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Toxic Threats to Brain Development

Chemicals and Categories of Chemicals Known to Harm Brain Development

Approximately 3,000 chemicals are produced at more than one million pounds per year. Of these 3,000 chemicals, scientists have determined with certainty that 10 to 12 chemicals or categories of chemicals are developmental neurotoxins--they can interfere with brain development. There is good evidence that another 200 of these chemicals are neurotoxins in adults. However, because the vast majority of chemicals do not have to be tested for health effects before being used in products, we have very little information on their potential to harm the developing brain.

Two of the most well-known neurotoxins are alcohol and nicotine. Fetal Alcohol Syndrome, now considered part of Fetal Alcohol Spectrum Disorder, is the most preventable form of behavioral and learning disabilities. Smoking during pregnancy and exposure to secondhand smoke are also preventable causes of behavioral disorders and developmental delays.

Chemicals Known to Harm Brain Development

• Lead: Found in old paint in older houses and buildings, also found in toys, jewelry, lead pipes and lead sinkers. There is no safe level of lead exposure for children.
• Mercury: Released into air from coal-fired power plants, also found in medical equipment, switches and fluorescent bulbs. Mercury falls into the water, where it accumulates in fish. The main source of exposure for people is through eating fish.
• PAHS: Air pollutants from fuel combustion in vehicles, coal-fired power plants, heating and cooking. These air pollutants are also found in tobacco smoke.
• PCBs: Used to make electrical transformers. Banned in the late 1970s, but persistent in the environment and still widely found in lakes, rivers, soil, fish and people.
• PBDEs: Certain flame retardants added to furniture, electronics, clothing and other products. PBDEs accumulate in household dust and have been found in breastmilk. The states of Washington and Maine have banned all PBDE flame retardants.
• Manganese: A trace element that at high levels, either in drinking water or through exposure to welding fumes, can damage brain development.
• Arsenic: Found in drinking water around the world, arsenic affects neurodevelopment in children.
• Pesticides: Used to kill insects,plants, fungi or animals on crops, lawns, homes, schools and office buildings. U.S. pesticide use in agriculture and homes totals more than one billion pounds per year.
• Solvents: An array of compounds,including toluene, benzene, alcohol, turpentine, acetone and TCE, found in products such as gasoline, lighter fluid, lubricating oils, paint strippers and thinners, glues, polishes, cleaners, stains and shellacs.

Chemicals Under Investigation for Effects on Brain Development

• Bisphenol A (BPA): A plasticizer that mimics estrogen in the body, BPA is found in hard plastics, food and soda can linings, and cash register receipts, among other uses.
• Food Additives (Dyes and Preservatives): Used throughout the food supply and long suspected of causing conduct disorders and hyperactivity. Under study for effects on neurodevelopment, cognition and behavior.
• Fluoride: Commonly added to municipal drinking water and in toothpaste and mouthwashes. Excessive fluoride lowers thyroid hormone levels. Primary concerns are cumulative exposures and determining levels that may affect neurodevelopment.

For more information on chemicals that can harm brain development and function, see “Scientific Consensus Statement,” published by the Learning and Developmental Disabilities Initiative (LDDI) Working Group of The Collaborative on Health and the Environment (CHE).