Policy Documents

Instant Expert Guide: Facts about Chlorine and Dioxins

Joseph Bast –
March 1, 2000

1. What Is Chlorine?

Chlorine is an element found in abundance in the natural world. It is one of 118 elements that comprise the matter that makes up our universe, and one of the 20 or so that make up 90 percent of our planet. It is found in nature as inorganic salts (common table salt is sodium chloride) and in more than 1,500 organic compounds, including plants, animals, and even human blood and saliva.

Chlorine is extensively used in manufacturing processes and as part of finished products. It is the feedstock for many types of plastics, including polyvinyl chloride, or PVC, the material used for everything from packaging and toys to siding for homes. Chlorine is used to disinfect 98 percent of potable water supplies in the U.S. It is a key ingredient in approximately 85 percent of medicines and pharmaceuticals, including many commonly used cold remedies and vitamins. Nearly all crop protection chemicals (herbicides and pesticides) use chlorine in their production.

2. What Are Dioxins?

Dioxins are a family of some 75 different compounds and 135 related compounds called furans. One particular form of dioxin, 2,3,7,8-TCDD, is extremely toxic to laboratory animals and, at sufficiently high doses, poses a threat to human health as well. "Dioxin" and TCDD are often used synonymously, and the toxicity of other dioxins and furans is usually expressed in terms of their TCDD equivalencies.

Dioxins are part of the chlorine debate because they contain chlorine atoms. Dioxins are created in small amounts when chlorine is present during naturally occurring combustion (forest fires, volcanoes) or combustion resulting from human action (motor vehicles, metals production, electricity generation, wood-burning fireplaces, etc.). Under certain conditions, dioxins can be formed when chlorine is used in industrial processes, but dioxin emissions from those processes have declined dramatically in recent years.

3. Why Is Chlorine Under Attack?

Greenpeace, a radical environmental group best known for its "save the whales" antics, has been waging a noisy campaign to ban commercial uses of chlorine. Their reasoning goes as follows:

  • Tests conducted on rats and guinea pigs show dioxins to be the most potent animal carcinogens (cancer-causing chemicals) known to man.
  • Nearly all of the dioxins that currently exist were produced by human activities, not by natural processes. Because they are "unnatural," dioxins pose a unique threat to living organisms.
  • We can infer from the effects of dioxins on laboratory animals that all chlorinated compounds pose a threat to human and ecological health.
  • Continued use of chlorine makes injury to human health inevitable given the toxicity and longevity of chlorinated compounds; their unavoidable release during manufacture, use, or eventual incineration; and their link to the formation of dioxin. The only remedy is zero emissions: a complete ban on the commercial use of chlorine.

4. What Do Scientists Say?

While Greenpeace and its allies get plenty of sympathetic coverage in the mainstream media, they have very little support among mainstream scientists. In August 1994, the editors of Regulatory Toxicology and Pharmacology published a special issue containing a 1,000-page report on chlorine written by a panel of independent scholars. It concludes:

"(i) The presence of chlorine in a molecule does not necessarily confer unique toxic properties or bioaccumulative potential;

"(ii) Chlorinated chemicals span a wide range of physical/chemical properties and molecular structures, consequently display a wide range of environmental fate characteristics and biological activities, and thus cannot be considered as a single group for the purposes of health or environmental risk assessment;

"(iii) Chlorinated organic chemicals can persist and bioaccumulate when released into the environment;

"(iv) Many chlorinated chemicals are produced from natural sources and, in some cases, the contribution to ambient concentrations from natural sources exceeds that from human activities; and

"(v) Technological improvements leading to reductions in the formation of chlorine-containing by-products, decreased emissions, and a reduced likelihood of accidental releases are expected to further reduce the concentrations in the ambient environment."

