Dioxin And PCBs Explained
Gary Ginsberg (Toxicologist) gives expert video advice on: What is 'dioxin'?; How is dioxin dangerous to humans?; How was dioxin discovered to be toxic to humans? and more...
What is 'dioxin'?
Dioxin is one of those boomerang toxins, because dioxin is something that we have generated actually since the cavemen days. It actually comes from fires but it is increased, and we've increased its production by burning plastic or anything with chlorine in it. So dioxin is what we think of as an environmental hormone. It is probably the most potent carcinogen that we know about and it is toxic in many other ways. So the less exposure to dioxin the better.
How is dioxin dangerous to humans?
What dioxin does is it gets inside of your cells and it affects the way the DNA is read out. So that a cell that normally is liver and should be making liver proteins and having liver functions, when the dioxin gets in there it may change the way that cell functions, perturbing it, making it turn more into a cancer cell or making it have other functions that are unnatural. Making it have altered hormone status. So dioxin is a very dangerous chemical, it's sort of a trickster in terms of tricking the cell's DNA to do things it wasn't meant to do.
How was dioxin discovered to be toxic to humans?
Dioxin has been studied in animals and we found that incredibly low doses of dioxin in the parts per trillion level were able to actually kill certain species of animals. I mean, these are levels when they talk about one grain of sand on a whole beach being unimportant, how could something that is that small a quantity be toxic? Well, dioxin is very toxic to certain species. And, so those kinds of findings toxicologists said, "wow, what is going on with this chemical?" So, it led to intense study of what this chemical can do and we found that not every species is equally susceptible but humans are sort of in the middle of the range of sensitivity to dioxins in terms of the acute wasting effects. You actually waste away from dioxins. We also know that you can be poisoned by dioxin. I believe it was the European leader, they tried to assassinate him by giving him dioxin in his diet. And, it was tiny amounts of dioxin in his food that put him in the hospital, gave him something called chloracne and almost killed him. And, so we know that it can be used in human poisonings and the toxicologists know from the studies that it is amongst the most powerful carcinogens, the most powerful acute toxins making the body just waste away.
What are 'PCBs' and how do they get into our diet?
PCBs are Polychlorinated Biphenyls, and they were made mostly in the 1930s through the 1970s to be put in electrical transformers. They are very heat stable molecules that the utilities found highly useful in electrical transmission. The problem with PCBs is that they often leaked out of these transformers, or were just discarded and put into lagoons and sent out into the environment as sludges, and they ended up in water bodies. So PCBs gets into a water body, and gets bio-accumulated into fish. You can find, it would be very hard for you to find PCBs perhaps in the water column, you may not be able to find very much of it in the sediment, but you can find huge amounts of it in the fish because fish are like a sponge for PCBs, and they soak it up, and it concentrates in their, in the fat of the fish, so that eating certain fish from certain water bodies can be a large risk of PCB exposure.
What is 'sludge'?
When we talk about sludge from industries, that's waste material that may come out with a variety of oils and waste materials that often are highly contaminated with things like PCBs.
What are 'persistent pesticides'?
Persistent pesticides' are things like DDT, chlordane. Things that may be, right now, aren't hot button issues, but they were 20, 30 years ago. As a matter of fact, one of the most famous books in environmental toxicology; "Silent Spring" was written exactly about DDT. Why was Rachel Carson writing about a silent spring? The birds were not living anymore because of DDT. It was getting into the earth worms, the birds were eating earth worms, and it was affecting the thickness of the eggshell, they weren't able to reproduce. We know that these kinds of persistent organochlorine pesticides, which are now largely banned, we banned almost all of them, but they're still in our environment because they are so persistent. So, for example, if you applied chlordane around the foundation of your house back in the 1970's, that chlordane is still creating a termite shield around your house, which may be a good thing in terms of keeping termites out of your house, but it's a bad thing in terms of growing any crops, or your children digging or your pets digging in the side yard because that chlordane is so persistent, and it is so toxic that it is a health risk today even though we banned it 30 years ago. These kinds of organochlorine, persistent pesticides can still come at us from the food chain because they cycle through the aquatic environment and do bio accumulate in fish. And I want to add that DDT is still used in certain parts of the world because it is one of the more effective anti-malarial chemicals to kill mosquitoes. And that can come back at us through the fish we eat, and even small amounts can come back into the United States in rainwater.
How are persistent pesticides hazardous to humans?
Persistent pesticides are like the boomerang toxicants that we talked about earlier, in that they do bioaccumulate in the fish or the meat products that we eat, and they do bioaccumulate in us, and they act like environmental hormones, they can disrupt the way estrogens and androgens work in our bodies. So they can affect our success in terms of fertility, they're carcinogens, so if they build up in our bodies that can be a cancer risk, and, since they accumulate in our bodies; we give them to the next generation. So it's important for young girls, especially, to eat lower on the food chain, to have less PCBs -- these chemicals are related to dioxin PCBs -- and it's important early in life to cut down on exposure to these things because we know that the older you get, the higher the levels of these things are in your body. It's important to start early in life, with children's diets, to make sure that they get off to a good start and don't have these accumulative toxicants building up into them, and we don't want them to pass that on to the next generation of children -- your grandchildren. So, again, it's lower on the food chain, and eating the right fish.