Killer chlorine
Ever since Rachel Carson's famous expose of pesticides, chlorine and its chemical allies have been on the hit-list of environmentalist.
DDT was banned in 1972, followed by PCBs in 1978. Two decades later, CFCs were sentenced to a phase-out for violating the sacred ozone-space. And now, with the recent US Environmental Protection Agency (EPA) report condemning dioxin as a potential health hazard, the die-hard greens are rooting for a death sentence for the chlorine crowd.
The move to ban all uses of chlorine centres around the theory that some chlorinated compounds masquerade as hormones when ingested, falsifying the chemical signals sent by the body to the sexual organs. These so-called hormonal toxicants are alleged to cause severe sexual problems, including malformed sexual organs, shrivelled penises, and effeminate men and animals.
The allies of the chemical industry contend the anti-chlorine propaganda, which they claim is based on non-peer-reviewed studies, should be dismissed outright. EPA is however is using such arguments to push for a ban on chlorine in all its uses, a demand made by the vociferous Greenpeace, which launched its chlorine campaign in the wake of its antifreon propaganda. The ban would be implemented through the Clean Water Act Reauthorisation. It was in order to fulfil this agenda that EPA initiated the "Dioxin Reassessment Study."
Three years in the making, the 2000-page document concludes that exposure to even small quantities of dioxin -- described as one of the most toxic chemicals regulated by EPA -- may cause cancer, birth defects, learning disabilites, reproductive disorders, and immune system deficiencies.
Not surprisingly, chemical companies immediately sought to downplay the findings. "I don't think the general public faces any particular risk," said J Murray, a spokesperson for the Chemical Manufacturers Association in an article in the Washington Post.
As evidence, they often cite the serious outbreak of cholera when chlorination of water was temporarily stopped in Peru. An editorial in the reputed US journal Science said, "Waterborne diseases cause a lot of deaths each day of 25,000 children in less developed countries. A costly gamble in the US to use means of disinfection less effective than chlorine would be irresponsible."
It further said that "there is reason to hope that EPA will not continue to act like a tool of Greenpeace. A plethora of EPA regulations and unfunded mandates coupled with examples of brutality in enforcing them has cost the EPA support in congress."
In fact, much of the propaganda about chlorine's nefarious character has been orchestrated by Greenpeace. This aggressive green outfit has been accused of spreading news, prematurely, in Asia, Latin America and Europe that EPA is going to ban chlorine. And last fall, Greenpeace activists also organised an anti-chlorine demonstration outside a chlorine plant in Australia.
Chlorine supporters charged that EPA, in collusion with Greenpeace, had been secretly briefing environmental groups on the contents of the report so it can use the information to scare the public and prepare fund-raising and legislative campaigns.
They further claim that none of the EPA findings have been peer-reviewed or published in the scientific literature. "No independent scientist has been able to review the accuracy of the study. Instead, EPA is indulging in science by press release both directly and indirectly through its collaboaration with environmental groups, " says Rogelio Maduro, co-author of the Holes in the Ozone Scare.
A population of human guinea pigs Greenpeace and its allies put take refuge behind the Precautionary Principle, which states that when there is enough reason to believe that a substance or a class of substances may cause harm to health or the environment, it should not be used or produced.
Greenpeace documents often employ the doomsday scenario of ozone destruction an an argument in favour of a total chlorine ban. For instance, the UN Environmental Programme has estimated that current ozone depletion trends will result in 300,000 cases of skin cancer worldwide each year and an unknown number of cases of infectious diseases caused by immune system disorders. Increased UV radiation is also expected to reduce productivity among crops, livestock, and the ocean food chain, leading to deficiencies in the world's food supply.Despite all this evidence, argues Greenpeace, the chemical industry continues to claim that the health threat posed by organochlorine pollution has not yet been proven. "The industry demands the right to continue discharging toxic chemicals until "conclusive proof" of harm to humans is established, one chemical at a time. With what is already known about the hazards of chlorinated chemicals as a class, this position amounts to a call for a grand biological experiment with the world's population as guinea pigs," screams one of its pamphlets.
Furthermore, Greenpeace believes the global threat posed by the "chlorine soup" now present in the environment is too complex to be solved by addressing these chemicals one at a time. "If we wish to preserve the life-sustaining capacity of the planet, the root of the problem -- the production and use of chlorine -- must be phased out," alarms another Greenpeace document.
