Deborah Blum at Speakeasy Science has put up a terrific two-part post about the early history of leaded gasoline, which bears much of the blame for lead poisoning in workers and the general population. (Paint containing lead is the other main culprit.) Blum’s “At the Door of the Loony Gas Building” and “Of Dead Bodies and Dirty Streets” involve plot developments that might sound familiar: product kills people, industry insists product is safe, and back-and-forth about product’s safety continues for decades before the product is finally altered, eliminated, or restricted to reduce harm to public health.
In the US, there’s some good news at the end of the story, although it’s not entirely happily-ever-after.
Sales of leaded gasoline started dropping off in the mid-1970s, after EPA set emissions regulations that prompted car companies to turn to catalytic converters, which don’t work well with leaded fuel. Researchers from CDC’s National Center for Environmental Health and Harvard University’s School of Public Health studied the decline in blood lead levels between 1976 and 1999 and calculated what the BLL drop meant for IQs. Here’s what they found:
These calculations imply that, because of falling BLLs, U.S. preschool-aged children in the late 1990s had IQs that were, on average, 2.2-4.7 points higher than they would have been if they had the blood lead distribution observed among U.S. preschool-aged children in the late 1970s. We estimated that each IQ point raises worker productivity 1.76-2.38%. With discounted lifetime earnings of $723,300 for each 2-year-old in 2000 dollars, the estimated economic benefit for each year’s cohort of 3.8 million 2-year-old children ranges from $110 billion to $319 billion.
While this is something to cheer, it’s also frustrating that widespread lead poisoning continued for so long after the 1920s, when lead’s role as a neurotoxi
ncant was well known. The continued use of lead well into the 20th century not only affected those who suffered its harmful effects during that time period, but allowed for the buildup of contamination that’s still affecting children today. CDC reports, “Approximately 250,000 U.S. children aged 1-5 years have blood lead levels greater than 10 micrograms of lead per deciliter of blood, the level at which CDC recommends public health actions be initiated.” Old, peeling paint and contaminated dust are the main sources of exposure today, and many cities (particularly those with older housing stocks) find it difficult to fund the rehabilitation that would further reduce lead exposure.
The profits from the continued sale of leaded gasoline were concentrated among a small group of people, but the costs were spread across the population. The oil refinery workers described in Blum’s pieces, who were severely — in some cases, fatally — poisoned, paid the most dearly. Lead-poisoned children and their families have borne the burdens related to learning and behavior problems. The US as a whole has lost billions of dollars worth of worker productivity.
Lead might seem like a closed chapter in US history, but that’s not the case at the global level. In many developing countries without regulatory systems that effectively limit lead exposures, the costs of lead poisoning are mounting.