Tinkering with the Machinery of Life

Time to give climate change a short break and focus a bit on other ways that our civilization is imprudently tinkering with the machinery of life.

Last week, scientists spoke at the Northwest Children's Environmental Health Forum to share the latest research on the health consequences of chemical exposures.

New information paints a picture that is both more complex and more troubling than we had understood before. Toxic exposures - heavy metals, synthetic chemicals, and combustion byproducts, for example - don't affect the body in isolation. They work in combination with genetic, diet, and social factors at the cellular level, and those combinations might push the body down any one of many paths that could lead to disease.

Environmental exposures are "entangled in a complex causal web," said Dr. Ted Schettler, science director of the Science and Environmental Health Network.

For example, researchers have found that asthmatic children living below the poverty line tend to be more susceptible to asthma attacks during ozone smog episodes than children living in households above the poverty line. What's the explanation? Poor diet? Lack of health care?

Schettler said that stress appears to be a factor. Poverty raises household stress. Take two kids who have asthma and live in a smoggy city. The kid under stress will be more susceptible to an asthma attack than the kid who's not stressed.

Ozone smog is a public health threat that comes around every summer in many of the nation's cities. Lead, however, is a public health success story. Thanks to the removal of lead from gasoline, lead exposure has fallen dramatically.

That doesn't mean, however, that we can stop paying attention to the dangers of lead exposure. Recent research suggests that low levels of lead exposure are associated with incidence of attention deficit-hyperactivity disorder (ADHD) in kids. Dr. Bruce Lanphear, who studies children's diseases and disabilities at British Columbia's Simon Fraser University, co-authored a 2006 report finding an association between low blood levels - less than 5 micrograms per deciliter - and ADHD.

Lanphear said the Centers for Disease Control and Prevention's "action levels" for blood lead levels are too low. In view of the risks,  he said the CDC's action level for blood lead should be reduced from 10 micrograms per deciliter to below 1.

Perhaps the most far-reaching research was the "ghost in the genes" presentation of Dr. Michael Skinner, who studies molecular biology at Washington State University. His work has found provocative evidence that exposure to endocrine disruptors leaves a marker in gene activity that is passed on to future generations, leading to onset of disease in descendants.

In an interview with ScienceWatch.com, Skinner said: "In essence, what your grandmother was exposed to when she was pregnant may cause disease in you and your grandchildren."

The sins of the father - and of the mother - indeed.