We have put together a brief overview of the environmental links to human health with particular emphasis on breast cancer to help you with this project. Because it is by no means comprehensive we suggest you seek further information from the references listed in this pack.

"As we wrestle with the question of how much chemical contaminants are contributing to the trends and societal patterns we see - in breast cancer, prostate disease, infertility and learning difficulties - it is important to keep one thing in mind. Scientists keep finding significant, often permanent effects at surprisingly low doses. The danger we face is not simply death and disease. By disrupting hormones and development, these synthetic chemicals may be changing who we become. They may be altering our destinies." (1)

While it has been known for some time that the majority of human cancers are caused by external factors, it is only in more recent times that the impact on human and animal health of industrial, pharmaceutical and agricultural chemicals has become more evident. That women's health can be used as an indicator, of the state of the environment, is a perspective not often taken. But increasingly well documented evidence supports the fact that women (and consequently children) are the first to experience the effects of environmental degradation.

An epidemiological study carried out in 1997 by the University of Birmingham discovered that children living near different kinds of industrial sites might have as much as a 20% higher rate of illness especially cancer. The researchers looked at cancer incidence in Britain between 1953 and 1980 and grouped incidence rates using postcodes: " for most sites the increased risk of illness was about 20%." (2)

Although concern was expressed about the methodology of the research, in highlighting a worrying link between living near an industrial site and susceptibility to ill health, this study raises some issues that need further investigation.

In the early 60s biologist Rachel Carson's book "Silent Spring" shocked readers into the realisation that "Our fate is connected with the animals". Massive loss of birdlife after aerial spraying with DDT (Dichlorodiphenyl trichloroethane - a pesticide) in certain regions of America in the 1950s led Carson to speculate about the effect on humans living in those regions. (3)

"During the early 1980s, scientists found an unusually high incidence of fish exhibiting both male and female reproductive organs (hermaphrodites) downstream of sewage works on the River Lea in Hertfordshire, and similar effects were observed in rivers in Florida, and in the American Great Lakes...(suggesting)...that environmental levels of certain chemicals were high enough to affect the reproductive systems of aquatic species..." (4)

The Royal Society for the Protection of Birds (RSPB) has linked the decline in the numbers of British birds to the increased use of pesticides on cereal crops. (5) It is only reasonable to expect that the effects found in wildlife are likely to be mirrored in humans, and if 'our fate is connected with the animals', we should surely be assessing their experience as if they were canaries in a mine. What we don't know, is to what extent polluted air, food, soil and water are contributing to our ill health and possibly to increasing rates of breast cancer.

"A cancer cell...is made, not born" they are both primitive and invasive with a capacity for "unrelenting growth". Armed with this knowledge we must assume that something sabotages the cell in order to make it turn from its predestined path and invade healthy tissue in order to cause cancer. We each possess forty-six chromosomes which in turn are made up of many thousands of genes. They are constantly growing and dividing. Each time they divide they run the risk of creating mistakes in their genetic blueprint. Cumulative genetic mistakes can lead to cancer". (6)

Breast cancer

"One may speculate about why so little attention has been paid to efforts to prevent a disease that afflicts so many women, but the fact of this deficit remains glaringly clear. Prevention is less glamorous than treatment, and fewer profit financially if it succeeds". (7)

In the last 10 years, breast cancer in women has increased worldwide by 33%. (8) While the reasons for this dramatic increase are still to be uncovered, various studies have linked our environment and the substances we are exposed to as prime suspects: "....there is growing evidence that the nation's present breast cancer epidemic is related to exposure to a wide range of environmental contaminants, including DDT, other carcinogenic pesticides, and oestrogenic stimulants." (9)

There are over 70,000 chemicals in current commercial use today and 1,000 new ones are added each year. (10) A chemical may not of itself instigate cancer but it may work, in combination with many other substances, both natural and synthetic, to contribute towards the risk of developing disease, including breast cancer.

"In 1994, the New York State Department of Health released the results of a case control study of Long Island women that showed a significant association between residence near chemical plants and risk of contracting breast cancer." (11)

When an earlier 1980s study of Long Island showed no link between the incidence rates for breast cancer and the environment, local women, who had noticed that incidence rates were 10% to 20% higher in Long Island than in the rest of New York State, set about drawing their own maps of the area to demonstrate the need for further investigation. (11,12,13)

Until recently, countries like Japan had a relatively low incidence of breast cancer, yet Japanese women migrating to countries with higher incidence rates began to match the rate of their host country within a generation. This may partly have been due to dietary differences such as altered soya and/or fat intakes in their new country. Unfortunately Japan has shown the greatest rate of increase for breast cancer in recent times and some researchers point to the industrialisation of the country as well as the heavy use of agricultural chemicals. (14)

Current, though controversial, indicators for increased breast cancer risk include lifestyle factors such as high socio-economic status, late-age first childbirth, poor diet, lack of exercise, obesity, alcohol consumption and cigarette smoking; and those risk factors over which we have no control such as family history of breast cancer, age at onset of menarche and menopause, and also the environment we inhabit from the foetal to the final stage of our lives.

