tested, the higher pesticide burden was recorded in Anguilla bicolor bicolour (77.9 µg/kg) and the lower was in Heteropneustes fossilis (2.1 µg/kg). OCPs detected in the present study were well below the tolerance limits recommended for fishes. The calculated daily dietary intake of OCPs in all the species examined was lower than the maximum acceptable dietary intake (ADI) limits prescribed for human consumption. However, continuous monitoring is recommended to facilitate the early identification of risks.

Levels of organochlorine pesticide residues in blood plasma of various species of birds from India.

Concentrations of organochlorine pesticides (OCPs) were measured in blood plasma of 13 species of birds collected from Ahmedabad, India. Among the various OCPs determined, HCHs and its isomers had higher contribution to the total OCPs. Concentration of summation operatorHCHs varied from 11.4 ng/mL in White ibis Threskiornis melanocephalus to 286 ng/mL in Sarus Crane Grus antigone, while summation operatorDDT ranged between 19 ng/mL in Black Ibis Pseudibis papillosa and 147 ng/mL in Painted Stork Mycteria leucocephala. p,p'-DDE was accounted for more than 50% of total DDT in many of the samples analysed. However, a p,p'-DDT to p,p'-DDE ratio higher than one obtained for many species of birds indicates the recent use of DDT in this study region. The concentrations of cyclodiene insecticides, heptachlor epoxide, dieldrin and total endosulfan ranged from 15.8 to 296.2 ng/mL, below detectable level to 15 and 41.1-153.2 ng/mL, respectively. The pattern of total OCP load generally occurred in the following order: granivores < insectivores < omnivores < piscivores < carnivores. Although, the organochlorine residues detected in blood plasma of birds are not indicative of toxicity, the presence of residues in birds over the years (2005-2007) indicates continued exposure to organochlorine compounds. However, continuous monitoring is recommended to facilitate the early identification of risks to the survival of a species.