Research Spotlight: Safe Until Proven Otherwise: The Manifold Consequences of Leaded Gasoline

The legal thriller Dark Waters (2019) staring Mark Ruffalo follows the recent real-life story of Robert Bilot, an environmental corporate lawyer turned environmental advocate. In it, Bilot seeks accountability from Dupont corporation for contaminating Parkersburg, West Virginia with the noxious yet unregulated chemical PFOA — a key component of Teflon and cause of cancer and other physical maladies. A key yet disheartening message from this tale is that most chemicals are not regulated by the EPA, or any other government agency, and the companies that profit from their use determine when a chemical should be regulated (based on their toxicity). This film presents an apt example of how society deals with toxicants: namely, treat them as safe until proven unsafe. Like in the movie, proving a profitable chemical unsafe means contending with possibly biased and definitely well-funded science from financial juggernauts like Dupont (market cap of $35.88 billion). This presumption is not limited to PFOA or this case, rather it might as well form the basis for environmental health policy in the US. There is no better example of this than that of leaded gasoline which didn’t just harm a small city but —as our research shows— half of our country.

Lead is the world’s most well-known neurotoxicant and has been used for thousands of years. The ancient Romans wrote extensively about its effects. You would have thought someone would have questioned whether adding lead to gasoline and thereby flooding our atmosphere was a bad idea. Turns out, researchers did, circa 1921 when lead was first proposed as a gasoline additive, but they were largely ignored by General Motors (GM) — the original company behind its fuel use. GM disregarded, buried, and later engaged in a scientific distortion campaign to discredit such knowledge. Lead was added to gasoline to make it burn more smoothly but it was not the only option, it was the most profitable one. After a flurry of initial concern, the inclusion of lead in gasoline persisted for over fifty years without any scientific, legal, or regulatory challenges. Independent research eventually emerged and was damning enough to lead to a world-wide phase out of leaded gasoline despite obstinance from the corporate giants GM, DuPont, and Ethyl Corporation. Notwithstanding the scientific consensus that leaded gasoline did irreparable harm to young children, we had, until now, a very incomplete understanding of the scope of the worst public health disaster in US history.

Some exposure to lead in the days of leaded gasoline was inevitable. You pump the atmosphere with a compound and people get exposed. It was inhaled along roadways and deposited in soils and water supplies. This was well known—at least to those paying attention. What wasn’t known until know was the likely full extent of that exposure. How many people were exposed and to what degree? That’s what my colleagues and I investigated in our recent article. Using several sources of data, including that on leaded gasoline consumption, we estimated that over one-half of the US population was exposed to adverse lead levels in early childhood—when lead appears to do the most harm. In fact, high exposures (over two times the current reference value) were nearly universal among those born between 1951-1980. Moreover, not only were a prodigious number of children exposed, but large numbers were also exposed to what are now considered very high levels. For instance, seven percent of children were exposed to lead levels that were at least six times higher than the current reference level.

The roughly 170 million of yesterday’s children exposed to adverse lead levels are still with us – adults now in their 30s, 40s, and 50s – and the consequences of these exposures will continue on. These “legacy lead exposures” likely experienced subtle deficits in important outcomes, such as cognitive ability, fine motor skills, and emotional regulation, that may have influenced their lives in areas such as educational attainment, health, wealth, and happiness. Our study quantified the consequences of exposure for one such outcome: cognitive ability. Average loses in IQ points ranged from 2 to 6 points per person. These are not trivial loses for individuals nor society. For instance, economists have estimated that a single IQ point is worth more than $10,000 in lifetime earnings. At the level of society, 2-6 IQ points per person is extraordinarily meaningful, as it lowers overall productivity, decreases the number of geniuses, and increases the number of folks with cognitive impairment who require greater social support.

By documenting the widespread consequences of lead exposure, our study underscores the folly in “safe until proven unsafe” thinking. Unfortunately, we continue to employ this flawed premise in our regulatory policy. For instance, a current concern in the US is the continued use of leaded gasoline in prop-airplanes. A petition is before the EPA to finally remove lead from all gasoline, while researchers are trying to determine the likely detrimental outcomes currently experienced by children living adjacent to small airports. This research is used by public health advocates, journalists, politicians, and others to try and protect communities that live near airports. Our work suggests the onus should be on those using, producing, and selling such fuel to show it’s not harmful– not the other way around.

We determined that the consequences of the utilization of leaded gasoline are prolific nearly three decades after its use was banned. While the US eventually prohibited its use and decreased lead exposure considerably, it’s too late for half the US population. They may never know how lead impacted them, but it likely did. The fact that it took from 1923-1996 to prohibit leaded-gasoline use points to the assertion I made at the beginning of this blog: environmental exposures are considered safe until proven otherwise. Going forward we have the opportunity to uproot this type of thinking and start favoring people over ideologies. Profit seeking should not outweigh public health. The environment doesn’t belong to anyone. The only way to protect it is to shield it from such thinking and the pernicious consequences that arise.

The research discussed in this piece was published in the Proceedings for the National Academy of Sciences (PNAS). I thank Matt Hauer, Cheryl McFarland, and Aaron Reuben for comments on previous drafts.

Matthew McFarland is an Associate Professor of Sociology at FSU. His research interests include health disparities, biodemography, and mental health. You can learn more about Dr. McFarland here.

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