Lead and Minor Hearing Impairment

TLDR

The study aimed to confirm that higher blood lead levels are linked to elevated hearing thresholds in children, extending previous findings from NHANES. The authors analyzed data from 3,545 Hispanic children aged 6–19 years in the Hispanic Health and Nutrition Survey. Higher blood lead levels were linked to worse hearing thresholds across all tested frequencies, with a 2‑dB loss per 6‑18 µg/dl increase and a 15% rise in children below the standard at 2 kHz, effects persisting even at levels below 10 µg/dl.

Abstract

We examined data recorded for 3,545 subjects aged 6-19 y who participated in the Hispanic Health and Nutrition Survey. We sought to confirm a relationship between blood lead levels and elevated hearing thresholds that we previously reported in a similar study in which data from the Second National Health and Nutrition Examination Survey was used. Lead was associated with an increased risk of hearing thresholds that were elevated above the standard reference level at all four frequencies (i.e., 500 Hz, 1,000 Hz, 2,000 Hz, and 4,000 Hz). Lead was also associated with hearing thresholds when they were treated as a continuous outcome. The relationships appeared to continue at blood lead levels less than 10 micrograms/dl. An increase in blood lead, from 6 micrograms/dl to 18 micrograms/dl, was associated with a 2-dB loss in hearing at all frequencies, and an additional 15% of children had hearing thresholds that were below the standard at 2,000 Hz.