Low-Level Lead Didn't Affect Preemie Hearing Nerves (Yet)
NonToxCo Research
Science & Safety Team · 4/7/2026
Good news with a caveat. In premature babies, very low lead levels in cord blood didn't damage the nerves responsible for hearing. But that doesn't mean lead is safe.
What the Study Found
A 2026 study in Early Hum Dev tested 103 premature infants born at 33 weeks or earlier. Cord blood lead levels averaged 0.54 µg/dL (range: 0.065 to 5.30). Researchers used auditory brainstem response testing at 35 weeks to measure auditory neural myelination (how well the hearing nerve insulation was developing).
No association was found between cord blood lead and auditory nerve function at these low levels.
Why This Doesn't Mean Lead Is Safe
The lead levels in this study were very low, averaging well under 1 µg/dL. The CDC considers 3.5 µg/dL the reference value for action. Previous studies in full-term infants with higher exposure did find auditory nerve damage. The question isn't whether lead harms developing brains. It does. The question is whether the very lowest levels affect this specific nerve pathway in preemies.
The study also only measured one time point (35 weeks). Longer-term effects on hearing and brain development may still emerge.
The Bigger Picture
No blood lead level is considered safe. Even levels below the CDC threshold have been linked to IQ drops, behavioral problems, and learning disabilities. Premature babies are especially vulnerable because their brains are still developing rapidly.
How to Protect Your Baby
Test for lead in your home, especially in pre-1978 housing. Filter drinking water. Get blood lead tested during pregnancy. Check out non-toxic baby products for lead-free options.
Also see glass food storage for safer alternatives.