(Beyond Pesticides, July 16, 2007) In its report released on Father’s Day 2007, “Men, Boys and Environmental Threats,” the Canadian Partnership for Children’s Health and Environment urges greater awareness among parents about environmental risks to boys. “All children are at risk from exposure to environmental hazards, but boys appear to be at greater risk,” said Dr. Lynn Marshall, MD, with the Ontario College of Family Physicians.
The report summarizes the evidence about environmental risks to boys, specifically examining cancer, asthma, learning and behavioral disorders, birth defects and testicular dysgenesis syndrome. Below is a summary of the report’s findings.
Cancer: Although cancer is rare among all children, more boys are diagnosed with cancer than girls. Among young adults (age 20—44) several cancers are on the rise, including testicular cancer. Concern arises over parents’ exposures before conception or during pregnancy. Childhood cancers are associated with exposures to pesticides, solvents, petroleum products, motor vehicle exhaust, benzene and other pollutants. Much remains unknown. Since cancer involves problems with cell division, it is logical that exposures during times of rapid cell division (especially in the womb) likely pose the greatest risk.
Asthma: In the past 20 years there has been a dramatic rise in asthma in children. Less well known is that more boys have asthma than girls and more are hospitalized for it. Boys are born with smaller airways, relative to their lung size, than girls. They also tend to have more allergies, which can contribute to developing asthma. Asthma is a complex disease. Evidence shows that it results from interactions between genetics and environmental triggers. Such triggers include indoor and outdoor air pollution and also include some pesticides and chemicals in household cleaning products.
Learning and Developmental Disorders and Disabilities: Large numbers of children have learning and behavioral disorders or disabilities. The apparent increase in autism in recent years is of concern. For unknown reasons, boys are at greater risk for autism as well. More boys than girls have autism, Attention Deficit Hyperactivity Disorder (ADHD), learning disabilities, Tourette’s syndrome, cerebral palsy, and dyslexia. For autism and ADHD, boys outnumber the girls by up to four to one. We know that children’s brains can be damaged by lead, mercury, arsenic, radiation, dioxins, PCBs, solvents and some pesticides.
Boys’ brains may be more vulnerable for several reasons. There are genetic differences, slower rates of maturity and greater vulnerability to physical injury. Brain development and the pattern of hormone production in the womb are different for boys than girls. Recent studies of adults reveal gender differences in brain structure, function and chemistry. These differences may make boys more vulnerable to chemical exposures. As well, there are a larger number of cell divisions in males during fetal development, which increases the chances of genetic errors occurring.
Birth Defects: Birth defects occur in about two to three per cent of births in Canada – boys are affected more often than girls. About half of birth defects affecting boys include cryptorchidism (undescended testicles) and hypospadias (a defect of the male urinary tract). Stillbirths and miscarriages, which often can be due to birth defects, also seem to be more common in male babies. Many factors can contribute to birth defects including genetics, infection during pregnancy, and environmental factors. While much remains unknown, interaction of multiple factors is likely. We know that certain chemicals can impact development, including lead, mercury, radiation, and PCBs contaminated by dioxins and furans. Scientists suspect there are many more contaminants that come into play, including some pesticides, organic solvents, and some air pollutants.
Development of the male reproductive system has more steps and is more complex than for the female system. As a result there are more chances for error. Rapid cell growth creates a higher risk of incorporating errors during development than cells growing more slowly. Where defects originate in an X chromosome, females have a chance to “neutralize” this defect with another X chromosome, while males have only one X
Testicular Dysgenesis Syndrome: Scientists describe a group of impacts on the male reproductive system under the term Testicular Dysgenesis Syndrome (TDS). TDS includes the birth defects cryptorchidism and hypospadias, as well as poor semen quality (i.e. reduced sperm count, abnormal sperm), decreased fertility and perhaps also testicular cancer. Scientists suspect chemical exposures during pregnancy, specifically during the time when the male reproductive system is developing, may be causing these related impacts. Hormones (the endocrine system) play an important role in the development of the fetus. Scientists suspect that TDS results from chemicals that can disrupt these hormones. Called “endocrine disruptors,” scientists have shown these effects for a few chemicals including PCBs, dioxins and some pesticides.
The report encourages parents, especially fathers, to take an active role in protecting their children from environmental risk factors. A checklist of preventive measures is included in the report.
For more information on children and pesticides, visit Beyond Pesticides’ Children and Schools webpage.