Tylenol and Autism?

In The Politics of Autism, I discuss various ideas about what causes the condition.

Here is just a partial list of correlates, risk factors, and possible causes that have been the subject of serious studies:

• Pesticides;
• Air pollution and proximity to freeways;
• Maternal thyroid issues;
• Autoimmune disorders;
• Induced labor;
• Preterm birth;
• Birth by cesarean section;
• Maternal and paternal obesity;
• Maternal and paternal age;
• Maternal post-traumatic stress disorder;
• Smoking during pregnancy;
• Antidepressant use during pregnancy. 

A release at Medical Express describes a study fingering the active ingredient in Tylenol:

A new study has found that paracetamol (acetaminophen), which is used extensively during pregnancy, has a strong association with autism spectrum symptoms in boys and for both genders in relation to attention-related and hyperactivity symptoms.

The findings were published this week in the International Journal of Epidemiology. This is the first study of its kind to report an independent association between the use of this drug in pregnancy and autism spectrum symptoms in children. It is also the first study to report different effects on boys and girls. Comparing persistently to nonexposed children, the study has found an increase of 30 per cent in the risk of detriment to some attention functions, and an increase of two clinical symptoms of autism spectrum symptoms in boys.

Speculation about a Tylenol-autism link has been around for years.  At The Independent, however, May Bulman reports that skepticism is in order:

[The] director of science at autism charity Autistica, Dr James Cusack, insisted there was “not sufficient evidence” to back the suggestion.

He said: “This paper does not provide sufficient evidence to support the claim that there is a strong association between paracetamol use and the presentation of symptoms of autism. The results presented are preliminary in their nature, and so should not concern families or pregnant women." 

... He added that there had been "an array of environmental factors which have been associated with autism, only to be rejected later", emphasising the importance of collecting sufficient evidence before making such claims.