Environmental Problems, Their Causes, and Sustainability 1

chemicals, a little about many, and next to nothingabout most.” The U.S. National Academy of Sciencesestimates that only about 10% of at least 80,000 chemicalsin commercial use have been thoroughly screenedfor toxicity, and only 2% have been adequately testedto determine whether they are carcinogens, teratogens,or mutagens. Hardly any of the chemicals in commercialuse have been screened for possible damage to thehuman nervous, endocrine, and immune systems.Currently, federal and state governments do notregulate about 99.5% of the commercially used chemicalsin the United States. There are several reasons forthis lack of regulation. One is that under existing U.S.laws, most chemicals are considered innocent untilshown to be guilty. Some analysts think this is the oppositeof the way it should be. They ask why chemicalsshould have the same legal rights as people.A second reason is that there are not enoughfunds, personnel, facilities, and test animals availableto provide such information for more than a smallfraction of the many individual chemicals we encounterin our daily lives. A third limitation is that it isdifficult and expensive to analyze the combined effectsof multiple exposures to various chemicals and thepossible interactions of such chemicals.xHOW WOULD YOU VOTE? Should chemicals be regulatedbased on their effects on the nervous, immune, and endocrinesystems? Cast your vote online at http://biology.brookscole.com/miller14.Is Pollution Prevention the Answer?Taking PrecautionsPreliminary but not conclusive evidence that achemical causes significant harm should spurpreventive action, some say.So where does this leave us? We do not know a lotabout the potentially toxic chemicals around us and insideof us, and estimating their effects is very difficult,time consuming, and expensive. Is there a way out ofthis dilemma?Some scientists and health officials, especiallythose in European Union countries, are pushing formuch greater emphasis on pollution prevention. Theysay we should not release into the environment chemicalsthat we know or suspect can cause significantharm. This means looking for harmless or less harmfulsubstitutes for toxic and hazardous chemicals or recyclingthem within production processes so they do notreach the environment.This prevention strategy greatly reduces the expendituresof huge amounts of money on statistically uncertainand controversial toxicity studies and exposurestandards. It also lowers the risk from exposure to potentiallyhazardous chemicals and products and theirpossiblebutpoorlyunderstoodmultipleinteractions.This approach is based on the precautionary principle:When there is plausible but incomplete scientificevidence (frontier science evidence) of significant harmto humans or the environment from a proposed or existingchemical or technology, we should take action toprevent or reduce the risk instead of waiting for moreconclusive (sound or consensus science) evidence. Thisprinciple is based on familiar axioms: “Look beforeyou leap.” “Better safe than sorry.” “An ounce of preventionis worth a pound of cure.”Under this approach, those proposing to introducea new chemical or technology would bear the burdenof establishing its safety. This means two major changesin the way we evaluate risks. First, new chemicals andtechnologies would be assumed harmful until scientificstudies can show otherwise. Second, existing chemicalsand technologies that appear to have a strongchance of causing significant harm would be removedfrom the market until their safety can be established.Some movement is being made in this direction,especially in the European Union. In 2000, negotiatorsagreed to a global treaty that would ban or phase outuse of 12 of the most notorious persistent organic pollutants(POPs), also called the dirty dozen. The list includedDDT and eight other persistent pesticides,PCBs, and dioxins and furans. New chemicals wouldbe added to the list when the harm they cause is seenas outweighing their usefulness. This treaty went intoeffect in 2004.Manufacturers and businesses agree that somechemicals are too dangerous for widespread use andthat some technologies such as coal-burning plantscarry high health risks. But they contend that widespreadapplication of the precautionary principlewould make it too expensive and almost impossible tointroduce any new chemical or technology. Strict applicationof the precautionary principle would stiflechemical and technological innovation and risk taking.We can never have a risk-free society. For example, ifwe had strictly applied the precautionary principlewould we have automobiles, antibiotics, or plastics?On the other hand, proponents of increased relianceon the precautionary principle say that it willencourage innovation in developing less harmful alternativechemicals and technologies and in findingways to prevent as much pollution as possible insteadof relying mostly on pollution control. It is true that wecannot have a risk-free society. But proponents believewe should make greater use of the precautionary principleeffort to reduce many of the risks we face. As youcan see, there are no easy answers for knowing whento apply the precautionary principle.xHOW WOULD YOU VOTE? Should we assume that newchemicals that can end up in the environment are guilty ofcausing harm until proven innocent? Cast your vote online athttp://biology.brookscole.com/miller14.418 CHAPTER 19 Risk, Toxicology, and Human Health