Not surprisingly, consumer rights groups, egged on by Greenpeace, have latched on to the dioxin document as proof of chlorine's "crime". Last fall, the US Public Interest Research Group (PIRG) launched a campaign to ban the use of dioxin-generating chemicals. "This report confirms that even everyday exposure to dioxin can cause life-threatening health problems," said PIRG environmental attorney Daniel Rosenberg. "Banning dioxin is not only prudent, it's long overdue."
While the EPA's report damned dioxin as an miasmic ogre, it refrained from making any specific recommendations on how to control the chemical. Instead, the agency allowed 120 days for the public to comment on the report before making any recommendations.
US PIRG used the comment period as an opportunity to build support for measures to protect the public from dioxin. It enlisted more than 200 organistions to sign on a letter to EPA Administrator Carol Browner, urging her to cut dioxin emissions by banning the use of chlorine in paper bleaching, and phasing it out in other industrial processes.
State PIRG advocates and citizen members also testified at a series of public hearings held around the country to solicit comments on the report, refuting the testimony of lobbyists hired by dioxin-generating industries. Chemical makers, led by Dow Chemicals, have used their lobbying clout in Capitol Hill to block previous legislative efforts to curtail the use of chlorine. In 1994, the chemical and paper industries fought off such an effort, a US PIRG-backed bill to ban chlorine discharge into the nation's rivers, lakes and waterways.
But despite the industry's efforts to maintain the status quo, chlorine markets are shrinking in the North due to environmental pressures. As evidence condemning chlorine continues to pour in, businesses in most indsutrialised countries are replacing ozone-destroying CFCs, chlorine bleach for pulp and paper and chlorinated solvents for cleaning in the electronics, paints and automotive indsutries with safe substitutes.
With chlorine being branded an environmental bugbear, the chemical industry as a whole has set its sights on the industrialising regions of Asia and Latin America, where industry executives forecast major growth for chlorine. Gradually chlorine producers are shifting production to Asian and Latin American countries.
Chlorine makers often justify their product as essential to the health of the Third World because of its usefulness in water disinfection. But water disinfection only accounts for about 1 per cent of chlorine use worldwide. The biggest use of chlorine is in polyvinyl chloride (PVC) plastic.
PVC is associated with dioxin and other organochlorines through out its lifecycle, and is under considerable regulatory attack, especially in Western Europe. A sweeping indictment of PVC comes from the Swedish Ecocycle Commission, a government advisory group, which recently concluded that PVC has no place in the eco-society and recommended its phase out by the year 2000 AD.
Disquieting disclosures
The present report is a more comprehensive sequel to EPA's earlier studies, which date back to the 1980s, on dioxin's nuisance value. In 1991, after intense lobbying by the paper and chemical industries, EPA announced a "scientific reassessment" of the toxicity of dioxin to examine new data on the way dioxin causes health damage. EPA's administrator predicted that the study would result in a lower estimate of dioxin's toxicity and a weakening of dioxin regulatory standards. After three years of study, expert review and public comment, EPA released its assessment in September 1994. Contrary to the industry's intent, EPA's study shows that dioxin poses more of a threat to public health than it was previously thought to pose. EPA's major findings include:
• Dioxin acts like an environmental hormone wreaking havoc on many of the body's natural biochemical processes. When dioxin enters the body it passes through the cell membranes and combines with a natural receptor protein that allows dioxin to enter the cell nucleus. Dioxin then interacts with DNA, turning on genes that control many biochemical reactions, such as the symthesis and metabolism of hormones, enzymes, growth factors, and other chemicals. Like the hormonal signals the body uses to regulate its delicate natural processes, a tiny dose of dioxin cna throw a biological switch, triggering a cascade of events. Unlike natural hormones, however, dioxin resists breakdown within the body. Once the switch has been turned on, it is difficult to turn it off. • Dioxin's most severe effects are on repriduction, child development, and the immune system. Because they are delicately controlled by hormones these processes are susceptible to disruption by tiny doses of dioxin. Exposure during fetal or infant development can lead to hormonal changes, birth defects and reduced growth. More alarming, tiny doses of dioxin can have effects that become obvious only later in life, such as impaired intellectual development, infertility, lowered sperm count, and other reproductive problem at puberty. The immune system is exquisitely sensitive dioxin; very small doses can lead to suppressed immune defenses and increased susceptibility to viral infection. Dioxin has also been linked to the risk of endometriosis, diabetes and other diseases.
