Full Circle: Drugs, the environment and our health

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Since the mid-1990s, news headlines about “drugs in the water” have alerted the public to an unsettling public health risk. Trace amounts of pharmaceuticals have been detected in Canada’s lakes, rivers, streams and tap water. Other chemicals from food and drug products—including food additives and the ingredients of personal care products, such as shampoos and perfumes—have also been detected, as have veterinary and agricultural chemicals. New biologics, genetic therapies and genetically modified foods are more recent-comers that could end up in this “chemical soup.” As analytic methods for detection are developed, the number of drugs identified worldwide has grown, rising from 20 in 1998 to more than 200 in 2008.

At Women and Health Protection, we look at this neglected form of environmental contamination from a public health perspective, with particular attention to its impact on women’s health.

Women, health products and environmental pollution

Ecosystem contamination with pharmaceutical and personal care products (PPCPs) has the potential to affect flora and fauna, fish and fowl, women and men. However, there are some ways in which women are particularly affected by PPCPs.

Biologically, women have different vulnerabilities to chemicals than men at certain points in the life cycle. Pregnancy is the most obvious example. The diethylstilbestrol (DES) and thalidomide tragedies shattered the long-held rule of toxicology that “the dose makes the poison.” Minute quantities of a drug taken by a pregnant woman at a particular stage in fetal development can cause deformities, cancer and subtle cognitive effects. DES is now recognized as a member of a class of chemicals that disrupt the endocrine (hormonal) system. Some specialists, including Dr. Theo Colburn, author of Our Stolen Future, believe no dose of synthetic hormones is safe for the developing embryo and fetus. Emerging research on endocrine disruptors suggests the male fetus may be more sensitive than the female fetus to many effects of these chemicals (Canadian Partnership for Children’s Health and the Environment 2007). Indeed, epidemiological studies show a small but steady reduction in the proportion of boys born in Japan and the United States over the past four decades. Evidence that the “missing boys” phenomenon is the result, in part, of in utero exposure to endocrine disrupting chemicals comes from communities where chemical exposures are exceptionally high. A 1976 explosion of dioxin from a chemical plant in Seveso, Italy was followed by an immediate loss of males: 46 females and 28 males were born in the next seven years. The First Nations community of Aamjiwnaang, situated in Sarnia, Ontario, the heart of Canada’s petrochemical refining industry, has shown a startling 40% decline in the ratio of males to females over more than a decade.

Abby C. Collier, a pharmacologist at the University of Hawaii, used published dose-response data and clinical prescribing guidelines to estimate the risk that pharmaceuticals commonly identified in drinking water might pose to pregnant women and children. She analyzed 26 pharmaceuticals found in measurable quantities in various studies of drinking water systems and estimated cumulative drinking water exposures for these vulnerable populations. She concluded that five drugs were of greatest concern for pregnant women: ethinyl estradiol (a synthetic estrogen), norethindrone (a contraceptive), diazepam (a tranquilizer), invermectin (widely used for parasite control in livestock), and the NSAIDs ibuprofen and diclofenac (anti-inflammatory agents). She ranked these same five drugs, plus the anti-cancer drug methotrexate, as the substances of greatest concern for the pediatric population, with the safety of an additional four not yet established.

Based on her calculations, a pregnant woman drinking two litres of water per day would ingest 13% of a minimum dose of ethinyl estradiol over a nine month pregnancy, approximately 1.5% of a minimum clinical dose of norethindrone, and almost 5% of a minimum clinical dose of diazepam. For invermectin, ibuprofen and diclofenac, the estimated percentages of a minimum clinical dose were 4%, 3% and 2% respectively. Despite their low levels compared to clinical usage, Collier expressed concern about exposures to these drugs since they may not show linear dose-response relationships when causing birth defects. “Because drinking water is considered healthy and positive in pregnancy, exposure of pregnant women to these five drugs through drinking water is a public health concern,” she concludes. As noted earlier, drugs in combination may interact so that estimated exposures to individual substances don’t tell the whole story.

To date, research on the effects of chemical exposures to the developing fetus and to young children has focused on environmental toxins such as pesticides, dioxins, lead, arsenic and mercury. Evidence is mounting that these exposures affect both boys and girls, but the health effects manifest differently in the two sexes. Boys are at greater risk for cancer, asthma, learning disorders, certain birth defects and testicular dysgenesis syndrome. Girls are at greater risk for premature puberty, which is associated with a variety of psychopathologies in adolescence, including depression, eating disorders, early sexual activity, and early drug abuse, cigarette smoking and alcohol use. Early puberty in girls is also associated with a higher risk of breast cancer later in life. At present, there is a lack of research to specifically link these trends with pharmaceuticals in the environment. However, as Danish researchers Sven Erik Jørgensen and Bent Halling-Sørensen argue, drugs are “in principle not different from other chemicals” so “to distinguish between drugs and other chemicals when they are discharged into the environment is preposterous.”

Chemical contamination of breast milk is another women’s health issue linked to environmental contamination. Aromatic amines—used to make pharmaceuticals, dyes, plastic foams, and pesticides—have been detected in human milk and are known to cause cancer in mammary rat tissue.