Dioxins are not entirely "unnatural": They have been found in soil, clay, and plant samples dating back to the mid-l800s, long before the rise of the chlorine industry. Large-scale and uncontrolled burning of trash and coal, along with the production and use of leaded gasoline and PCBs (now banned), was probably responsible for the rise in dioxin concentrations in food, air, and water between 1930 and 1970. The source of chlorine in these situations was not plastic products, which didn't exist at the time, but naturally occurring salts.

5. How Dangerous Are Dioxins?

No credible study to date has shown an increased risk of cancer, developmental disorders, or other illnesses attributable to exposure to "background" levels of dioxins or other organochlorines. Until very recently, even scientific studies of people exposed during industrial accidents to extremely high levels of dioxins failed to find any long-term adverse health symptoms. The May 1999 issue of the Journal of the National Cancer Institute, however, reported a study that found a slightly increased rate of some forms of cancer for workers exposed to dioxins at levels 100 to 1000 times higher than the general population. This study, like all epidemiological research, is valid only if its findings are replicated by future researchers.

Dr. Albert C. Kolbye, a former assistant U.S. surgeon general and past president of the International Society of Regulatory Toxicology and Pharmacology, says "for the most part, dioxins et al. are non-problems for the American people and others for the simple reason that human exposures are very low and non-effective in creating damage to human health."

Scientists agree that exposure levels are falling over time. In addition to evidence that concentrations of dioxins in food, water, and sediments had nearly returned to pre-industrial levels by the 1990s, EPA figures show that dioxin emissions from industry declined 75 percent between 1987 and 1995. Due to new regulations, those emissions are expected to decline by another 90 percent in the next few years.

6. Doesn't EPA Say Dioxins Are a Major Health Threat?

Depending on which part of EPA's Web site you visit (in February 2000), you will find reassurance--"While dioxin has been shown to be toxic to certain lab animals, evidence is lacking that it has serious long-term effects on humans," (http://www.epa.gov/rgytgrnj/kids/dioxin.htm)--or reason to be alarmed--"Dioxins have been characterized by EPA as likely to be human carcinogens and are anticipated to increase the risk of cancer at [current] background levels of exposure." (http://www.epa.gov/opptintr/pbt/dioxins.htm)

Those who claim EPA's support for their scaremongering on the dioxin issue usually cite these lines from a 1994 "draft" report on dioxins: "[A] spectrum of effects ... may be occurring in humans at very low levels [of exposure] and some may be resulting in adverse impacts on human health." This statement is inconsistent with the rest of the report, which admits the likelihood of health effects at low levels of exposure "remains uncertain and controversial" and "there is currently no clear indication of increased disease in the general population attributable to dioxin-like compounds."

EPA's 1994 report failed to find sufficient evidence to classify dioxins as a "known cancer hazard." Its claim that human health effects "may be occurring" was inferred from animal studies and not based on human data, and no human data have emerged during the past six years to confirm the inference. EPA's own Science Advisory Board criticized its exaggeration of its findings, as did a group of 18 prominent dioxins experts who signed a letter of protest published by Science magazine.

7. Why Are So Many Environmentalists Wrong About Dioxins?

The dioxin scare began due to a series of errors in thinking:

  • Some scientists and policy advocates assumed humans are just as sensitive to dioxins as are guinea pigs and rats. Only later did it become widely known that humans (and several other species) are thousands of times less sensitive than these laboratory animals.
  • Some scientists and advocates (including EPA in its 1984 report) assumed that if high levels of exposure to dioxins cause health disorders, then exposure to very low background levels of dioxins must cause proportionately less, but still significant, effects. Many scientists now believe this assumption, called the Linear Dose-Response assumption, is false for exposure to trace amounts of most chemicals.
  • When high levels of dioxins were found in or around residential communities, as at Love Canal, New York and Times Beach, Missouri, some advocates assumed the dioxins were responsible for every ailment and health tragedy that occurred in those communities. In fact, correlation is not proof of causation.

The dioxins scare grew because these errors in judgment created an issue ideally suited to exploitation by headline writers, politicians, career environmentalists, and some corporations. Newspapers during the 1970s and 1980s were filled with scary headlines about the supposed threat of dioxins, even though scientific proof was nonexistent. Countless politicians used the Love Canal incident to posture as defenders of human health against heartless chemical companies.