• Current levels of dioxin in the bodies of the general human population are already in the range at which health effects are known to occur in laboratory animals, according to EPA. EPA;s findings suggest that dioxin exposure may already be contributing to the society-wide incidence of infertility, cancer, impaired development and other conditions. But the lack of an unexposed control group makes it impossible for scientists to dtermine with certainty whether this is the case.
• EPA has estimated that "background" dioxin exposures result in cancer risk to the general populaton that range from 1 in 1000 to 1 in 10000. This range is from 100 to 1000 times the standard acceptable risk of one per million. Based on EPA's figures, dioxin may be causing 300 to 3500 cancers every year in the US -- upto 3 per cent of all cancers.
But Dioxin is never produced on purpose. It is formed an an accidental by-product in scores of industrial processes that involve chlorine. In fact, dioxin is genrated and released throughout the entire spectrum of chlorine related products and processes. Chlorine is the essential ingredient for dioxin formation.
For example, dioxin is formed when the chemical industry creates chlorine gas in the Chlor-alkali process or when chlorine is used to bleach pulp and paper. When the chemical industry uses chlorine to manufacture such chemicals as plastics, pesticides, and solvents, still more dioxin is formed. Dioxin is even formed when when these chlorinated products are used in hot or reactive situations, such as gasoline additives, wood preservatives, and chemical catalysts. Finally, when any chlorinated waste or product is burned -- in an incinerator or an accidental fire -- large quantitites of dioxin is produced and discharged into the environment.
Curiously enough, with regard to disinfecting water, it acquires a schizophrenic character. It combines with organic matter present in water to produce dioxin or dioxin-like compounds. Usually, however, these toxins are produced in harmless quantities. But add more of it, and you end up with more of poisonous dioxin in your body.
The document represents the most comprehensive effort undertaken yet to identify sources and the major routes of exposure. Airborne deposition seems to be the most prevalent means of transport. The compound then makes its way into the human food chain through ingestion of contaminated plants by animals and deposition of dioxin in fatty tissue. Human exposure through consumption of beef, dairy products, fish, and other food products can result in dose rates that are several times higher than exposure through inhalation, which had been considered the primary route of general exposure in previous assessments.
But some scientists believe EPA is overinterpreting the data, which come mainly from animal studies and observations of clinical disturbances in humans. "I just don't think people have been exposed to enough dioxin to see effects, especially on the immune system," says Oregon State University immunologist Nancy Kerkvliet.
In its indictment of dioxin, however, EPA is including many similar compounds, which agency scientists believe exert similar effects. The underlying assumption is that the dioxin of utmost concern -- 2,3,7,8 TCDD -- exerts its harmful effects by binding to the aryl hydrocarbon (Ah) receptor on the cell surface. Because some PCBs, furans, and other dioxins bind to the same receptor, EPA appraises the risk exposure to these compounds based on their binding affinities.
Some critics of the report argue that this assumption is unwarranted because it fails to take into account how such chemicals might compete for binding sites in some cases or exert a synergistic effect in others.
Even assuming that dioxin and its chemical relatives are as risky as EPA believes, a third area of controversy remains: Just how much of these substances are Americans exposed to? Indeed, FDA has accused EPA of using data gathered mainly in Europe rather than in the US.
Messing up the reproductive system
Much of the debate over chlorine and its relatives has to do with their adverse effect on human reproductive health. And the media has been instrumental in hyping up the role of pollutants in damaging the reproductive systems of humans and wildlife.
The basis for the media hype was a string of research findings in the past few years linking estrogen-like compounds in the environment to events as diverse as a worldwide drop in human sperm counts, a decline in the number of alligators born in Florida lake, and feminised suckerfish in Lake Superior. And it's not just males who are said to be at risk. One widely publicised study, for example, found increased rates of breast cancer among women exposed to estrogen-like pesticides such as DDT. But at least two widely publicised studies suggesting a link between hormone-modulating pollutants and human health risk have recently wilted under the glare of scientific scrutiny. On of these studies tied a global decline in sperm count to pollutants that mimic estrogen, but the timing of the decline is challenged.
In the other study, a team led by Mary Wolff of Mount Sinai Hospital in New York linked breast cancer to high levels of DDE, a breakdown product of the estrogenic pesticide DDT. But in April last year, a research team led by Nancy Krieger of the Kaiser Foundation Research Institute in Oakland, California, failed to confirm the finding.