Pregnancy and lactation are not the only windows of vulnerability in a woman’s life cycle. Puberty, menstruation and menopause are all the result of hormonal fluctuations. The cells in women’s breasts appear to reach full maturity only at a first full-term pregnancy, when they become more resistant to cancer-causing chemicals and radiation. Women of any age who have not had children may therefore have increased susceptibility to carcinogenic chemicals in the environment compared to women of the same age and health status who have had children. Furthermore, women have more fatty tissue, on average, than men so store more endocrine disruptors in their bodies. Women also have adverse reactions to drugs more often. This difference is only in part because women use more drugs than men and tend to weigh less. A report by the US General Accounting Office concludes, “Greater health risks for women may be due to physiological differences that make women differentially more susceptible to some drug-related health risks.”

Another consideration is that older women have had more years to absorb bio-accumulative drugs from the environment and reduced immunity could make them more sensitive to some effects of environmental chemicals in the water.

Health protection policies should be designed to protect all members of society, especially the most vulnerable. Despite the evidence of the particular damage chemicals can have on women’s health, safety standards for chemicals have often been based on healthy white adult males.

Sharon Batt is a doctoral candidate in bioethics at Dalhousie University. A founder of Breast Cancer Action Montreal and author of the book Patient No More: the Politics of Breast Cancer, she has many years of activism in the areas of breast cancer and environmental health.

This article is an excerpt adapted from a chapter in the forthcoming book, The Push to Prescribe: Women and Canadian Drug Policy, edited by Anne Rochon Ford and Diane Saibil. The Push to Prescribe is a compilation of 10 years of work by Women and Health Protection on women's health, pharmaceuticals and Canadian drug policy. The book will be published by Women’s Press in the fall of 2009.

Endocrine disruptor - Dr. Theo Colborn, author of Our Stolen Future defines an endocrine disruptor as "a compound that interferes with the production, release, transport, metabolism, binding action and /or elimination of hormones in the body."

Bio-accumulative - Toxic chemicals are isolated and stored in fatty tissue of living organisms. These toxins accumulate exponentially as they move up the food chain. Much like the greenhouse "effect" this is known as a bioaccumulative "effect" (i.e., the end product of many chemicals interacting).

The EVRA Patch: A Closer Look at One Product and its Impact on the Environment

Evra, a birth control patch that transfers hormones through the skin, was approved for use in Canada in 2002. It is promoted for its convenience. The patch is no more effective than birth control pills in preventing pregnancy and it has more side effects, including an increased risk of blood clots. Each patch contains 6 mg of norelgestromin and 0.6 mg of ethinyl estradiol. Users are instructed to replace the patch after seven days. At that point, the patch still contains over 80% of the norelgestromin and over 75% of the ethinyl estradiol. According to Janssen-Ortho, the manufacturer of the patch, this high level of waste is necessary to ensure that adequate amounts of the hormones are absorbed. The large amount of synthetic hormone remaining in the patch when it is discarded has been found to feminize male fish. The hormone is one which is persistent—it does not break down over time.

If the patch is folded in half and discarded with other household waste, as recommended by the manufacturer, the residual hormone may well find its way into the ecosystem and pollute our waterways. In Europe, the patch is distributed with its own disposal pouch. While this still doesn't guarantee that the hormones won't eventually leak out into the environment, it does illustrate an important point: disposal instructions are not based on what's good for the global ecosystem, but rather on what's required in each regulatory environment.

The impact that the disposal of drugs has on the environment is the responsibility of environment ministries, mostly at the provincial level. The actual disposal of hazardous drugs by individual households is the responsibility of municipal waste systems. Licensed medical/hazardous waste disposal companies dispose of drugs from pharmacy take-back programs. This multi-level, multi-ministerial, public/private sector shared responsibility has created a jurisdictional gridlock. Unfortunately most prescription drugs, including those containing synthetic hormones that are known to be endocrine disruptors, are not classified as hazardous waste.

While the Canadian Environmental Protection Act (CEPA), passed in 1988 and revised in 1999 and administered by Environment Canada, does have a set of regulations intended to protect Canada’s environment by preventing pollution, these regulations were designed with industrial chemicals in mind. A project to develop regulations under the Food and Drugs Act, which Health Canada administers, has been in bureaucratic limbo since September 2001. Until Health Canada’s Environmental Impact Initiative is completed, CEPA regulations do apply to Evra or to other pharmaceutical products. The case of Evra suggests, however, that pharmaceutical products are not currently being restricted on the basis of environmental harm.

Every opportunity for a pharmaceutical chemical to leach into the water table allows a discharge into the natural environment. Although we are only beginning to understand the bio-accumulative effect that these chemicals can have on the health of the ecosystem, the little we do know is enough to say that any discharge is unacceptable. We cannot control what happens once a chemical has been discharged into the ecosystem. Where we do have control is in reducing use.

In the case of the residual hormone contained in the Evra patch, we can, with education and regulation, discourage use of the patch for convenience and, if use is medically indicated, encourage the safest possible disposal.

-Adapted from a paper published by Women and Health Protection, originally written by Suzanne Elston in 2004.