Is autism caused by fetal exposure to environmental toxins?

Coal power plant emissions.
(Riedel/AP)

New York Times columnist Nicholas Kristof writes:

Over recent decades, (autism and) other development disorders...appear to have proliferated, along with certain cancers in children and adults.

(O)ne culprit may be chemicals in the environment.

Kristof cites an article by Dr. Philip J. Landrigan, professor of pediatrics at the Mount Sinai School of Medicine in New York and chairman of the school’s department of preventive medicine.From Dr. Landrigan's abstract:

Genetic factors – mutations, deletions, and copy number variants – are clearly implicated in causation of autism. However, they account for only a small fraction of cases, and do not easily explain key clinical and epidemiological features. This suggests that early environmental exposures also contribute.

Indirect evidence for an environmental contribution to autism comes from studies demonstrating the sensitivity of the developing brain to external exposures such as lead, ethyl alcohol and methyl mercury.

But the most powerful proof-of-concept evidence derives from studies specifically linking autism to exposures in early pregnancy – thalidomide, misoprostol, and valproic acid; maternal rubella infection; and the organophosphate insecticide, chlorpyrifos. There is no credible evidence that vaccines cause autism.

One of the most significant environmental sources of methyl mercury is from burning coal for electric power generation.

As Dr. Landrigan's suggests,  a reduction in pollution may decrease fetal exposure to environmental toxins that may be causing developmental disabilities including autism spectrum disorders.

With climate change dominating the environmental debate, that benefit seems at times forgotten.