Activists such as Lois Gibbs used the Love Canal episode to launch their careers. Greenpeace, which mailed an astounding 43 million fundraising letters in 1990, became dependent on the dioxin scare for much of its income. Many stores that sell health food and "environment friendly" products spread Greenpeace's untruths in order to sell more of their products.

8. What Is the 'Endocrine-Disrupter Hypothesis"?

The Endocrine-Disrupter Hypothesis is a theory suggesting that exposure to very low concentrations of certain synthetic chemicals may disrupt our endocrine systems, the hormone-secreting networks of glands and organs that regulate our bodies' growth and metabolism from before birth through old age. These chemicals have been called "endocrine disrupters" because they are thought to mimic natural hormones, inhibit the action of hormones, or alter the normal regulatory function of the immune, nervous, and endocrine systems.

The Endocrine-Disrupter Hypothesis was first advanced during the 1970s when diethylstilbestrol (DES), a synthetic estrogen used to prevent miscarriages, was identified as the cause of increased rates of vaginal cancer in the daughters of women who took the drug. Since then, wildlife studies have shown that some chlorinated compounds, such as TCDD, DDT, DDE, and PCBs, have caused reproductive failure and abnormalities in birds and fish.

It is a seemingly small step to speculate that exposure to these chemicals could also be responsible for a variety of health problems allegedly being experienced by the general human population, such as falling sperm counts, increased rates of breast, prostate, and testicular cancer, and birth defects and miscarriages.

9. What Do Scientists Say About That?

The definitive study of the endocrine-disrupter issue was released by the National Academy of Sciences (NAS) in 1999. It confirmed that exposure to a variety of toxic compounds, some of them chlorinated and others not, can cause endocrine disruption among some forms of wildlife. But the NAS found no evidence of human health effects at current levels of exposure. Similarly, EPA in 1997 concluded "with few exceptions (e.g., DES), a causal relationship between exposure to a specific environmental agent and an adverse effect on human health operating via an endocrine disruption mechanism has not been established."

The Endocrine-Disrupter Hypothesis faces four specific hurdles:

  • Many of the trends in human health alleged by advocates of the hypothesis do not exist. Scientific evidence either does not exist or contradicts allegations of falling sperm counts and increased rates of breast cancer, birth defects, and miscarriages. There do appear to be increases in the rates of endometriosis (growth of endometrial cells in aberrant locations, causing infertility, internal bleeding, and pelvic pain) among women and, among men, increases in the rates of prostate and testicular cancer and cryptorchidism (failure of the testes to descend into the scrotum), but both EPA and NAS say those diseases or conditions have not been linked to exposure to synthetic chemicals.
  • The environmental estrogens most often mentioned by environmentalists, such as PCBs and DDT, are very weak compared with the body's own estrogens. For example, DDT is eight million times less potent than estradiol, the primary human estrogen.
  • Our exposure to synthetic estrogens is one million times less than our exposure to natural estrogens that we ingest in many common foods, including soybeans, cabbage, sprouts, and legumes. If our bodies' natural defenses allow us to swim safely in this "sea of estrogen," then there is little basis for assuming they do not also work against synthetic estrogens.
  • Studies of wildlife exposed to synthetic estrogens, often accompanied by other potent toxins such as lead and mercury, are less reliable guides to human health effects than ongoing studies of humans exposed to known doses of specific compounds. Such studies do not show the negative health effects predicted by the Endocrine-Disrupter Hypothesis.

10. Is There a Link Between Chlorine and Breast Cancer?

EPA's 1997 report and the NAS 1999 report surveyed all available literature on a possible link between environmental estrogens and breast cancer and found no evidence to support the claim. The NAS report specifically rules out any association between breast cancer rates and exposure to DDE, DDT, TCDD, endrin, and toxaphene.