"However, established risk factors don't appear to completely explain the high incidence of breast cancer, especially high 'clusters' of breast cancer in certain geographic regions...This leads some investigators to question the role of environmental chemicals, including pesticides, in determining breast cancer risk. Of particular interest are chemicals and pesticides that mimic the action of the female hormone oestrogen." (15)

Oestrogen

From before birth and throughout the whole of our lives many of our vital body functions (e.g. growth, reproduction, metabolic rate, intelligence and behaviour) are controlled by hormones acting within the endocrine system - a complex system like a giant labyrinth composed of long corridors. At the end of each corridor is a 'door' (receptor sites) and for each of these doors there is a specific 'key' (hormone) to unlock it, enter, and carry out its specific task. Without either access or key, a hormone is unable to carry out its task.

Oestrogen, the main hormone implicated in breast cancer, controls a variety of different processes in women's bodies e.g. regulation of menstrual cycle and cholesterol levels, maintenance of bone mass. (16) Its production varies over a lifetime, beginning at birth, reaching a peak at puberty and then levelling off. Excessive oestrogen can stimulate the growth of breast and uterine cancers and the more oestrogen we are exposed to in our lifetime, the greater our risk of developing breast cancer.

The three main types of oestrogen present in the human body - oestradiol (the main and most potent oestrogen) oestriol and oestrone - are produced mainly in the ovaries with smaller quantities being secreted from the adrenal glands, from the placenta during pregnancy and from fat cells. Both oestradiol and oestriol are known to promote breast cancer, while oestrone, a much weaker oestrogen, appears to inhibit breast cancer. (17) The fact that larger quantities of oestrone are produced during pregnancy seems to support the theory that the more children we have the greater our protection might be against breast cancer. As oestradiol breaks down in the body it divides into two pathways, 16aHydroxyestrone (16aOHE) associated with a higher breast cancer risk and 2-Hydroxyestrone (2-OHE) which is associated with a lower breast cancer risk. (17)

Studies of sex hormones in rural Chinese women as opposed to British women show increased levels of oestradiol in British women. This may be accounted for by comparatively greater body mass in British women and the fact that Chinese women, on average, had later menarche, earlier first birth and earlier menopause than British women. Levels of oestradiol in the blood of the British women were 36% higher in the 35-44 age group, 90% higher in the 45-54 age group and 171% higher in the 55-64 age group. This particular study did not look at the dietary differences between the two countries. (18)

Oestrogen mimics

"We have strong scientific evidence about toxic chemicals in the environment that mimic female sex hormones and overload a woman's hormonal system, a known cause of breast cancer. We know how pesticides, industrial pollutants, atomic radiation and other factors are linked - part of the social context of breast cancer. Yet, neither government agencies nor societies responsible for dealing with breast cancer acknowledge this context. WHY?" (19)

An oestrogen mimic may interfere with the our hormone regulation in different ways e.g. it may block the pathway so the natural hormone may not reach its receptor site; it may pretend to be the hormone and initiate an abnormal response; it may fit into the receptor site and block the hormone pathway or it may interfere with the metabolism of hormones or their transport in the body. It may also push the body down the pathway of producing too much 16aOHE which is undesirable in terms of breast cancer, whereas a higher ratio of 2-OHE is likely to be more beneficial and possibly protective. (20) A large number of chemicals are oestrogen mimics - at least 52 have been identified as interfering with our endocrine system (10) and many of those are also carcinogenic.

Synthetic compounds which have shown hormone-like activity in laboratory tests include organochlorine pesticides; combustion and waste by-products (furans and dioxins); surfactants used in pesticides, paints and cleaning products, and in paper and textile production (alkyphenol polyethoxylates); synthetic resins used in can linings and dental fillings (Bisphenol-A); plasticisers in food packaging plastics (polychlorinated phenyls & phthalate esters) (21)

With their capacity to increase our hormonal load as they accumulate in body fat over time, many of these compounds (generally referred to as endocrine disrupting chemicals (EDCs); hormone disrupting chemicals (HDCs); xenoestrogens or gender-benders) can influence the way in which hormones work in our bodies: "Endocrine disrupting chemicals have been reported in semen, the ovarian follicle, the womb environment, and in breast milk at especially elevated concentrations, each chemical with its own mix of mechanisms of actions and unique target sites". (22)

Certain chemicals can pass through the placenta from mother to developing foetus. Since the foetus is exquisitely sensitive to even minute quantities of HDCs, it has been suggested that the chemicals we are exposed to in the womb may have an effect years later. (23) For example, a synthetic oestrogen, Diethylstilbestrol (DES) was given to over five million women from 1948-1971 and is regarded today as a "model for the problems that other oestrogen-like substances may cause". (24) Originally prescribed to prevent miscarriage, DES was also used for menopausal symptoms, as a "morning after" contraceptive, for girls who were growing "too tall" and most bizarrely of all, by farmers to fatten chickens, cows and other livestock. Years later, daughters and sons of women who took the drug developed various cancers and genital abnormalities. (25)

We know oestrogen mimics interfere with hormones, male and female, human and animal. What is not known is exactly how and to what extent they do this. However, more and more people support the view that: There is sufficient evidence to indicate that the problem (endocrine disrupting chemicals) is grave and therefore, based on the precautionary principle, action to reduce discharges should be taken now. (26)

Alkyphenols (APs)

APs are the breakdown products of Alkyl Phenol ethoxylates (APEs) which are used in paints, industrial detergents, pesticides, insulating foams, cosmetics, for industrial wool scouring, (27) and as wetting agents in nappies and sanitary towels. (28) They are persistent in the environment, have been detected in rivers, lakes and streams, are bio-accumulative and can stimulate the growth of breast cancer cells.

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