A Discussion on Endocrine Disruptors from a Pediatric Endocrinologist

For our focus on doctors, I took the time to interview my father, Dr. Dennis Styne, as he is much of my inspiration for Sprout's mission. He is a professor of pediatric endocrinology and the past chair of the department of pediatrics at the University of California at Davis. He has served on the national committee for the American Academy of Pediatrics and the Pediatric Endocrine Society and authored over 150 publication and chapters. 

What do you do?

I am a pediatric endocrinologist.  That means I have had special training to take care of disorders of the endocrine glands in childhood including such conditions as diabetes, growth disorders, thyroid disease, disorders of puberty and other problems involving hormones.

Can the environment affect the endocrine system?

Yes, endocrine disruptors are chemicals in the environment that have effects similar to hormones and can produce developmental and reproductive changes in those exposed to the disruptors. Thus in my clinical work and my research I study the effects of endocrine disruptors.  Examples of endocrine disruptors include DDT which can still exert impacts decades after it was banned from use.  For example DDT is associated with decreased sperm count and miscarriages and even premature cessation of breast-feeding.  Industrial exposures of dioxin in other countries have delayed puberty in boys and can exert other effects. More recently attention was focused on plastics including those containing bisphenol A (BPA). BPA has recently been banned nationally in baby bottles because of concern that it exerts effects on the developing prostate gland, breast, neurologic system and may even foster the development of obesity. Further, certain phases of human development such as pregnancy and fetal life may allow concentration of the substances so that there are higher exposures.  Endocrine disruptors can be found in everyday life in such locations as the lining of carbonated soda cans, water bottles, and even the receipts that we get out of ATMs or gas pumps.

How do we know that these chemicals are exerting effects?

In places where industrial accidents occur and these chemicals are released in large amounts, we have convincing proof that they affect the development of children.  When these disruptors are experienced in lower amounts in our everyday life the evidence is not as strong, but we all worry that that when exposure occurs during critical periods of development when children and fetuses are uniquely susceptible to these chemicals, the effects might be even more significant.  Presently sperm counts in areas of Scandinavia, as well as the United States, are decreasing and many are concerned that this is due to endocrine disruptors.  In Denmark boys are more frequently now found to have undescended testes (cryptorchidism) or abnormal placement of the opening where the urine exits the penis (hypospadias) and in later life a tendency towards the development of testicular cancer (called the “testicular dysgenesis syndrome”).  It is postulated that these effects are due to exposure to endocrine disruptors.

What are the reasons that there are so many endocrine disruptors in our environment?

It seems that the United States requires proof that an environmental chemical causes damage before it can be investigated and eliminated.  In Norway, as an example, laws require that chemicals are proven to be safe before they can enter the environment.  We can do well to emulate these approaches.  Presently the Endocrine Society and numerous other health organizations have asked for more study of the effects of endocrine disruptors and enhanced regulation of the substances. Continual pressure on Congress to develop better regulation could be effective in demanding change.

What can a parent do to avoid these exposures?

There are certain things you can avoid, such as plastics that contain BPA. Also, while there is no proven increase in nutritional value from organic fruits and vegetables there is a decrease in the exposure to pesticides and other agricultural chemicals in organic products. We have also recently begun to study anti-bacterial soaps and found that anti-bacterial chemicals appears to exert biological effects as they are absorbed through the skin. We are not yet certain what the extent of the effects are and further studies are necessary.

As an endocrinologist you focus on obesity. Is there a link?

We currently have an epidemic of childhood obesity. In large part this is due to poor habits in many cases, such as excessive screen time and lack of activity, but some investigators believe that there might be an environmental factor as well. Many of the endocrine disruptors talked about above are linked to obesity in animals and we are currently studying the possibility that this is happening in children as well.

I have heard that girls are going through puberty earlier than in the past. Is this related?

There is no question that girls are starting puberty earlier than 20/30 years ago. The cause in many cases appears to be the obesity epidemic because excess weight advances puberty. However, the endocrine disruptors and their estrogenic effects offer another potential explanation that we are currently studying.


-Dennis Styne, MD, Professor, Chief of Pediatric Endocrinology, Director of the Newborn Screening Program and Childhood Obesity Clinic, UC Davis Children’s Hospital
Dennis M. Styne is an expert on pediatric endocrine disorders, growth and disorders of puberty, diabetes mellitus in childhood, thyroid disease, and childhood obesity. He played an integral part in establishing a new childhood and adolescent weight management program at UC Davis Medical Center. Styne has been featured in The Best Doctors in America. He is an active leader in the Obesity Affiliation Group, working to foster development of a state-of-the-art, nationally prominent pediatric obesity research and treatment center. He also has a research interest in puberty and fetal and childhood growth.