When Margaret Sanger wrote, “Woman must have the fundamental freedom of choosing whether or not she will be a mother and how many children she will have,” she wasn’t thinking about the increased rate of miscarriage among farm worker women exposed to pesticides. Nor was Maggie challenging the chemical industry for impeding the freedom to choose because of the science linking chemicals to the incidence of fertility-harming endometriosis among women and girls.

But the world was different for Margaret Sanger. When she was born in 1879, most industrial chemicals didn’t exist. It was only after World War II that the US petrochemical industry discovered “peaceful” applications of synthetic, or man-made, chemicals that would maintain their wartime production levels. New materials, pesticides, pharmaceuticals and plastics dramatically changed and improved the way we lived. By the time the evidence of human and ecosystem health problems led the United States to regulate industrial chemicals through the Toxic Substances Control Act (TSCA) of 1976, there were already 80,000 chemicals on the market. Rather than truly protect public health by issuing a comprehensive review process for these chemicals, TSCA deemed all 80,000 to be safe without pre-market testing, unless the EPA could prove otherwise.

The presumed innocent until proven guilty rule lets companies produce chemicals and put them into the products we use every day without providing evidence for their safety. While most people assume that chemicals are tested like pharmaceuticals – that manufacturers have to prove they are safe and effective before they can be sold – the opposite is true. In the thirty-one years since TSCA put the burden of proof on the EPA, the agency has only managed to review the safety data of less than two percent of the 80,000 chemicals that were on the market in 1976 and has only regulated five of these chemicals.

While TSCA’s ability to protect the American people from chemical exposure has weakened, evidence that chemicals can harm human health has mounted. Especially compelling is emerging research showing that chemical exposures that occur prior to conception, during pregnancy and early in life can have ramifications on adult health. Pre-term birth or low birth-weight, birth defects, diabetes and cardiovascular disease in adulthood have all now been linked to early exposure to chemicals and other environmental contaminants.

In addition to impacting healthy pregnancy outcomes, chemicals may also be playing a role in whether a woman can become pregnant in the first place, if she chooses to do so. At least twelve percent of the reproductive-age population reports difficulty conceiving and/or maintaining pregnancy. This appears to be a rising trend, most markedly in women under twenty-five years old.

The increased rate of endometriosis is one reason that reports of infertility are going up. Endometriosis is a disease that causes tissue that ordinarily lines the inside of the uterus (called the endometrium) to grow outside of the uterus and in other parts of the body, for example, the ovary, abdomen and pelvis. About ten to twenty of women of reproductive age in the U.S. now suffer from endometriosis, and rates have been rising in the past 50 years, particularly among younger women. The link between chemical exposures and endometriosis was first recognized in 1993, when rhesus monkeys that had eaten food contaminated with dioxin began to develop endometriosis.

The right of a woman to decide when and if to become a mother may also depend on her partner’s ability to father a child. So the freedom to choose includes access to healthy sperm produced with plenty of testosterone. But sperm counts and testosterone levels have been going down in many parts of the world, and testicular cancer is going up. In some industrialized areas, sperm counts have gone down 50 percent over the last 50 years. More baby boys today are born with two birth defects of the reproductive system – hypospadias (deformity of the penis) and cryptorchidism (undescended testicles) – developmental problems that have also been linked to low sperm counts and testicular cancer later in life. New evidence suggests that all of these conditions may be caused by the same prenatal exposures.

Chemicals like phthalates, bisphenol A, and perfluorinated compounds are found in many consumer products such as baby bottles, food can linings, Nalgene water bottles, children’s toys, plastic food containers, cosmetics, dental fillings, furniture and wrinkle-free clothing. Data from the US Center for Disease Control shows that almost every person now has detectable levels of contaminants in their bodies – some even at levels near or above those shown in scientific studies to cause adverse effects.

Well-designed animal studies are showing how prenatal exposures to these chemicals can add up to harm, mirroring similar problems in people:

Bisphenol A found in polycarbonate plastic and can linings can cause permanent changes and increased risks of reproductive health problems later in life, such as infertility, miscarriage, breast cancer, and prostate cancer.

Prenatal exposures to phthalates found in personal care products and commodities made of vinyl have been linked to reproductive health problems in males such as reduced testosterone, reduced sperm count and infertility.

Prenatal exposures to PFCs (perfluorinated chemicals), common in stain-proof and stick-free products and found in almost everyone tested in the US, can cause irreversible damage in animal offspring and has been linked to decreased birthweight in humans.

Consumer campaigns like the Campaign for Safe Cosmetics are convincing manufacturers to move away from the use of some of these chemicals, while green chemistry scientists are increasingly discovering new ways to manufacture and produce safe alternatives to these chemicals. But we need comprehensive reform of the federal chemicals policy, so that chemicals are proven safe before they are put into the products we use every day, and manufacturers are given incentives to put more effort into researching and incorporating non-toxic chemicals in their design. And before we can create that sweeping reform we will need to build a movement for the twenty-first century right to choose that includes the right to be able to get pregnant and to have a healthy child.