All Things in Moderation: Drinking While Pregnant Edition
Does the dose make the poison? In toxic tort litigation plaintiffs have long argued that at the unmeasured and unobserved low dose end of the dose-response curve risk doesn't reach zero until the dose reaches zero. To support their claim they point to regulators' linear no-threshold risk models, they try to throw the burden of proof on defendants and they conclude by saying that since defendants can't prove there's an absolutely safe level for exposure, all levels must therefore be unsafe.
This "no safe level" argument isn't confined to cancer cases and plaintiff lawyers aren't the only ones who make it. Advocacy groups for a variety of human ailments stake out similarly extreme positions. For example, March of Dimes claims that some 40,000 American children are born annually with fetal alcohol syndrome disorders (FASDs). In addition to claiming "no level of alcohol use during pregnancy has been proven safe" they cherry pick data from weak studies to assert that mothers who consume as little as one alcoholic drink per week have children with (a) small heads ("a possible indicator of brain size"); (b) a 300% increase in risk of growing up to be delinquents; (c) a variety of emotional and learning disorders; and, (d) an increased risk of becoming alcoholics and drug addicts. Finally, March of Dimes flatly states "[t]here is no cure for FASDs."
The good news is that there never has been much evidence to support these horror stories and the better news is that there's a brand new study showing that not only are the children of light drinkers at no increased risk of cognitive defects (at least through age 5), they're likely to have fewer problems, be less prone to hyperactivity disorders and have higher cognitive test scores. See "Light Drinking During Pregnancy: Still No Increased Risk for Socioemotional Difficulties or Cognitive Deficits at 5 Years of Age?"
There's no doubt that chronic binge drinking during pregnancy can do lasting harm to a woman's fetus. Similarly, there's no doubt that roasting yourself in the sun all summer and continuing to irradiate yourself in a tanning bed the rest of the year can lead to malignant melanoma. Yet extrapolating from such findings to declare that there's no safe level of exposure to sun or alcohol or whatever not merely panics parents needlessly; it may well result in the infliction of needless harm on the very people for whose benefit such advocacy is intended.
