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By Laxmi Murthy Pesticides contaminate every layer of the ecosystem today, causing untold harm to the health of human beings. Persistent organic pollutants have a tendency to accumulate in fatty tissue, making women most vulnerable to toxic contaminants, since women have a higher percentage of body fat, accompanied by regular hormonal changes through the reproductive cycle
The recent furore over whether or not soft drinks manufactured in India by Coca-Cola and PepsiCo contain pesticides has highlighted the contamination of beverages and the lack of regulation of these products. While consumers of soft drinks in India may be paying for their poison, the pollution of groundwater and agricultural products impacts a far larger mass of people: the entire population of the country. Pesticides have entered the natural foodchain, contaminating every layer in the ecosystem. DDT and other chlorinated pesticides like aldrin, endrin, lindane and endosulfan are persistent organic pollutants (POPs) which remain intact and have a tendency to accumulate in fatty tissue. The health hazards for human beings have been well documented: human beings, at the top of the foodchain, are the most vulnerable to the health risks, as ingestion of toxic contaminants is several-fold higher through the process of bio-magnification. Besides the short-term side-effects of pesticide poisoning, like dizziness, blurred vision, vomiting, diarrhoea and stomach cramps, of concern is the long-term health impact in the shape of cancers, disruption in the endocrine, reproductive and immune systems, as well as mutagenicity. Women are particularly vulnerable, as are children who suffer the impact of ‘hand-me-down’ toxins during foetal development and later through breast milk. The storage of toxins in fat is a problem of greater importance in women because of their higher percentage of body fat and the hormonal changes that occur during pregnancy, lactation and menopause, which can result in mobilising internal stores of pollutants many years after initial exposure. Further, an increasing number of chemicals, including DDT, endosulfan and other organochlorine compounds, are being termed ‘xenoestrogens’ -- substances foreign to the human body that directly or indirectly act like the female hormone estrogen. Xenoestrogens or ‘environmental hormones’ are endocrine disruptors, that is they interfere with the normal functioning of the endocrine system -- cells and glands in the body that secrete hormones, the chemical messengers that regulate bodily processes. Evidence shows that elevated levels of estrogen can promote breast cell proliferation, which can lead to breast cancer. Xenoestrogens may increase the risk of breast cancer by binding to and acting through estrogen receptors, thereby imitating natural estrogens. The seriousness of this finding cannot be underlined enough. Breast cancer is the most common form of cancer in women. In Delhi, 28 of every 100,000 women suffer from breast cancer. According to the Delhi Cancer Registry maintained by the Indian Council of Medical Research, in the past decade the incidence rate in the city has increased by about 10%. It is estimated that 1 in 30 women in Delhi will develop breast cancer at some point in their lives. Recent studies also link xenoestrogens to ovarian cancer. Because the raw material for estrogen production is cholesterol, the ovary, like the breast, is a repository of fat-soluble contaminants. Studies in the US, in 1989, showed that estrogen increases the rate of growth of ovarian tumour cells by 50%, compared to those not treated with estrogen. In the same year, Italian researchers studying the health and habits of women farmers in northern Italy discovered that women farmers exposed to triazine herbicides, such as atrazine, had a three- to- four-times higher risk of ovarian cancer. Both these lines of research suggest that triazine herbicides may be acting as xenoestrogens in the ovaries, a hypothesis that has been supported by more recent research. Studies on rhesus monkeys have shown that exposure to xenoestrogens increases the risk of endometriosis -- a disease in which endometrial cells (normally found lining the uterus) proliferate outside the uterus, causing irregular bleeding, excruciating pain, chronic fatigue and infertility. What is of concern is that endometriosis, a debilitating disease now affecting an estimated 10% of women in their reproductive years, was observed at very low doses of dioxin (a xenoestrogen synthesised as a by-product of the chlorine industry). In fact, the dose was 7-8 times lower than the ‘no-adverse-effect’ level proposed by the WHO (1,000 pg/kg/day), indicating that this guideline may not be protective of human health. The limit now being proposed is about 0.1 pg/kg of body weight, although many already have levels far above this limit. Another concern is the effect of ‘synergism’, whereby even minute quantities of these chemicals can cause immense harm when acting in combination with other chemicals. This is particularly relevant in India, where the body burden of pesticides is already relatively high. Xenoestrogens are also being implicated in other reproductive disorders like infertility, low sperm count, fibroids, early menopause, osteoporosis and autoimmune diseases. Because they derive from oil, most of these synthetic products are, like steroid hormones, fat-soluble and tend to accumulate in areas of the body where fat content is high -- for example, breasts. Given that these new chemicals share properties with steroid hormones, the question arises as to why their potential to wreak havoc with the reproductive system was not considered earlier. The most obvious reasons are not hard to find: sexism in the medical system, as well as a misplaced patriotism, whereby questioning of chemical pesticides was regarded as almost anti-national. Rachel Carson in the US was one of the first scientists to raise questions about DDT. Her 1962 book Silent Spring was accused by industry chemists of threatening the Free World’s food supply. Another reason for the evidence of endocrine disruption not coming to light earlier is located in the nature of estrogenicity itself. The estrogen receptor is far less specific than it was earlier thought to be. Scientists cannot predict whether a chemical can attach to estrogen receptors purely from the shape of the molecule. Estrogen receptors are like locks that accept many