The cruel irony in the latest news on lead's lifelong effects on kids

Earlier this week, many media outlets reported on a new study in JAMA that found lead had negative effects on IQ and social mobility that were evident several decades after the toxin was first detected in the blood of 11-year-old New Zealanders.

There are a few things that make this study notable and garnered headlines. One is that it looked at lead’s effects over a far longer period of time than previous studies — up to age 38. Second, the study focused on whether blood levels in childhood were tied to IQ and socioeconomic status later in life — both of these measures declined more in those with higher levels of lead poisoning.

But one of the cleverest things about the research is the way it gets around the tricky question of poverty. By drawing on data from a long-running study of individuals born in Dunedin, New Zealand in 1972-73, researchers were able to look at how lead poisoning works across class lines, since airborne emissions from the heavily leaded gasoline prevalent in New Zealand at the time didn’t discriminate. Had the researchers instead only focused on poorer children, typically more likely to be exposed to lead, it would’ve been far more difficult to untangle whether the drops in IQ or mobility were the byproduct of lead or something else that comes with being poor. 

Among the 565 individuals the study tracked, researchers found consistent links between blood lead levels and IQ, and blood lead level and socioeconomic status as adults. For each additional five micrograms of lead per deciliter of blood registered at age 11, adult IQ dropped about 1.6 points. These patterns held true regardless of their social class, mothers’ IQ, or even the subjects’ own IQ as children. The effect on IQ was about the same as low birth weight. The researchers write:

Despite being mild, the cognitive decline evident among lead-exposed children was accompanied by altered socioeconomic life trajectories, measurable as small but detectable downward social mobility by midlife for the most-exposed children regardless of their origins.

While lead may have been an equal-opportunity offender in 1970s New Zealand, it’s a different story in the U.S. today, where poorer children are far more likely to be exposed to lead through old housing and water systems. The cruel irony is that the kids most likely to be exposed to lead poisoning are already much more likely to be mired in poverty. In other words, poor kids already face an uphill climb out of poverty; lead is like a downward shove for kids already struggling to pull themselves up. But unlike a one-time shove, lead’s effects never dissipate. Instead, as this latest study suggests, they get worse. 

That means that the challenge of breaking the cycle of poverty for many kids isn’t just a question of expanding economic opportunities, improving education or targeted interventions — no such gains can correct for lead’s debilitating impact on developing brains.

“Children will continue to experience the greatest harm from lead exposure, and disadvantaged children will bear a disproportionate share of the burden,” writes David C. Bellinger, a professor of environmental health at Harvard, in an editorial accompanying the JAMA study. The burden’s longevity means prevention is king.

Childhood lead poisoning can feel like a very old-fashioned problem that forgot to take its place in history. It doesn’t have the newsy buzz or heart-wrenching photos that accompany Zika, nor does it ride a wave of new research and foundation funding that has thrust toxic stress and childhood adversity into the limelight. That can make it hard to marshal the political capital needed to step up prevention, screening and cleanup efforts.

But if there’s a bright spot in the ongoing crisis of children being poisoned, it’s the renaissance in ambitious journalism that has turned a sleeping problem into a living outrage. From single-city deep dives in Cleveland to Philadelphia to broader data-driven investigative work from Reuters and USA Today, journalists have repeatedly sounded the bell on lead’s danger in recent years.

There are early signs that policymakers are increasingly taking notice. Whether that notice translates into on-the-ground investments that outlast the most recent barrage of negative headlines is a story worth tracking wherever lead is still found. Unfortunately, that’s almost everywhere.

[Cropped photo by Melissa Hillier via Flickr.]