Persistent organochlorine pesticide residues in tissues and eggs of white-backed vulture, Gyps bengalensis from different locations in India

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.

Old World Vultures Reflect Effects of Environmental Pollutants Through Human Encroachment

African wildlife face challenges from many stressors including current and emerging contaminants, habitat and resource loss, poaching, intentional and unintentional poisoning, and climate-related environmental change. The plight of African vultures exemplifies these challenges due to environmental contaminants and other stressors acting on individuals and populations that are already threatened or endangered. Many of these threats emanate from increasing human population size and settlement density, habitat loss from changing land use for agriculture, residential areas, and industry, and climate-related changes in resource availability. Environmental chemicals that are hazardous include legacy chemicals, emerging chemicals of concern, and high-volume-use chemicals that are employed as weed killers and in other agricultural applications. Furthermore, there are differences in risk for species living in close proximity to humans or in areas affected by habitat loss, climate, and industry. Monitoring programs are essential to track the status of nesting pairs, offspring survival, longevity, and lifetime productivity. This is important for long-lived birds, such as vultures, that may be especially vulnerable to chronic exposure to chemicals as obligate scavengers. Furthermore, their position in the food web may increase risk due to biomagnification of chemicals. We review the primary chemical hazards to Old World vultures and the interacting stressors affecting these and other birds. Habitat is a major consideration for vultures, with tree-nesters and cliff-nesters potentially experiencing different risks of exposure to environmental chemicals. The present review provides information from long-term monitoring programs and discusses a range of these threats and their effects on vulture populations. Environ Toxicol Chem 2022;41:1586-1603. © 2022 SETAC.

Levels and distribution pattern of organochlorine pesticide residues in eggs of 22 terrestrial birds from Tamil Nadu, India

Long-term monitoring is essential to assess the patterns and distribution of the residues of organochlorine pesticides (OCPs) in biota. Bird eggs have several advantages than other environmental matrixes, which have been used extensively to portray the accumulation and distribution of OCPs. The present study investigated the organochlorine pesticide (OCP) residues in eggs of 22 species of terrestrial birds collected from Tamil Nadu, India. Eggs found abandoned were collected during nest monitoring between 2001 and 2008 and analyzed for the presence of organochlorine pesticide residues. The results showed that the mean concentrations of total hexachlorohexane (∑HCHs), total dichlorodiphenyltrichloroethane (∑DDTs), heptachlor epoxide, and dieldrin ranged from non-detectable (nd) to 2800 ng/g, nd to1000 ng/g, nd to 700 ng/g, and nd to 240 ng/g on a wet mass (wm) basis, respectively. The variation in magnitude of contamination among the species and feeding guilds were not significantly different (p > 0.05). Among the OCPs analyzed, the residues of β-HCH and p,p'-DDE were found to be the abundant in concentration. Similarly, among various bird species studied, the highest concentrations of ∑OCPs (> 5000 ng/g wm) were recorded in the eggs of gray junglefowl, scaly-breasted munia, and red-whiskered bulbul. This may be due to their widespread occurrence of their habitat at proximity to the agricultural fields, where organochlorines were in use until recently. Among the various contaminants analyzed, concentrations of p,p'-DDE and heptachlor epoxide exceeded the threshold levels of toxicity for wild birds in > 5% of the egg samples. Hence, this study indicates the need for continued monitoring and further systematic ecotoxicological investigation of these compounds not only in eggs but also in other environmental media.

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 β-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.

Organochlorine pesticides in feathers of three raptor species in southern Brazil

In this study, we determined the presence of organochlorine pesticides (OCPs) in back feathers from three raptor species, Phalcoboenus chimango, Milvago chimachima and Caracara plancus. Samples were obtained from live animals and ten OCPs were detected: α-HCH, β-HCH and γ-HCH (lindane), heptachlor, heptachlor epoxide, aldrin, endosulfan I, endosulfan II, endosulfan sulfate and p,p'-DDE. The concentrations found were higher than those reported in other raptor species, and C. plancus showed greater values than P. chimango and M. chimachima for all the substances. These differences may be justified by the species feeding habits and the characteristics of the sampling area, since C. plancus were sampled in an area with a higher concentration of agricultural crops and urbanized environments. In relation to the possible negative effects, four individuals of C. plancus presented DDE values related to sublethal effects for other species. This is the first study reporting OCPs in back feathers of these species in Brazil, and further studies evaluating OCP exposure and related effects are important for a better understanding of the consequences of different OCP concentrations on the health of these species.

