In this TED talk marine biologist Stephen Palumbi explains how putting things into the bottom of the food chain – mercury from burning coal, PCBs (polychlorinated biphenyl – a molecule widely used in industrial applications that causes cancer in humans and animals), lead and dioxins – causes repercussions felt all the way to the top. Palumbi is the author of The Extreme Life of the Sea, reviewed yesterday.
PCBs accumulate in plankton, which are eaten by small fish (or directly by whales). Small fish are eaten by bigger fish, and so on – with PCBs building up at each step. This is called bioaccumulation.
Whales, dolphins, and bluefin tuna, for example, build up heavy metals and PCBs in their flesh which is toxic and often unsuitable for human consumption (hello, Japan). Carl Safina gives a personal example of this on his blog. The same is true of shark meat. Indigenous people in the Arctic, feeding off seals and whales, also build up these chemicals in their bodies and pass it on to their babies in breastmilk. Palumbi gives an example of a dolphin population in a bay off Texas, swimming in a sea of PCBs. Their mothers’ milk is so toxic that 60-80% of the firstborn calves die as a result of being fed by their mothers and having most of her chemical load transmitted this way.
This is a disturbing look at how – to put it delicately – polluting the ocean comes back to bite us on the backside, with direct and measurable impacts to human health.
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