Lead Exposure May Have Lowered The IQ of Half of Americans Since 1940

Lead Exposure May Have Lowered The IQ of Half of Americans Since 1940. By Carly Cassella.

Childhood lead exposure in the United States is ubiquitous and much more concerning than previous estimates have suggested, according to a new study.

When researchers analyzed leaded gas use from 1940 and combined it with data on blood-lead levels from the mid 1970s, they found more than 54 percent of Americans alive in 2015 had been exposed to dangerous levels of lead as children.

That’s more than 170 million adults who are now at greater risk of neurodegenerative disease, mental illness and cardiovascular issues, because of the lead they breathed in, ingested or absorbed as kids.

No level of lead exposure is safe at any point in a person’s life, but this highly toxic metal can be especially detrimental for children as it can impede brain development, leading to permanent learning difficulties and behavioral issues.

Altogether, researchers estimate leaded gas has reduced the nation’s cumulative IQ score by 824 million points, which [averages] nearly three points per person.

And that’s just the average. Those born in the 1960s and 1970s, when leaded gas use was reaching a peak, could have lost an average of six to seven IQ points. The cohort’s lead exposure was eight times over today’s health limits.

Ever since the US government banned leaded gasoline for cars in 1996, childhood lead exposure has gradually fallen. Yet there are still many Americans alive today who are dealing with the fallout of their upbringing.

Children born after 1996 generally have lower blood-lead levels than their parents and grandparents, but compared to generations before the preindustrial era, their lead exposure is still much higher. …

Lead poisoning is insidious by nature. The invisible and odorless pollutant has historically been used in paints, pipes, and gasoline, and even though restrictions are better than they once were, at least in the US, enormous quantities of lead have already seeped into our drinking water, our airways, and our homes.

Leaded gas from car exhaust may no longer be the threat it once was, but other sources of lead pollution, like hunting ammunition, plumbing and industrial waste, still pose a threat to humans and the wider environment.

Same for the rest of the West, of course. The evidence that average IQ in the West is falling is overwhelming. I’d guess that this cause ranks behind feminism urging brighter women to have careers rather than families (the only IQ cohorts at or above replacement rate are those whose average IQs are 80 or below).