different keys. DDT, for example, has only two hexagonal rings and yet is able to bind directly to the receptor. Second, xenoestrogens have many modes of operation. Not all of them latch onto estrogen receptors. Some simply stimulate the manufacture of more estrogen receptor molecules. More receptors mean an amplified response to the estradiol naturally floating through a woman’s body, which may place her at a higher risk of breast cancer. Still other xenoestrogens act in the liver to accelerate the metabolism of estradiol toward the 16-metabolite and away from the 2 pathway. More 16-beta-estriol means more bio-available estrogen and more damage to DNA. The weed killer atrazine seems to have this effect. Much current knowledge about xenoestrogens’ impact on fertility and reproduction is derived from animal studies. Wildlife biologist Dr Theo Colburn had conducted long-term and intensive studies of animals in the Great Lakes Basin in the US, an area highly contaminated with organochlorines from chemical industries and pulp and paper mills, which use great amounts of chlorine bleach. Her research documents that many animal species living near water -- eagles, mink, fish and various shore birds -- are unable to reproduce successfully due to high body burdens of various xenoestrogens. Colburn, co-author with Diane Dumanoski and John Petertson Myers of Our Stolen Future (1996) is currently working on elucidating what she calls “the human/wildlife connection”. Particularly in focus is declining fertility and the possible link between estrogenic pollutants and falling sperm counts in men. She also suspects xenoestrogens could have contributed to the 400% increase in ectopic (outside the uterus) pregnancies between 1970 and 1987. Not only is present fertility at risk but also the well-being of future generations. Research in industrialised countries has implicated xenoestrogens in higher rates of spontaneous abortion, foetal death and intra-uterine growth retardation. In addition to the amount of exposure, the timing seems to be crucial. Exposure during foetal development or during early infancy can have serious implications for future development. Studies in Mexico, for instance, have shown links between heavy exposure to pesticides and impaired child development. The neuro-behavioural impact on children -– cognition, memory and motor ability -- has far-reaching significance. Closer home, in Kasargod, Kerala, aerial spraying of endosulfan over state-owned cashew plantations has recently been implicated in a high rate of cancers, birth defects, epilepsy and psychiatric disorders. Besides in-utero exposure, infants are vulnerable to ingestion of pesticides through breast milk. A 1993 study in Punjab -- the lap of the Green Revolution -- found that 80% of food samples were contaminated by DDT; all 244 samples of milk and its products, and all 130 samples of breast milk, contained residues of DDT. The citizens of Delhi have one of the world’s highest levels of DDT in their body fat, and each newborn is unwittingly ingesting this poison through mother’s milk. Experts estimate the daily DDT intake of breast-fed infants in Delhi to be 46 times higher than the safe limits prescribed by international watchdog organisations. Although DDT was withdrawn from use in agriculture in 1989, it continues to be used in the public health programme for malaria eradication, since the short-term benefits are prioritised over the long-term risks. More and more evidence is pointing to the undeniable correlation between pesticide use and health risks. However, many of the existing reports suffer from small sample sizes, difficulty in determining actual exposure, and lack of control groups. Cause and effect is thus difficult to prove ‘beyond all doubt’. The burden of scientific proof has posed a monumental barrier in the campaign to protect health and the environment. Actions to ban or prevent the use of hazardous products are usually taken only after significant proof of harm is established, at which point it might be too late. The Precautionary Principle might be a more useful concept than risk assessment, which is usually the tool employed by policymakers. Instead of asking what level of harm is acceptable, the precautionary principle asks: How much contamination can be avoided? What are the alternatives to this product or process, and are they safer? Is this activity even necessary? The principle is to focus on options and solutions rather than risk. This approach also serves as a `speed breaker’ to new technology, ensuring that decisions about new technologies and products are made thoughtfully and in the light of potential consequences. Common citizens and vulnerable populations need to be made aware of the role of vested commercial interests. The link between industry and ill-health is too close to be overlooked. To quote one instance, National Breast Cancer Awareness Month in the US was founded and sponsored by Zeneca Chemicals. The focus is on early detection, and there is no mention of prevention. Ironically, Zeneca earns millions of dollars from the sale of insecticides, including the carcinogenic herbicide acetochlor! It also earns millions each year marketing the world’s ‘best-selling’ drug -– the controversial tamoxifen -- to treat breast cancer, despite an FDA warning that tamoxifen might actually increase the risk of uterine cancer. When Paul Mueller, the Swiss entomologist who discovered the insecticidal properties of DDT, was awarded the Nobel Prize for Medicine in 1948, little did the world know the havoc his discovery would create for human beings. It is only in recent years that calibration of ‘recommended intake’ levels and other regulatory mechanisms have been put in place. Yet, most current regulations are based on the assumption that humans and ecosystems can absorb a certain amount of contamination without being harmed. There is extreme uncertainty about ‘safe’ or ‘acceptable’ levels, and it is now being established that in many cases these levels cannot be identified. DDT is one of the most prevalent chemical disasters ever, and it is incumbent on today’s scientists and policymakers to evolve new principles and a code of ethics to ensure that this disaster is never repeated. (Laxmi Murthy is a freelance journalist specialising in gender and development. She has been active in the women's movement for the past 18 years) InfoChange News & Features, September 2003
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