Lorenz Rhomberg Ph.D. and Jan Hee Kang S.M., both of the Harvard Center for Risk Analysis, wrote in 1998: "There is no body of evidence showing any consistent association of breast cancer with any such exposures or with body burdens of environmental contaminants."

The largest and latest study of the matter yet, funded by the National Cancer Institute and National Institute of Environmental Health and Safety and performed by researchers at the Yale Cancer Center, "did not find a significant relationship between exposure to PCBs or the pesticide DDE, and the risk of breast cancer in women." This study was released in February 2000.

11. How Much Would it Cost to Phase Out Chlorine?

The best estimate of the cost of phasing out chlorine is $91 billion a year, or more than $1,300 for a typical family of four. This estimate comes from a Charles River Associates study conducted for the Chlorine Chemistry Council. Here are its conclusions in its own words:

Charles River Associates estimates that a ban on chlorine's use would cost U.S. consumers more than $90 billion per year for alternative products and processes. Plant and equipment changes to produce alternatives--with no guarantee of equivalent performance or quality--would cost $60 billion and take up to 20 years. In addition, little is known about potential environmental and health impacts of alternatives.

Nearly a half-million people work for companies that are direct users of chlorine and chlorine- based products, earning a combined payroll of $13.5 billion per year. These figures do not include health care and agriculture, even though both are heavily dependent on chlorine inputs. Banning chlorine would place an enormous burden on these workers and industries.

12. Are There Alternatives to Chlorine?

There are alternatives to every current use of chlorine, but this is the wrong question to ask. The real question is: How much are we willing to give up each time we choose an alternative to chlorine?

Water can be disinfected by treatment with ozone or ultraviolet radiation rather than chlorine, but this fails to disinfect the water in the pipes that bring water to our homes. The increased risk to the public's health outweighs whatever benefit might come from reducing the presence of disinfectant byproducts in drinking water, and it would cost taxpayers tens of billions of dollars nationwide to retool the nation's water treatment facilities. Is it worth it?

Plastics used in autos can be replaced with wood, fabric, and metal, but doing so would add thousands of dollars to the cost of a new car and considerable weight to new vehicles, thereby reducing gas mileage. Using more metal requires more mining, and using more fabric or leather also has ecological consequences. We could go back to wood siding for houses rather than PVC, but this would require logging tens of thousands of additional acres of trees each year. In these instances, the alternatives to chlorine are inferior for consumers and for the environment.

We could stop producing lifesaving drugs or crop protection chemicals (herbicides and pesticides) that require chlorine for their manufacture, and go back to less effective drugs, surgery instead of drug therapy, and deadly though "natural" pesticides such as arsenic, lead, and copper sulfate. The cost to the public in human suffering and premature death, and more expensive health care and less plentiful food, would be immense.

13. What Can I Do?

First, learn more about the chlorine issue by visiting The Heartland Institute's Web site at http://www.heartland.org. Use PolicyBot® to conduct searches for the words "chlorine" and "dioxin." Dozens of free documents on the chlorine debate--including sources for all of the quotations appearing in this "Instant Expert Guide"--are posted there. Or go to your public library and ask for the National Academy of Sciences and EPA studies mentioned earlier.

Second, if you currently give money to Greenpeace, World Wildlife Fund, or Natural Resources Defense Council, challenge them to respond to the evidence presented here. If they can't persuade you that they are right to campaign against chlorine, they don't deserve your continued support.

Third, respond to articles in newspapers and magazines that misrepresent science or fail to present both sides of this issue. Write a letter to the editor or call the reporter. Always be polite and as brief as possible, but make sure they know that the weight of scientific opinion is on chlorine's side.

Fourth, talk to your grocer and the people who own and operate stores in your neighborhood. Tell them that those who campaign against chlorine are abusing and misrepresenting science, and that as a consumer you value the ability to choose superior products made with chlorine.

For more information about The Heartland Institute, chlorine, or to sign up for one of our free electronic newsletters, write to us at:

The Heartland Institute
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