15 February 2014. An article just published in The Lancet Neurology is calling on countries worldwide to transform their chemical risk-assessment procedures in order to protect children from everyday toxicants that appear to cause a global “silent epidemic” of brain development disorders. The article focuses on the most recent evidence as a follow-up of a previous Lancet review.
The 2006 Lancet review suggested that exposure to brain-toxic chemicals was causing a global pandemic of neurobehavioral deficits, including diagnoses, such as autism, ADHD, and dyslexia. Only a handful of chemicals was considered known to cause developmental toxicity in 2006: lead, methylmercury, arsenic, toluene, and PCB. If alcohol (ethanol) is also counted as an industrial chemical, that makes 6. From descriptions of poisoning cases, a total of 201 industrial chemicals were known at the time to be capable of causing brain toxicity in humans – almost all of that evidence refers to adults. Despite the developing brain being inherently much more vulnerable, the scientific documentation of chemical brain drain was clearly lagging behind. The article raised much attention and has since then been cited in more than 450 other scientific articles.
Given the incomplete evidence, has there been any improvement since 2006? According to the updated review, the number of chemicals that can cause harm to children’s brains has now doubled. The six new compounds are: manganese, fluoride, chlorpyrifos and DDT (pesticides), tetrachloroethylene (a solvent), and the polybrominated diphenyl ethers (flame retardants).
However, at the same time, the list of chemicals that are known to damage the human brain (in adults) has expanded to 214, an even greater increase. A complete list of these substances is available here. Thus, the documentation on toxicity to developing brains is lagging further behind. Waiting for epidemiological studies on children to provide the desirable documentation is therefore not a viable strategy – too many children, in fact generations of children, will be exposed to too many chemical brain drainers before the magnitude of the problem can be documented in detail.
Controlling the global epidemic of chemical brain drain is virtually impossible because of the scarcity of data to guide prevention and the huge amount of proof needed for government regulation. So far, very few chemicals have been regulated as a result of developmental neurotoxicity. The problem is international in scope, and the solution must therefore also be international. Methods are already in place to test industrial chemicals for harmful effects on children’s brain development. Now is the time to make that testing mandatory.
Comments on the study were published by, e.g., CNN, USAToday, and Huffington Post.