Effectiveness of Action in India to Reduce Exposure of Gyps Vultures to the Toxic Veterinary Drug Diclofenac

Abstract

Contamination of their carrion food supply with the non-steroidal anti-inflammatory drug diclofenac has caused rapid population declines across the Indian subcontinent of three species of Gyps vultures endemic to South Asia. The governments of India, Pakistan and Nepal took action in 2006 to prevent the veterinary use of diclofenac on domesticated livestock, the route by which contamination occurs. We analyse data from three surveys of the prevalence and concentration of diclofenac residues in carcasses of domesticated ungulates in India, carried out before and after the implementation of a ban on veterinary use. There was little change in the prevalence and concentration of diclofenac between a survey before the ban and one conducted soon after its implementation, with the percentage of carcasses containing diclofenac in these surveys estimated at 10.8 and 10.7%, respectively. However, both the prevalence and concentration of diclofenac had fallen markedly 7–31 months after the implementation of the ban, with the true prevalence in this third survey estimated at 6.5%. Modelling of the impact of this reduction in diclofenac on the expected rate of decline of the oriental white-backed vulture (Gyps bengalensis) in India indicates that the decline rate has decreased to 40% of the rate before the ban, but is still likely to be rapid (about 18% year−1). Hence, further efforts to remove diclofenac from vulture food are still needed if the future recovery or successful reintroduction of vultures is to be feasible.

Avian scavengers and the threat from veterinary pharmaceuticals

“…Cluster boundaries were selected so that samples from the cluster were available over a period of at least 3 and preferably 5 years to allow estimates of change over time in prevalence and concentration of diclofenac and meloxicam for each cluster. Site-cluster assignments differed from those used previously [18,24] when only the geographical proximity of sampling sites to one another was considered. Details of cluster locations and collection dates are given in the electronic supplementary material, table S1.…”

“…The average proportion of vultures killed per meal, averaged across all meals taken by the vulture population, was then obtained from the probability density function of the dose of diclofenac per unit vulture body weight per meal and the dose-response relationship between diclofenac dose and the proportion of vultures killed. Integration under the curve given by the product of these two functions gives the average proportion of vultures killed per meal [18,24]. Other NSAIDs used were: metamizole (17% of treatments), phenylbutazone (12%), meloxicam (11%), ketoprofen (3%), acetylsalicylic acid (3%) and others ( pitofenone, ibuprofen and flunixin, 2% combined).…”

“…Given that the toxicity of diclofenac to Gyps was reported in 2004 [13], this rapid positive action to halt the decline of Asia's vultures was commendable. However, diclofenac remains a serious threat to vultures in the Indian sub-continent because enforcement of the regulations has been incomplete [24,25] and formulations for humans, in vials that contain a larger quantity of the drug than a human dose, are on sale widely and misused to treat ungulates [26].…”

Merging Wildlife and Environmental Monitoring Approaches with Forensic Principles: Application of Unconventional and Non-Invasive Sampling in Eco- Pharmacovigilance

“…The collection and analysis of tissues from carcasses available to vultures across Asia -to determine compliance with the diclofenac ban and assess the persisting exposure risk from diclofenac and other NSAIDs -is an integral ongoing activity [96][97][98][99]. In a series of widespread surveys undertaken since 2005 across India [94,96,97,99] detectable residues of diclofenac in cow/buffalo carcass liver tissues have been found in 1 in 10 (decreasing to 1 in 20 more recently) samples tested.…”

Sources, factors, mechanisms and possible solutions to pollutants in marine ecosystems

“…Adverse effects of pharmaceuticals to fish and aquatic life are typically detected in aquatic ecosystems (Grondel et al, 1985;Wishkovsky et al, 1987;Vos et al, 2000;Arukwe, 2001;Jobling et al, 2002Jobling et al, , 2006Cleuvers, 2003Cleuvers, , 2004; Thorpe et al, 2003;Brooks et al, 2003Brooks et al, , 2005Schwaiger et al, 2004;Triebskorn et al, 2004;Hoeger et al, 2005;Flippin et al, 2007;Oaks et al, 2004;Caminada et al, 2006;Cunningham et al, 2006;Fent et al, 2006;Filby et al, 2007;Flippin et al, 2007;Johnston et al, 2007;Kim et al, 2007;Owen et al, 2007;Runnalls et al, 2007;Shved et al, 2008;Christen et al, 2010;Corcoran et al, 2010;Nassef et al, 2010;Santos et al, 2010;Cuthbert et al, 2011). Adverse effects include for instance the production of reactive oxygen species in fish (Gonzalez et al, 1998;Laville et al, 2004;Fent et al, 2006;Mostofa et al, 2013aMostofa et al, , 2013b.…”