The Reduction in the Age-Adjusted Prevalence of Hearing Impairment in the United States An Unexpected Dividend of Phasing Out Leaded Gasoline?

In their article, "Declining Prevalence of Hearing Loss in US Adults Aged 20 to 69 Years," Hoffman and colleagues concluded that there was a 25% reduction in high-frequency hearing impairment and a 30% reduction in speech frequency hearing impairment in respondents' worse ear between the 1999 to 2004 cycle of the National Health and Nutrition Examination Survey (NHANES) and the 2011 to 2012 NHANES cycle. I hypothesize that this beneficial trend may be partially owing to the phasing out of leaded gasoline which resulted in an 87% decline in the geometric mean blood lead levels (BLL) in American adults from 13.1 μg/dL in the late 1970s to 1.64 μg/dL by the year 2000.

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