PCBs were banned in the '70s, but not before they had already done their damage. They're linked to problems with the brain, nervous and hormone systems, and although average levels in the human body have dropped, human exposure continues. See, PCBs are persistent contaminants, which means they build up in the environment and in us.
Evidence continues to build that PCBs also affect birth sex. A recent study of blood serum from women who were pregnant in San Francisco in the '60s found that those with higher PCB levels were more likely to give birth to boys than those with low PBC levels. The study puts another nail in the coffin for PCBs, but Dr. Pete Myers brings up an important point in his summary of the report:
The exposure levels observed in the study are high compared to today. Thus if these results are indicative of a causal relationship (never possible to confirm with epidemiological studies) then the simplest prediction would be that the chances of having a boy baby should be increasing because PCBs have been decreasing. That is not the case, at least as of the most recent analysis from Canada and the US.He's right. Evidence from a large-scale study of four industrialized nations indicates that the sex ratio is skewed, and fewer boys are being born -- and, since PCB levels have dropped, we probably can't blame it on that.
But we can look to PCBs as evidence that in-utero exposure to pollutants can affect a child's sex. There are more than 80,000 chemicals in production today, many of which are known to be persistent or to disrupt hormone systems, and most of which haven't really tested for their impact on human health. And you know what? By the time we get around to cleaning up those culprits, they will have done their damage, too.
How many times must history repeat itself before we get our act together and demand that chemical companies put people before profits?
Photo by Erik R. Bishoff.