Can heavy metal exposure during pregnancy increase autism traits in children?

What's actually in it

Pregnant people absorb lead from old paint dust and tap water, mercury from fish (especially tuna and swordfish), cadmium from rice and vegetables, and arsenic from water and rice. These heavy metals cross the placenta and reach the developing baby's brain during the most sensitive period of growth.

Unlike many chemicals that leave the body fairly quickly, metals can persist in bone and brain tissue for years.

What the research says

A 2026 prospective study in Environ Int measured heavy metal levels in pregnant women and then tracked their children's autistic traits over several years. Unlike studies that measure traits at a single point, this one followed the trajectory, how traits changed as children grew.

Children with higher prenatal exposure to lead and mercury showed a steeper increase in autistic traits over time. They didn't just start higher. The gap between them and less-exposed children widened with age. This suggests the metals caused developmental changes that compound over time.

Cadmium exposure showed similar but weaker associations. The combination of multiple metals produced a stronger effect than any single metal, pointing to a mixture effect.

Reducing metal exposure during pregnancy can help. Filter your drinking water (especially if you have old pipes), limit high-mercury fish to once a week, rinse rice before cooking with extra water, and keep floors clean in older homes where lead paint dust may be present.