mason@tmsoft.uucp (Dave Mason) (09/06/89)
In article <8328@looking.on.ca> brad@looking.on.ca (Brad Templeton) writes: >Are PCBs that dangerous? I have read that they are quite inert -- that's >why they were used in transformers. According to what I heard, they are >only dangerous if burned improperly, upon which they are carcinogenic. > >Seems to me there are a tremendous number of substances far more dangerous >than that, or have I heard wrong? In article <28908@watmath.waterloo.edu> sccowan@watmsg.waterloo.edu (S. Crispin Cowan) writes: >They are massively carcinogenic on contact. They have on 'no effect >level', i.e. concentrations in the body so small that they are hard to >detect (parts per billion) still seem to statisticly induce cancer. On >the other hand, the "PCBs" being discussed are really PCB-laden oils, >not just pure PCBs. In article <261@van-bc.UUCP> sl@van-bc.UUCP (Stuart Lynne) writes: >Just the other day I heard some (obviously ill-advised) commentator say that >there was no evidence for carcingenic effects other than studies on mice. >And that there where no recorded deaths from PCB's. He did reference a >Japanese study where some workers exposed to PCB's had a skin >dis-colouration. A major article in the Toronto Star Sept 2 quotes prominent scientists such as John Polanyi (recent Nobel in Chemistry), Emmanuel Farber (an authority on toxicology) and Friends of the Earth representative Kai Millyard. Some excerpts: Polanyi: "We have abandoned perspective in the assessment of risks." He suggests that the automobile is a far more dangerous element. Farber: "People have the perception of the worst (but) PCBs by themselves are very low in potency. You would need a large exposure over years (to have any harmful effect). [...] I can't say PCBs are safe or not safe. I *can* say that on the basis of long observation they are *probably* safe. That's the hardest thing to communicate, because it's not emotional." There are 209 different varieties of PCBs...Recent research indicates that, except for sometimes causing skin rashes, most PCBs are virtually harmless to human beings. The varietys with the most chlorine atoms attached are considered capable of causing some cancers in laboratory animals if exposure is heavy and prolonged. But those varieties always were a miniscule part of the PCB mixtures supplied to the electrical industry. That could explain study results on 2500 U.S. workers in electrical equipment factories, who had their hands in PCBs every day, some of them for as long as 35 years. These people, despite the greatest PCB exposure ever recorded, showed no more cancer than in the general public. In one plant, the cancer level was below the national average. Canadian-born Steven Safe, now at Texas A&M, has been researching PCBs for 20 years says: "In cancer, the bottom line is death, and there is no increase (in deaths among humans, from PCB exposure, anywhere)." He also showed that PCBs can reduce the risk of cancer from similar chemicals: furans and dioxins. Kai Millyard: "They're not the most toxic chemicals around. They have moderate toxicity. But the fact they persist so long, and store up in fatty tissues, make even that moderate toxicity a more serious problem." A report to be presented to the American Chemical Society this week will indicate that anaerobic microbes at the bottom of rivers and lakes devour PCBs giving them a 1/2 life of 5-10 years in these environments. M.A.Hayes, associate professor of pathology at Guelph feels PCBs probably have saved many lives, in two ways: by preventing fires in electrical equipment; and by their andidote action in fighting the effects of furans and dioxins that humans may encounter. The bottom line: The independent New York based American Council on Science and Health has repeatedly argued for more logical priorities in what people worry about. It notes cigarettes kill 50,000 Americans every year, as many Americans as died in the entire Vietnam war. It lists annual deaths in the thousands from alcohol, drugs, untreated high blood pressure, and other causes. For PCBs, it lists the total deaths attributed to them in the U.S. since they went into use 60 years ago: 0 (zero). Note: I made no editorial comments in the above excerpts, and tried to represent the tone of the original article accurately. I consider myself an environmentalist, belong to Pollution Probe, etc. My feeling on the PCB issue basically reflects that of this article: PCBs probably shouldn't be poured on your breakfast cereal, at least not on a regular basis, but they are FAR from the greatest threats to life and liberty in our society! As such we should treat them carefully, and should probably destroy those that remain as expeditiously as possible. ../Dave
sl@van-bc.UUCP (Stuart Lynne) (09/07/89)
In article <1989Sep6.141953.14830@tmsoft.uucp> mason@tmsoft.UUCP (Dave Mason) writes: >In article <8328@looking.on.ca> brad@looking.on.ca (Brad Templeton) writes: >>Are PCBs that dangerous? I have read that they are quite inert -- that's > >In article <28908@watmath.waterloo.edu> sccowan@watmsg.waterloo.edu (S. Crispin Cowan) writes: >>They are massively carcinogenic on contact. They have on 'no effect > > A major article in the Toronto Star Sept 2 quotes prominent scientists >such as John Polanyi (recent Nobel in Chemistry), Emmanuel Farber (an >authority on toxicology) and Friends of the Earth representative Kai Millyard. >Some excerpts: Thank you Dave. Finally someone who has a copy of some sensible comments from prominent researchers has taken the time to type them in. I particularly dislike the media's attempts to "hype" PCB's into a menace far out of proportion to what the fact's would indicate. And it really disturbs me when these comments get propagated onto the net. If more people would take the time to think about what they are posting perhaps we could actually educate ourselves a bit more. Anyhow, once again, a big thank you to Dave Mason for typing in the excerpts from that article. -- Stuart.Lynne@wimsey.bc.ca uunet!van-bc!sl 604-937-7532(voice) 604-939-4768(fax)