Studies are showing dramatic drops in sperm counts and rising rates of male reproductive health problems for men throughout industrialized countries. Are environmental contaminants partially to blame?
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.
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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?
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.
- Charlotte Brody and Julia Varshavsky, A 21st Century Right to Choose