The Cases of Asthma, Learning Disabilities and Breast Cancer

The number of children and the total number of people with asthma has more than doubled since 1980.

The percentage of women developing breast cancer and men being diagnosed with prostate cancer is going up every year.

Endometriosis now affects 10 to 15% of all women of child bearing age. It can cause scarring and blockages that prevent a woman from becoming pregnant.

What’s going on? Why are so many people getting sick? And what can we do so that, in the future, there is less suffering from asthma, infertility, learning disabilities, birth defects, childhood leukemia, and cancer?

While we don’t have complete answers to these questions, science is giving us more and more evidence that our health problems are tied to problems in the environment.

The Example of Asthma:

Why do twice as many people have asthma now as compared to 25 years ago? And why are more people with asthma having more serious attacks?

It can’t be explained by an increase in bad genes. While we know that asthma is genetically linked, more and more people with no family history of asthma are getting the disease.

It’s not that our homes have twice as much dust. In fact, there are no differences in asthma rates in dry, cool regions with low levels of house-dust mites and fungus compared to warm, humid areas where levels are high. And studies have not shown that children with less exposure to household allergens—the substances that trigger an allergic response are any less likely to develop asthma.

It’s not just cigarettes. Exposure to second-hand smoke before and after birth is linked to asthma risk. But if this were a large factor, asthma rates should be going down because fewer people are smoking.

So if it’s not primarily genetics, more allergens in our homes or cigarettes, what is causing the increase in asthma?

There is no single answer. But studies show part of the answer is exposure to chemicals in the womb or shortly after birth that change the immune system so it becomes much more sensitive to allergens. For example, a recent study found that infants exposed to herbicides and pesticides before they are one years old are much more likely to develop early persistent asthma.

Part of the increase in asthma comes from too few breast-fed babies. Breast-fed infants are less likely to develop asthma and allergies compared to those fed infant formula. Breast-feeding improves a baby’s immune system, making the child more able to resist  allergens.

Doctors working with CHE have collected studies showing the connections between 200 human health problems and chemical contamination. In the CHE matrix, asthma is strongly linked to 17 groups of chemicals.

Another factor is diesel engine exhaust. Ozone and fine particle pllution from diesel exhaust appears to change some immune cells  to a type that is linked to the  development of asthma. Kids growing up along streets with heavy truck traffic are more likely to have asthma-related respiratory symptoms.

And, part of the reason for the increase in asthma comes from changes in indoor air quality from chemicals that are now added to the products we use to build, decorate and maintain our homes, schools and workplaces. Very few of these chemicals have been tested for effects on the developing immune system, even though it is clear that exposure in the womb can alter immune function later in life. These chemicals  can also trigger asthma attacks in people who already have the disease.

So while we don’t understand completely all the causes for the increase in asthma, we do know what can be done to prevent the numbers from continuing to climb:

• Keep chemicals that can harm the immune system away from people, especially infants and women who are or may be pregnant.
• Promote breast-feeding.
• Decrease the use of diesel-fueled vehicles.
• Build buildings and products without chemicals that harm indoor air quality.

The Example of Learning Disabilities:

Learning and developmental disabilities affect 1 in 6 children under 18 children in the United States. About 2 out of every 1,000 children have autism. Autism and learning disabilities appear to be increasing, although it is not known how much of the increase might be due to better reporting or changes in diagnosis.

We know that genetics, drugs, poor nutrition, German Measles, and other infectious diseases, brain trauma or tumors and a lack of oxygen before or shortly after birth can all impact brain development. And we also know that the  developing brain is extraordinarily sensitive to toxic chemicals — exposure levels that have no lasting effect on an adult’s brain can have dramatic effects on the developing brain before  birth or during childhood.

• Lead exposures during infancy and childhood can cause attention problems, hyperactivity, impulsive behavior, reduced IQ, poor school performance, aggression, and delinquent behavior. The more we study lead, the more evidence we have showing that levels previously thought “safe” can in fact cause harm to the developing brain.
• Mercury easily crosses the placenta when in the mother’s system and disrupts many crucial steps in brain development. Even exposures at relatively low levels to a pregnant woman can impair the IQ, language development, visual-spatial skills, memory, and attention capabilities of her child. As with lead, the “safe” level of mercury keeps dropping as mercury is studied further.
• Manganese is essential to health at low levels in the diet,  but elevated levels of manganese in hair are associated with Attention  Deficit hyperactivity disorder (ADHD), and laboratory experiments  in animals link manganese with hyperactivity. Excessive exposure to Manganese can also cause a disorder that looks like Parkinson's Disease.
• PCBs (polychlorinated biphenyls), industrial chemicals now banned but which persist in the environment and people, especially in fatty tissue, can impair reflexes and IQ, delay mental and motor development, and cause hyperactivity.
• Tobacco smoke and nicotine are among the best studied agents for their effects on the developing brain. Children born to women who smoke during pregnancy are at risk for IQ deficits, learning disorders, and attention deficits. Children born to women who are passively exposed to cigarette smoke are also at risk for impaired speech and language skills, and reduced intelligence. Children exposed to tobacco smoke after birth are at risk for various behavioral problems.
• Alcohol crosses the placenta and disrupts many steps in brain development. Depending on the timing and amount of exposure to a pregnant woman, the exposed fetus may develop into a child with hyperactivity, learning problems, lowered IQ, or in more serious cases, mental retardation.
• Bisphenol-A, a component of polycarbonate and some other plastics changes the operations of the genes that are important for long-term memory formation and for early brain development. Fetal mice exposed to extremely low doses of bisphenol A show changes in their adult behavior.
• Perchlorate, a rocket fuel that now contaminates drinking  water and some vegetables in many communities in the US, interferes with thyroid hormone control of brain development in  mice.
• Solvents like toluene cause learning, speech, and motor skill problems in children. These effects were discovered in studies of children born to mothers who sniffed glue during pregnancy.

