To answer that question, we have to start with another: what actually makes a man a man? We all learn in science class that a person's biological sex starts with genes. The mother's egg carries an X chromosome. If the father's sperm carries a Y chromosome, the resulting embryo will be a boy. If the sperm carries an X, it will be a girl. Together, mother and father sex chromosomes form an embryo, either XY (boy) or XX (girl).
But gender is more complicated than genes.
After sperm and egg become acquainted, the embryo's reproductive tissues
begin to develop. For about five weeks this process is identical in
both males and females. Then, if the embryo is male, certain cells begin
to grow and release testosterone, initiating development of the entire
male reproductive system - including the prostate gland, penis, urethra
and scrotum. At this time the brain is wired to set the stage for further
maturation during puberty, and in the last two months of fetal development,
testosterone signals the testes to descend into the scrotum.
Testosterone-induced development continues in boys throughout the first few years of life. Then things get quiet for a while until puberty, when the hormone raging begins again. It's hard to imagine how just a handful of hormones -- testosterone, estrogen, thyroid and a few other natural chemicals produced inside the body -- orchestrate, through a complex and delicate balance of hormone signaling, the growth and development of all tissues and organs, including the reproductive system. It is even harder to grasp how significant changes in development and health can come from absolutely infinitesimal amounts of these natural chemicals.
So when tiny amounts of hormonally active synthetic chemicals get into our bodies from the food we eat, the air we breathe, the water we drink and the products we use every day, they too can cause major health impacts, even at very low doses. They can disrupt the sensitive hormone balance by blocking natural messages or sending their own misleading signals that fool the body into doing the wrong thing at the wrong time.
Thousands of peer-reviewed, published studies (mostly animal studies) suggest that certain human reproductive health problems are tied to synthetic or industrial chemical exposures. In males, these problems include two common birth defects: cryptochordism (undescended testicles) and hypospadias (a deformity of the penis), both of which have also been linked to low sperm counts and testicular cancer later in life. All four of these conditions, collectively called testicular dysgenesis syndrome (TDS), can arise from the same origin - disrupted hormone signaling in the womb during critical stages of male reproductive system development.
Animal studies have demonstrated time
and time again that prenatal exposures to chemicals - including vinclozolin
(a widely used fungicide), phthalates (found in PVC plastic and personal
care products), bisphenol A (found in polycarbonate bottles and the
linings of canned foods and beverages), and the banned but still present
industrial chemicals DDT and PCBs - can cause TDS.
Statistical analysis shows that TDS conditions are on the rise in humans, particularly the incidence of low sperm counts in most highly developed countries. In several industrial regions, sperm counts have dropped fifty percent over the last 50 years, and several new studies suggest that testosterone levels may have declined 1% per year for the past 40-50 years. In the United States alone, testicular cancer has dramatically increased since the 1970s, with a reported 60% increase among whites and Asians, and 40% increase in blacks.
So what can men and their families do, to protect their ability to become fathers, and increase their chances of living a long and healthy life? Green purchasing helps. Buying products that are free of phthalates, pesticides, bisphenol A and other chemicals gives us a way to protect ourselves and contributes to the broader effort to shift markets and move the economy in a healthy direction. Many resources exist that can help guide families, communities, and institutions to greener products.
Green policies help even more. A few cities, several states and the federal government are all currently considering bills that would restrict the use of phthalates, bisphenol A and other environmental contaminants; put research dollars into green solutions; and require companies to prove that chemicals are safe before they are put into products and released on the market. Those bills and the elected officials that support them deserve our support. Chemical and product manufacturers continue to argue that animal studies should not be used to determine human health policies, but the U.S. Food and Drug Administration (FDA), tasked with protecting public health by regulating food and drugs, routinely relies on animal studies to decide which chemicals are too dangerous to be used as pharmaceuticals. Why shouldn't they do the same for the wide variety of other chemicals that impact our health?
Most importantly, we need to give our fathers, our sons and ourselves a greener future. That can happen once we come to collectively understand how our families' health is connected to the health of everything and everyone else. Anything we can do to reduce harm and prevent unnecessary chemical exposures will protect the health of all men and future generations to come. What better gift could a father ask for?
Learn More!
A new report, "Shaping
Our Legacy: Reproductive Health and the Environment," will be
available in the coming weeks at here. The report comprehensively outlines the science
behind environmental influences to male reproductive health, and points
the reader to many available resources for what you can do.
Check out the Collaborative on Health and the Environment website, and the Commonweal website.
Related Posts
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.
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