The short answer: probably not. For a drug to be approved for human or animal use, toxicity research must be conducted (although these requirements vary by country, read more about how drugs are approved in Canada10 and how drugs are approved in the USA11). Unfortunately, potential ecosystem toxicity (ecotoxicity) is not often at the forefront of the drug-approval process. Even if ecotoxicity studies were performed with diclofenac, it is unlikely that the toxicity to vultures would have been discovered before drug approval, as vultures are not a common test animal used in these types of studies. Only a full chemical assessment with ecosystem modelling and subsequent toxicity tests could have predicted the toxicity to the vultures; but these tests are expensive, time consuming, and not the norm during the current drug-approval process.
Currently, meloxicam has replaced diclofenac as an NSAID for livestock in India. Both drugs have a similar mechanism of action in the treatment of inflammation; however, unlike diclofenac, meloxicam is rapidly metabolized and excreted by vultures. In a study where different vulture species were administered meloxicam, researchers observed the production of three metabolites identical to those observed in humans during clinical trials.12 Vultures have the enzymes required for the metabolism of meloxicam (specifically cytochrome P450s and glucuronide transferase). The formation of metabolites alters the biological activity of meloxicam, increasing its water solubility and allowing for faster renal excretion.
The Indian Vulture Crisis: An Example of Complex Systems BehaviorThe \"Indian Vulture Crisis\" may or not be a familiar term to you, but it is important enough to the history of modern India that it has involved dozens of research experts as well as major changes in wildlife, human health, and government policies, and now has its own Wikipedia page (Indian vulture crisis) that you can browse. It is also an interesting example of complex systems behavior that involves food systems and unintended consequences of veterinary care for animals. The main causal links are outlined below in figure 1.2.2, and the narrative of the crisis goes as follows:
Beef cattle are hugely important to Indian food systems even though they are usually not consumed by adherents of the majority Hindu religion (however, Indian Christians and Muslims, for example, do consume beef). Cattle are also widely used as dairy animals (think: yogurt and clarified butter as important parts of Indian cuisine) and are even more important as traction animals (oxen) to till soil for all-important food crops by small-scale farmers across India. Because of their importance and to treat inflammation and fevers in cattle, in the 1990s the drug diclofenac was put into widespread use across India. However, timed with the release of this medication, a precipitous drop in the population of Indian vultures began, which became the fastest collapse of a bird population ever recorded. Vultures are not valued in many parts of the world, but scavenging by vultures was the main way that dead animal carcasses were cleared from Indian communities, especially in the case of beef cattle where the meat is not consumed. It was not until the 2000s that the cause of vulture population collapse was discovered to be the diclofenac medicine administered to cattle, which is extremely toxic to vultures eating dead carcasses. However, the consequences of this population collapse did not end with the solving of the mystery of the vulture population collapse, which was already a tragic and unforeseen consequence. Rather, the fact that vultures are a key part of a complex system resulted in further unforeseen consequences in both human and natural parts of the Indian food system. A few of these are shown in figure 1.2.2 below: first, since vultures are in fact an ideal scavenger that creates a \"dead end\" for human pathogens in rotting carcasses, and since they were no longer present, water supplies suffered greater contamination from carcasses that took months instead of weeks to rot, leading to greater human illness. Second, populations of rats and dogs, which are less effective carcass scavengers, expanded in response to these carcasses and the lack of competition from vultures, which resulted in dramatic increases in rabies (and other diseases) due to larger dog and rat populations and human contact with wild dogs. This is significant since more than half of the world's human rabies deaths occur in India. Finally, the vulture crisis even had implications for religious rituals in India: people of the Parsi faith, who practice an open air \"sky burial\" of their dead where the body is consumed by vultures, were forced to abandon the practice because of hygiene concerns when human bodies took months instead of weeks to decompose. A final consequence of these problems was that the drug diclofenac was banned from use in India, Nepal, and Pakistan in hopes of helping vulture populations to revive. This final turn of events is an example of the human system responding to the unforeseen consequences. Additionally, alternatives to these drugs have been developed for veterinary use that have no toxicity to vultures.
