By Emily Pennington

April 24 through May 1 was National Infertility Awareness Week and according to the National Infertility Association 7.3 million men and women are infertile, which breaks down to one in eight couples. University of Texas Associate Professor in the College of Pharmacy John Richburg knows this all too well. He is at his desk at 7 a.m. every day before most of his colleagues, working sometimes until 7 p.m. to answer the questions about human infertility.

John Richburg

Richburg is a toxicologist whose specialty is finding out how exposure to environmental agents affects male fertility, specifically during puberty. In the summer of 2009, he was awarded a $1.5 million grant from the National Institutes of Health to research how or if phthalates, the chemical compounds found in plastic that allow them to be flexible, induce the death of germ cells, the cells that ultimately develop into sperm in the male testes.

Richburg said phthalates are not covalently bonded into plastic, which means they can leach onto the food or product that comes into contact with phthalate-containing plastics, thus ending up in human bodies. Because of the ubiquitous contamination by phthalates in the environment, he said all humans have certain levels of phthalates in their bodies.

Richburg suggests exposure to phthalates during early childhood or fetal periods of life is more likely to result in infertility, an effect that is often not evident until adulthood, than exposure as an adult.

“If your doctor took a blood sample from you, she would with 100 percent certainty be able to measure levels of various environmental endocrine disruptors using the appropriate lab tests. Women who are pregnant are exposing their developing fetuses to these compounds,” said Andrea Gore, professor of pharmacology and toxicology who studies how disturbance of the neuroendocrine system by environmental factors result in aberrant reproductive functions.

Gore said an organism undergoes its most rapid changes during fetal development, and at that time both male and female reproductive systems are vulnerable.  During this period certain organs and tissues, including reproductive systems and the brain, are formed and develop their potential to function later in life. In the case of reproductive systems, the organization of the gonad in the fetus enables it to have the capacity to produce the proper gametes — sperm or ova — and hormones including testosterone and estrogen in adulthood. If something perturbs this organizational process during the fetal stage, the organism’s ability to perform these functions may be permanently compromised.

Richard L. Corsi is the ECH Bantel Professor of Professional Practice in the Department of Civil, Architectural and Environmental Engineering at UT, where he researches the sources, physics, chemistry, human exposure and control of indoor air pollution.

Corsi said there are several ways phthalates get into the human body: ingesting them after they have leached from plastic bottles, absorbing them through contact with our skin, absorbing phthalates that exist in air as gases by our skin oils that then transfer them through the skin, and inhaling them.

Richburg, who earned his bachelor’s degree in toxicology from Northeastern University in Boston, his doctoral degree in toxicology from Rutgers and a postdoctoral fellowship at Brown University, admitted he was never interested in this area of study when he was in school. As a graduate student he was very interested in cell signaling and what happens when the line of communication between cells is disrupted, which led him to neuroscience. However, another neuroscientist and friend Kim Boekelheide, Richburg’s mentor at Brown, was looking for a postdoctoral student and introduced him to the many similarities between cells of the nervous system and of the testes.

Although researchers have known about the adverse effects of phthalates on male reproduction since the ‘50s, Richburg said that research specifically evaluating the negative influence of phthalate exposure during early sensitive periods of male reproductive development was not widely studied until the late ‘90s. In fact, the lab he worked in prior to coming to UT in ’97 was the first to describe the cell signaling mechanism by which the testicular germ cells are triggered to undergo death after phthalate exposure.

Currently running his own lab at UT, Richburg considers himself a director for the most part. Three graduate students and a postdoctoral fellow currently perform the research in his laboratory. He said the students conduct most of the experiments and form independent ideas as their knowledge and experience grows.

“Research never ends,” Richburg said. “Every time I ask one question we do a little bit of research and we find ten new questions that come up. I guess the goal is to really understand where do we need to be protected from this chemical.”

The trouble with this research is that plastic is a very useful substance — it improves people’s quality of life and is cheap to make. So people must decide if that is worth the damage it does to their bodies, Richburg said.

“The goal is not to outlaw every chemical that comes along, because outlawing one harmful chemical just seems to cause three more to spring up,” he said.

It is only when people understand how a toxic agent works that they can make a rational decision about exposure levels and banning them from products. Some phthalates are not harmful, and the most harmful phthalates have already been outlawed from children’s chew toys and food canisters.

“My work is important and the reason why I enjoy it and the reason why students come to my lab is because not only do we study cell biology but it has human health implications and impacts,” Richburg said.