Doctors from the Mount Sinai Children's Environmental Health Centre in New York are calling for renewed efforts to examine the role of toxic chemicals in causing autism and other neurodevelopmental disorders, like ADD/ADHD.
While the causes of autism remain unknown, most researchers suspect a combination of genetic and environmental factors are responsible. Health professionals estimate that 3 per cent of neurobehavioral disorders are caused directly by exposure to toxic chemicals, and that another 25 per cent can be blamed on interactions between environmental and genetic factors, said an editorial published yesterday in the journal Environmental Health Perspectives.
"A great concern is that a large number of the chemicals in widest use have not undergone even minimal assessment of potential toxicity, and only about 20 per cent have been screened for potential toxicity during early development," writes Mount Sinai Children's Environmental Health Center director Philip Landrigan.
"Knowledge of environmental causes of neurodevelopmental disorders is critically important because they are potentially preventable," they added in a press release coinciding with the published editorial.
In December 2010, the Children’s Environmental Health Center hosted a symposium called “Exploring the Environmental Causes of Autism and Learning Disabilities.” Co-sponsored by the autism advocacy group Autism Speaks and the National Institute of Environmental Health Sciences, the workshop's goal was to discover preventable environmental causes of autism and other neurodevelopmental disorders. The gathering also developed a list of 10 chemical/environmental suspects:
The Terrible 10
Lead
Found in paint, dust, drinking water, some canned imported food, older toys, some imported toys, lead-glazed or lead-painted pottery, and some inks.
Methylmercury
Methylmercury is not the same as ethylmercury, the form found in Thimerosal, the controversial preservative formerly used in vaccines and which some believe is linked to autism. Methylmercury is released into air and water mostly from industrial emissions. It is the form of mercury that is found in high concentrations in some fish.
PCBs
The U.S. government banned production of PCBs in 1977, but they continue to be released into the environment from hazardous waste sites and from illegal or improper dumping. PCBs are also found in some types of caulk used in building materials, including in some schools.
Organophosphate Pesticides
These make up the majority of pesticides used on fruits and vegetables ingested by pregnant women and kids in the United States.
Organochlorine Pesticides
Less common, organochlorines are still used. The most infamous organochlorine is DDT, which was fully banned in the United States in 1972.
Endocrine Disruptors
Endocrine disruptors are chemicals that can potentially interfere with prenatal development. There are literally hundreds of endocrine disruptors, the most well-known of which is bisphenol-A, or BPA.
Automotive Exhaust
Toxins of concern in motor vehicle exhaust include carbon monoxide, nitrogen dioxide, and sulphur dioxide.
Polycyclic aromatic hydrocarbons
These chemicals are found in an array of sources — from cigarette smoke and burning coal to industrial waste incineration and hazardous waste sites.
Brominated Flame Retardants
These fireproofing chemicals are added to pillows, vehicle seats, fabrics, and some electronics — including computers.
Perfluorinated Compounds
PFCs are found in sources as varied as water-resistant clothing, some non-stick cookware, and microwave popcorn bags.