Note the properties of complex systems and human-natural systems exhibited by this example. Farmers sought mainly to protect their cattle from inflammation and speed healing in service of the food system, while pharmaceutical companies sought to profit from a widespread market for an effective medication. The additional, cascading effects of the human invention diclofenac, however, were dramatic, far-ranging, and in some cases unexpected, because of the many interacting parts in the food systems and ecosystems of Indian rural areas: cattle, groundwater, wild dogs, and human pathogens like rabies. The crisis eventually provoked responses from the human system, with impacts on human burial practices among the Parsi, laws banning diclofenac, and development of alternative medications. The search for sustainability in food systems, like those you will think about for your capstone regions, involves designing and choosing adequate human responses to complex system behavior.
One final note on this example is to point out that to fully understand the Indian vulture crisis a large number of different disciplines were brought to bear: we need cultural knowledge about the beliefs and practical usefulness of both cattle and vultures in India. We also need biological knowledge about drug toxicity to wildlife, pathogens, groundwater contamination by microbes, and rat and dog populations. We also need policy expertise to think about transitioning food systems to less toxic alternatives to current practices. And all of these disciplines needed to be brought together in an integrated whole to assemble the diagram shown in figure 1.2.2. The purpose of this text and this course on food systems is to help you to develop some of the skills needed for this sort of interdisciplinary analysis of human-environment or human-natural systems. Previous Page Next Page
When the connection was made between the widespread use of diclofenac and the vulture population decline, India became the first country to argue for a ban on veterinary diclofenac in 2005. By 2006 a complete phaseout of the drug in Nepal and India had begun. (Pakistan later joined this ban.) While the ban was interpreted by many authorities as a positive sign for vultures, in many areas it did not prevent ranchers from purchasing the remaining supply of diclofenac from store shelves and continuing to use it. Many ornithologists and wildlife managers fear that some or all of the species will go extinct before the last course of the drug is used. What makes matters worse is that some ranchers are obtaining prescriptions for diclofenac intended for humans from their own doctors and administering it to their livestock.
The largest section of the book is devoted to a compendium of information on each bird, including fine illustrations, natural history, and the (often dramatic) reasons why the species is threatened. Sadly, the causes are too often human: everything from global warming to habitat destruction is causing some very rare, charming, and even useful birds to die out; some of them have not been sighted in decades, and some exist only in captivity. Three of the species are the Asian vultures affected by the use of the livestock medicine diclofenac in India, Nepal, and Pakistan: Gyps bengalensis (white-rumped vulture), G. indicus (Indian vulture), and G. tenuirostris (slender-billed vulture).
Hooded vultures have declined by more than 50 percent in the last 50 years and are currently faced with numerous threats, most related to human persecution, including hunting for food, use in witchcraft, incidental poisoning and poisoning by poachers.
The policy choices we make now and as we start to emerge from the health emergency will shape whether private equity gains a stronger foothold in residential real estate. A more powerful group of Wall Street landlords that hold sway over even more families would worsen the affordable housing crisis. We should stand up against a private equity takeover and instead advance towards secure affordable housing for all.
Beyond those concerned with conservation, few mourned the passing of the vultures. Like with most creatures, humans have a schizophrenic relationship with vultures. In India, it is worshipped as Jatayu, the vulture god of the epic Ramayana who died protecting goddess Sita. When the demon king Ravana was forcibly flying away with Sita, Jatayu tried to stop him but was overpowered by Ravana, who chopped off his wings. Yet, vultures have always been viewed with distaste and associated with morbidity as harbingers of death. In common lexicon, a vulture has negative connotations, used as a metaphor to describe someone who preys on the weak or benefits from the misfortune of others. 153554b96e