The perfect threat: Pesticides and vultures

Probably the most important threat currently affecting vultures worldwide is exposure to pesticides, both accidentally and through deliberate abuse. This is of special concern since around 70% of vulture species are threatened by human activities. However, information about this threat is sparse and geographically biased. We compiled existing knowledge about pesticide exposure in vulture species globally, providing unifying criteria to mitigate this problem with a joint global effort. Most information available about accidental exposure to pesticides in vultures is related to organochlorine pesticides. Non-lethal exposure to these compounds occurs on every continent that vultures inhabit. While concentrations of organochlorine pesticides reported in different samples appear to be too low to produce health impacts, some studies show vultures with levels compatible with health impacts. In addition, there are some reports of vultures contaminated accidentally by anticoagulant rodenticides and external antiparasitic drugs used in veterinary practices. Deliberate abuse of pesticides to poison wildlife also occurs on every continent where vultures live, affecting most (78%) vulture species. However, little information is available for some regions of America, Asia and Europe. The exact number of vultures killed due to deliberate poisoning with pesticides is not well known, but the available figures are alarming (e.g. up to 500 individuals in a single event). The most widely used pesticides affecting vulture populations, and associated with deliberate poisoning, are carbamates and organophosphorus compounds. Of particular concern is the fact that massive poisoning events with these compounds occur, in some cases, within protected areas. This suggests that if this situation is not reversed, some vulture populations could disappear. A combination of measures such as banning pesticides, controlling their distribution-acquisition and environmental education could produce better results that banning pesticides alone. If poisoning with pesticides is not stopped, this threatened avian group could inadvertently go extinct very soon.

Is current information on organochlorine exposure sufficient to conserve birds in India?

Organochlorine compounds (OCs) pose a serious threat towards the wildlife due to their well-known adverse effects. India is the second largest producer of pesticides in Asia, with DDT production still ongoing, and is ranked amongst the leading countries of pesticide consumption. However, a significant data gap in avian biomonitoring studies has been identified in Asia. The objective of this review is to compile and discuss the available literature on concentrations of organochlorine pesticides and PCBs in Indian birds. The review of 18 articles showed that DDTs were the OCs most frequently analysed, followed by HCHs and PCBs (highest hepatic mean values: 11.6, 1.8 and 1.03 µg/g ww, respectively). The most frequently analysed matrix was whole body homogenates, followed by internal tissues. Plasma, eggs, feathers and guano were poorly sampled. The range of sampling years was 1980-2007. In general, hepatic OC concentrations were below the level known to cause adverse effects, although p,p'-DDE in eggs was found in concentrations associated with eggshell thinning. Most of the studies were carried out in Southern India (Tamil Nadu). Out of 106 species studied, house crow (Corvus splendens) was the most frequently monitored. However, the number of individuals sampled per species is generally low and different sample types are used, thus, huge limitations to compare OC exposure exist. This review shows that there is a clear deficit of data on OC concentrations and sublethal effects that needs to be addressed to understand the status of OC exposure, spatio-temporal trends and potential impacts in Indian avifauna.

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.

Changes in eggshell thickness and ultrastructure in the Bearded Vulture (Gypaetus barbatus) Pyrenean population: A long-term analysis

The Spanish Bearded Vulture (Gypaetus barbatus) population has suffered from negative trends in a number of reproductive parameters that could jeopardize its long-term viability. From 1989 to 2012, 27 entire eggs and 63 eggshell fragments were collected from nests after breeding failure and/or fledging. Longer-term changes in eggshell thickness were made by examining 69 eggs collected in Spain from 1858 to 1911, and now held in European museums. Low levels of contamination with organochlorine pesticides and polychlorinated biphenyls were found in whole eggs and in conjunction with the high fertility rates observed in the field (66.7%) do not indicate a population suffering from the effects of organochlorine contamination. However, a decrease in the Ratcliffe Index and eggshell thickness were observed in eggs collected since 2001, increasingly so in samples post-2004, indicating an abrupt loss of egg quality. We found no significant relationship between organochlorine residues and eggshell in any of the variables measured. In contrast, we found a positive relationship between food availability and the Ratcliffe Index, eggshell thickness and eggshell surface area. A density-dependent explanation of reduced egg quality could arise from ecological constraints as the decrease of food resources. The impact of sudden changes in food availability due to sanitary regulations between 2006 and 2011 could be related with the loss of Bearded Vulture egg quality.

