Published on August 3rd, 2009 | by Kay Sexton1
Pollution Causes Cancer … in Animals
While there are many conservation issues that regularly top the policy bill, such as destruction of habitat, over-hunting, fisheries collapsing and so on, a new concern has recently emerged through scientific studies. Wildlife cancer. In a report entitled ‘Wildlife cancer: a conservation perspective’ Denise McAloose and Alisa L. Newton provide a range of evidence about pollution linked cancers in a number of species.
San Francisco’s famous (tumour-ridden) sea lions?
A wide range of marine species are developing high levels of cancers and carcinomas that are causally – if not directly – linked to pollution and the dumping or stockpiling of contaminants. As an example, the Marine Mammal Center in Sausalito, California, receives many calls about sea lions being photographed by tourists at San Francisco’s famous Pier 39. The callers mention sea lions that seem crippled or disfigured by tumours and where these animals can be caught and investigated, a high percentage subsequently die of unusual causes: renal failure and/or paralysis. These tumours, which are large enough to be noticed by tourists, are linked to high concentrations of polychlorinated biphenyls (PCBs) in the animals’ bodies. PCBs were widely used in coolants until 2001 when they were banned and the dissected sea lions that die of carcinomas have up to 85% higher levels of PCBs than average.
Other marine creatures particularly at risk are beluga whales and bottom-feeding fish, which are seen to be developing high levels of neoplasia, massy tumours associated with pollutants on the sea bed.
Industrial dumping and personal trash both contribute to contaminant build-up
Marine dumping is the most likely cause of such wide-spread cancer developments. Many sea lions that have cancer are found to have high levels of DDT in their blubber, and this possibly results from DDT dumping on a number of offshore islands, including the UK Channel Islands, in the 1970s, when DDT was outlawed.
Industrial level marine dumping of unwanted or stockpiled chemicals, or the leaching of stockpiled chemicals into marine systems from riverside chemical plants is the most likely cause for most of these cancers. However, hazardous waste levels can easily build up on sea beds or in areas around waste dumps on land, and be conveyed out to sea, simply from landfill.
The disposal of everyday products such as plastic bottles, food cans, detergents, flame retardant materials used in upholstery and even toys and cosmetics can lead to endocrine disruptors being released into the environment, and while one bottle, or one sofa, doesn’t present a problem, dumps that specialise in flattening and burying plastic bottles can lead to massive doses of these disruptors entering the food chain. Endocrine disruptors are chemicals that interfere with the function of an organism’s immune system, resulting, amongst other things, in cancer growth.