PERSISTENT Organic Pollutants or POPs refer to a group of carbon-based, toxic chemical substances that can harm human health, wildlife and the environment. They include some pesticides, industrial chemicals and unintentional by-products of certain industrial processes.
Of the numerous POPs that are prevalent in our environment, twelve of the most persistent, bioaccumulative chemicals have been identified for priority action. They are called the “dirty dozen”. These are Adrin, Mirex, DDT, Dieldrin, Enrin, Heptachlor , Chlordane, Toxaphene, Hexachlorobenzene and Polychlorinated biphenyls (PCBs).
Today, POPs are found almost everywhere - in our food, soil, air and water. They pose a particular hazard because they resist normal processes that break down contaminants and they accumulate in the body fat of people, marine mammals, and other animals and are passed from mother to fetus. Wildlife and humans around the world carry amounts of POPs in their bodies that are at or near levels that can cause injury.
Once released into the environment, POPs stay for a long time. They can accumulate through the food chain, or carried by the wind and water to places where it was not used. DDT for instance, one of the pesticides classified as POPs, has been found in the tissue of emperor penguins in the most remote areas of Antarctica. DDT is used for agricultural crops and for controlling mosquitoes and other insects that carry diseases like malaria and typhus. The fact that it managed to reach Antarctica , which has neither crops nor mosquitoes, is a cause for global concern.
A study, led by Newcastle University's Dr Alan Jamieson, has uncovered the first evidence that POPs have now reached the farthest corners of our earth. Sampling amphipods from the Pacific Ocean's Mariana and Kermadec trenches -- which are over 10 kilometres deep and 7,000 km apart -- the team found extremely high levels of POPs in the organism's fatty tissue. These include polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) which are commonly used as electrical insulators and flame retardants. From the 1930s to when PCBs were banned in the 1970s, the total global production of these chemicals was in the region of 1.3million tonnes.
The authors suggest that the pollutants most likely found their way to the trenches through contaminated plastic debris and dead animals sinking to the bottom of the ocean, where they are then consumed by amphipods and other fauna, which in turn become food for larger fauna still.
Oceans comprise the largest biome on the planet, with the deep ocean operating as a potential sink for pollutants and litter that are discarded into the seas. These pollutants then accumulate through the food chain so that by the time they reach the deep ocean, concentrations are many times higher than in surface waters.
Once it reaches the food chain, the pollutant comes back to us humans. It’s another way of saying, “Ang basurang tinapon mo, babalik sa iyo.”