Toxicity Assessment on the Levels of Select Metals in the Critically Endangered Indian White-backed Vulture, Gyps bengalensis, in India

To assess the potential contribution of metals to the catastrophic population decline of the White-backed Vulture, Gyps bengalensis, their concentrations in various organs was quantified. Liver, kidney, pectoral muscle, gut contents and femur bone were collected from dead birds between 1999 and 2008. These samples were analysed for lead, cadmium, copper and zinc, which were detected in all organs with no significant variation among tissues or between sexes. Moreover, high lead levels in liver (8.56 µg/g wet weight) and kidney (9.31 µg/g wet weight) in some individuals indicate toxic effects. Nonetheless, the levels of most metals measured in the present study may be considered as normal.

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.

Accumulation pattern of persistent organochlorine pesticides in liver tissues of various species of birds from India

As part of a large study on assessing the impact of environmental contaminants in Indian avifauna, the presence of organochlorine pesticides (OCPs) in liver tissues of 16 species of birds collected from Ahmedabad, India during 2005-2007 was quantified. The higher concentrations of total organochlorine pesticides were detected in livers of shikra Accipiter badius (3.43 ± 0.99 μg/g wet wt) and the lower levels in white ibis Pseudibis papillosa (0.02 ± 0.01 μg/g wet wt). Marked differences in the concentrations of total OCPs occurred among species (p < 0.05). Concentrations of DDT and its metabolites, hexachlorocyclohexane (HCH) and isomers, dieldrin, and heptachlor epoxide were lower than the concentrations reported for various species of birds in India. Accumulation pattern of organochlorine pesticides in birds was, in general, in the order HCH > DDT > heptachlor epoxide > dieldrin. Among various pesticides analyzed, p,p'-DDE and β-HCH contributed maximum towards the total OCPs and study indicates the continuous use of lindane and DDT for agriculture and public health purpose, respectively. Although no serious threat is posed by any of the organochlorine pesticides detected in the present study species, continued monitoring is recommended.

Organochlorine residues in blood of cinereous vultures and Eurasian griffon vultures in a northeastern Mediterranean area of nature conservation

In the National Park of Dadia-Lefkimi-Soufli Forest (Dadia NP, Greece), seven "target" PCBs and 16 organochlorine pesticides (OCs) were analysed in blood samples of cinereous vultures (Aegypius monachus) and Eurasian griffon vultures (Gyps fulvus). PCB congeners 138, 153 and 180 predominated in both species' blood samples. In both species, no differences were detected in congener levels between successive age classes, but in cinereous vulture, there were significant differences between adult and nestling in levels of PCB 28, 52, 101, 118 and between nestling and immature in levels of PCB 101. Regarding pesticides, p,p'-DDE dominated in both vultures followed by β-HCH, lindane and endosulfan sulphate, but ∑OCs were higher in griffon vulture. Significant differences were detected only between nestling and sub-adult cinereous vultures in heptachlor levels and between nestling and adult in p,p'-DDT. The origin of pollutants differs between the two vulture species and pollution patterns may not reflect those at Dadia NP.

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 (β-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.

Diclofenac residues in blood plasma and tissues of vultures collected from Ahmedabad, India

The study reports residues of diclofenac, a non-steroidal anti inflammatory drug, in tissues of 11 White-backed Vulture, Gyps bengalensis collected between 2005 and 2007 and blood plasma of 12 White-backed Vulture, four Egyptian Vulture, Neophron percnopterus and two Griffon Vulture, Gyps fulvus collected during 2005. Samples were analysed using High Performance Liquid Chromatograhy (HPLC) equipped with UV detector. One of the White-backed Vultures collected during 2005 had substantial urate deposits on its viscera and diclofenac was detected in its liver (1.42 ppm wet weight) and kidney (1.18 ppm wet weight), which is suggestive of diclofenac exposure and intoxication. Although uric acid crystals were not observed in the remaining birds received during 2005, the residues of diclofenac detected were at levels higher than the toxic limits (0.25-1 ppm). No residues were detected in any of the tissues of birds collected during 2006 and 2007 (6 birds). About 89% (16 of 18) of plasma samples collected during 2005 had diclofenac residues (White-backed vulture: BDL to 0.17 ppm; Egyptian vulture: BDL to 0.09 ppm; Griffon vulture: 0.07-0.14 ppm). However, plasma diclofenac concentrations were less than the concentrations reported to be toxic. Although use of diclofenac for treating cattle has been banned in India, regular monitoring is recommended to assess the effectiveness of the ban on the drug in support of the conservation of these species.

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.