A new study suggests that there may be a possible link between lead exposure and hearing loss in teens.
Exposure to heavy metals have long been suspected of causing hearing loss, but a new study conducted by researchers from Massachusetts found that some teens exposed to levels of lead far below current safety standards later experienced trouble hearing. Researchers could find no similar association with several other heavy metals.
The study, published in the Archives of Otolaryngology – Head & Neck Surgery, looked at levels of lead and mercury in the blood, as well as cadmium and arsenic in the urine, of 2,500 teens aged 12 to 19. They then compared those levels with rates of hearing loss.
Researchers found that teens exposed to very low levels of lead had a higher chance of suffering high-frequency hearing loss. There was also a small possible association with cadmium exposure, but researchers said those findings were suspect.
Hearing loss occurred in teens exposed to only 2 micrograms per deciliter, well below the 10 micrograms per deciliter considered safe. However, researchers pointed out that the study does not make a clear causal link proving that the lead exposure is what caused the hearing loss, and only a small number of teens exposed suffered degraded hearing.
One of the more common causes of lead exposure in the United States is lead paint, which was banned in 1978 due to the risk of severe and permanent brain damage and developmental problems, particularly in children. However, a number of older homes still contain the toxic paint on the walls, and if it flakes or peals off, young children could ingest the paint chips or breathe dust that comes from the paint, resulting in lead poisoning.
Lead poisoning can result in nervous system injury, brain damage, seizures or convulsions, growth or mental retardation, coma and even death for young children. The U.S. Centers for Disease Control and Prevention (CDC) consider 10 milligrams of lead per deciliter of blood to be the level of concern for exposure to lead. The CDC estimates that approximately 250,000 children in the U.S. have blood lead levels that high or higher.