The chemicals noted here have been studied intensively for their impacts on the brain. However, the vast majority of chemicals to which people are commonly exposed have never been examined for their impacts on the brain of the developing fetus. Even though evidence coming from laboratory experiments points to possible impacts on people from these less studied chemicals, there are many gaps in the science between what we understand today and reaching scientific certainty. At this point, however, we already can – and should -- make targeted recommendations about ways that exposure reduction might reduce risks:

• Redesign products so they do not contain lead, mercury, bisphenol A and other chemicals known to harm the brain.
• Educate women who are or may be pregnant, or planning a pregnancy, about the risks of smoking, alcohol, solvents and eating fish that are contaminated with mercury or PCBs.
• Clean up contamination from lead, perchlorate and other brain-harming chemicals.
• Work to change government policies so chemicals must be tested for their possible health impacts before they are put into use.

The Example of Breast Cancer:

Breast cancer is the most common cancer in women in the world, in both industrialized and developing countries. In the United  States, 1 in 7 women will get breast cancer in their lifetime. Fifty years ago, the number was 1 in 22.

Less than one third of breast cancers are linked to inherited genes. Ionizing radiation from x-rays and other nuclear sources, alcohol, and the synthetic estrogens in hormone replacement drugs are other known causes of breast cancer.

Many environmental exposures are being studied as possible breast carcinogens. Electromagnetic fields and light at night have shown associations with breast cancer in a few studies. The chemicals found in soot and smoke are known carcinogens that have been linked to mammary tumors in animals. Several studies have found associations between exposure to soot and smoke and breast cancer in humans.

We know that more estrogen increases breast cancer risk. That’s why breast cancer incidence is linked to whether or not a woman has born a child, how old she was when she had children, whether or not she breast-fed, when her menstrual periods started, when she entered into menopause and if she has been overweight.

The role of estrogen in breast cancer risk has raised the possibility that environmental contaminants that act as estrogens or anti-estrogens might also be involved. Early studies indicated a positive association between several compounds containing chlorine and breast cancer. Then came studies that cast doubt on some of these findings. Most recently, studies have shown links between the compounds diethylstilbestrol and dioxin and breast cancer.

The chemical exposure that is linked to the disease can come many years before the diagnosis of the illness. Research in the laboratory with animals and studies of women show that the cell changes that sow the seeds for breast cancer can be detected.

In the real world chemical exposure comes in mixtures, but if chemicals are tested at all, they're usually tested one  at a time.

In our bodies, chemicals interact with our genes, our nutritional status, whether or not we smoke and other factors. So we can't say that toxic chemicals that act like estrogens are the cause for the increase in breast cancer. But we can't say that  they are not the cause, either.

What do we do to reduce the incidence of breast cancer? More sophisticated studies will help us figure out exactly what is going on. But in the meantime, common sense efforts that minimize our exposure to chemicals that may cause breast cancer seem like a pretty good idea.

These efforts could include:

• Healthy purchasing, with both governments and corporations preferring products that are made with no or few toxic chemicals, starting with those chemicals that we know act like estrogen.
• Monitoring the chemical body burden in humans, using blood, urine, and breast milk to identify the synthetic chemicals in people and to establish links to geographic areas and health outcomes.
• The phase out of toxic chemicals that persist and accumulate in our bodies and in the larger environment.

What can we do about the increase in disease and the links between these diseases and the environment? Plenty. As an individual you should not smoke, you should eat a healthy diet, limit alcohol, especially if you are a woman who may be pregnant, be careful about outside exercise on days with high ozone levels, avoid using pesticides, eat the fish and seafood that have lower levels of mercury and PCBs and buy products that don’t contain PVC, phthalates, bisphenol A or other dangerous chemicals.

But there is much more we can do as citizens of a democracy. Below are some innovative policies aimed at improving human health by decreasing environmental problems.

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