The chief bone of contention is the relevance of animal studies to human health, and the increased emaphasis by EPA on the noncancer effects of the chemical it regulates. The first is a revival of a perennial debate, but the second is a fresh concern for EPA, which in the past has crafted regulations based mainly on chemical carcinogenicity.
Evidence of this shift in focus can be seen in the agency's deliberations on dioxin. EPA is also planning a major research initiative in 1996 to ferret out the noncancer effects of similar hormonelike pollutants. Lawrence Reiter, director of EPA's health effects research lab in North Carolina, says the threat of hormone modulators may rival pressing global environmental concerns, such as global warming or ozone hole.
Health and hormone modulators
The first evidence that hormone-modulating chemicals could pose a threat to human health came from studies of diethylstilbestrol (DES), a synthetic estrogen that was used to prevent miscarriages for two decades. DES was banned in 1971 after it was linked to a rare vaginal cancer in the daughters of women who took it. The DES prompted researchers to ask whether similar synthetic chemicals in the environment might disrupt fetal development or pose other reproductive threats. Since then, researchers have discovered dozens of chemicals, synthetic and natural, that disturb the endocrine system through the estrogen receptor.
The evidence for this biological activity has come from animal studies involving high levels of exposure to estrogenic pollutants. For instance, female rodents exposed to DDT are likely to develop mammary tumours, while male rodents tend to develop testicular cancer and other reproductive disorders. But are lab exposures relevant to anything we see in the real world? asks John Gierthy, a toxicologist at the New York State Department of Health's Wadsworth Center in Albany.
More persuasive to some researchers are wildlife studies. Some of the strongest evidence from the field comes from research at Florida's Lake Apopka. There, a team led by University of Florida reproductive physiologist Louis Guillete has linked a DDT spill in 1980 to a 90 per cent decline in the birthrate of alligators an possibly to reduced penis size in many of the lake's young alligators. Earlier, researchers had reported on the effects of hormone-modulating pollutants on a range of wildlife, from fewer turtle hatchlings to feminised male birds. Many of the studies have focussed on the Great Lakes, which until recently had high levels of DDT, PCBs, and dioxins.
Researchers have found, for instance, poor reproductive success for bald eagles that consume pollutant-tainted fish from the Great Lakes. In addition, some researchers link PCBs and similar compounds to "Great Lakes embryo mortality, edema, and deformities syndrome" in herring gulls, terns, and other Great Lakes marine birds.
These researchers contend that because the reproductive biology of many of these animals is similar to that of humans, these findings suggest that people exposed to low levels of hormone modulators may be at risk for fertlity problems or even cancer.
But critics make two arguments against a demonstrable link between hormone-modulating pollutants and human health effects. For one, they say, the basic pharmacology doesn't add up. "Most pesticides and other environmental estrogens are only very weak estrogens," says EPA dioxin researcher Linda Birnbaum. Known environmental estrogens bind to estrogen receptor hundreds to thousands of times more weakly than does estradiol. That't true even for men, who convert androgens such as testosterone to estradiol.
Since background levels of synthetic estrogens are swamped by the body's own estradiol, says Rutger's Michael Gallo, there's little chance they would be able to exert an effect. The exception, he suggests, might be cases in which people or wildlife are exposed to massive doses of estrogens, as occurs with lab animals or the Lake Apopka alligators. Besides, humans and other primates also have a mechanism for protecting themselves from estrogens that differs from other mammals, says Neil MacLusky, a researcher in reproductive endocrinology at the University of Toronto Medical School.
A second reason to doubt that environmental estrogens and other hormone modulators pose a threat to human life, says Safe and others, is the acid-base argument. Individually, a strong acid and a strong base might be corrosive. But when mixed the pair often form a benign compound. Similarly, Safe and others argue that a sea of natural and synthetic anti-estrogens may negate any effects of environmental estrogens. Some scientists, however, argue that anti-estrogens can be potent hormone modulators themselves.
Despite sharp disagreements over the potential threat to human health from environmental estrogens like organochlorines, most scientists agree on atleast one point: more research is needed before one can say there's a link between organochlorines and disease. But this sobriety of opinion is not shared by Greenpeace and its allies. For them the die is already cast -- chlorine must go.