DICLOFENAC: A NEW ENVIRONMENTAL POISON IN SOUTH ASIA

摘要

The rapid collapse over the past decade of populations of three species of Gyps vultures in South Asia has relatively few near-precedents in Natural History, all of which followed the appearance of a novel disease factor or of a new environmental chemical. Local population declines of White-backed (Gyps bengalensis) and Long-billed Vultures (Gyps indicus) were documented at the southern peripheries of their ranges in the 1970s and 1980s, but a reduction in the number of nesting pairs of White-backedVultures and a pattern of unusual mortalities were first observed in Keoladeo National Park during the 1996-97 nesting season. Diclofenac, a non-steroidal anti-inflammatory drug (NSAID) that has since 1994 come into widespread use as a veterinary medicine throughout South Asia, is now considered to be the principal cause of the mortalities associated with the population declines, with possible contributions of other NS AIDs. It is particularly toxic to White-backed Vultures and at least three other species of the genus Gyps. In India diclofenac has been widely used as a veterinary medicine in a minimum of 48 formulations produced by a minimum of 27 companies, accounting for two thirds of the NSAID veterinary market in 2003. Two other NS AIDs recommended for use as veterinary medicines in India, ibuprofen and phenylbutazone, have demonstrated toxicity to vultures; others have not yet been tested, including analgin which was formerly in widespread use before the introduction of diclofenac. In 2006, thegovernments of India, Pakistan and Nepal ended the manufacturing, importation and registration of diclofenac as a veterinary medicine; meloxicam, an NSAID shown to be relatively non-toxic to vultures, is the recommended replacement. As existing suppliesof diclofenac are still being used, because its human use continues, and because other drugs in use are toxic to vultures, it is highly unlikely that the continuing rapid rate of population decline can be reversed before two of the species are extinct inthe wild in the Subcontinent or before significant components of genetic diversity are lost. Only the immediate shelter in captivity of a number of each of the species that will assure the preservation of adequate genetic diversity will permit their long-term survival and eventual reintroduction to the skies of the Subcontinent.