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In the early 20th century, as cars were beginning to be popular in the United States, lead was first added to petrol to help keep car engines healthy. However, a recent study calculates that exposure to car exhaust from leaded gas during childhood stole a collective 824 million IQ points from more than 170 million Americans alive today, about half the population of the United States.
Lead in cars was banned in the US in 1996, but as a consequence, Americans born before 1996 may now be at greater risk for lead-related health problems as several had worryingly high lead exposures as children. Lead is neurotoxic and can erode brain cells after it enters the body. As such, there is no safe level of exposure at any point in life, health experts say. Young children are especially vulnerable to lead’s ability to impair brain development and lower cognitive ability. Unfortunately, no matter what age, our brains are ill-equipped for keeping it at bay.
Lead is able to reach the bloodstream once it’s inhaled as dust, or ingested, or consumed in water and is able to pass through the blood-brain barrier, which otherwise, effectively keeps out a lot of toxicants and pathogens out of the brain, but not all of them. The researchers determined this relationship using publicly available data on US childhood blood-lead levels, leaded-gas use, and population statistics, they determined the likely lifelong burden of lead exposure carried by every American alive in 2015. From this data, they estimated lead’s assault on our intelligence by calculating IQ points lost from leaded gas exposure as a proxy for its harmful impact on public health.
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