Vaccines have already been eliminated as a cause of autism, but prenatal mercury exposure has still been suspected as a cause of the condition. Expecting mothers have been warned away from eating fish during pregnancy over fears of developmental problems. A new study this week calls into question the mercury-autism connection, showing no link between mercury exposure and autism-like behaviors.
The study, published this week in the journal Epidemiology, looked at people living in the Republic of Seychelles. The Indian Ocean island nation has a population of around 87,000 people who consume fish as a primary source of nutrition - as much as 10 times the fish consumed by people in the U.S. and Europe. The Seychelles Child Development Study began in the 1980s to study the impact of fish consumption and mercury exposure in children.
"The Seychelles study was designed to follow a population over a very long period of time and focus on relevant mercury exposure," said Philip Davidson, principal investigator of the Seychelles Child Development Study and a pediatrics professor at the University of Rochester Medical Center. "While the amount of fish consumed in the Seychelles is significantly higher than other countries in the industrialized world, it is still considered low level exposure."
Researchers were able to determine prenatal mercury exposure levels through hair samples of the mothers of 1,784 children and young adults. The children and their parents were then given questionnaires designed to surface autism-like behaviors.
The study found no correlation between prenatal mercury exposure and autism-like behavior. The study's authors believe their results suggest that fish consumption during pregnancy may not be as dangerous as currently thought. They suggest that the nutritional benefits of fish "may counteract or perhaps even supersede the potential negative effects" of mercury exposure.
"This study shows no consistent association in children with mothers with mercury levels that were six to ten times higher than those found in the U.S. and Europe," said Davidson. "This is a sentinel population and if it does not exist here than it probably does not exist."