We’ve all heard that ingesting lead paint chips is bad for children and that pregnant women need to be careful about what type of fish they eat, but did you know there are at least 11 chemicals scientists think may have major effects on our brains, especially as they’re developing? As researchers dig into the dangers of certain common (or formerly common) chemicals used in a wide array of products, they’re uncovering links to brain health, including changes in mental abilities and behavior.
In 2006, Philip Landrigan, a doctor from the Icahn School of Medicine at Mount Sinai in New York, and Philippe Grandjean, a doctor from Harvard School of Public Health in Boston, published an article in the journal The Lancet sounding the alarm about five chemicals believed to affect the mental development of infants and small children. In February 2014, they published a follow-up article in The Lancet Neurology with six more. Together, that’s 11 chemicals thought to affect the brain development of children, with effects including lower scores on tests of intelligence, memory and attention; poorer performance in school; and in many cases behavior problems. The researchers hypothesize that the rise in neurodevelopmental disabilities including autism, attention-deficit hyperactivity disorder (ADHD), dyslexia and other cognitive impairments may be linked to early exposure to these chemicals.
We’ll get into what these chemicals are and how best to avoid them, but first, why the focus on children? Children are especially vulnerable to chemicals for several reasons: For one, their defenses to toxins aren’t fully developed yet. The blood-brain barrier that keeps many chemicals from entering our brains isn’t fully formed until we’re about 6 months old. Chemicals can also hit children at crucial windows of mental and physical development. In many cases, exposures to chemicals as infants or even while in the womb can affect people for the rest of their lives. Simply put, children need greater protection from these chemicals than adults do (although in larger doses they affect adults, too). While the majority of us may not be pregnant or have a young infant, it’s wise to learn about these chemicals, where they appear in our environments and how they can affect our brains and behavior.
How are we exposed to it? Although lead paint hasn’t been sold since 1978, it’s still found in many older homes. Lead can also be found in older plumbing and in a variety of products including colorful ceramics (it’s sometimes used in the paint), inexpensive children’s toys, and even lipstick (a recent study found traces of lead in most lipsticks, along with aluminum, chromium and manganese in many others). People who do a lot of home remodeling as an occupation or hobby may be exposed to lead more often.
Health effects: Lead has well-documented cognitive effects in children who are exposed, causing a lowered ability to learn. In adults, high levels of lead are linked to brain and nervous system damage; hearing, vision and muscle coordination problems; and a variety of other issues, including high blood pressure, kidney problems and impotency. There is no indication that any level of lead exposure is safe.
Tips for dealing with it: The EPA recommends keeping painted areas in good condition to decrease lead exposure—if you believe you have lead-based paint in your home, paint over it or contact a lead abatement professional. You should also consider replacing lead-containing plumbing fixtures, which are a potential issue if you have nonplastic plumbing installed before 1986. You can buy drinking water lead-testing kits in home-improvement stores. Learn more.
Also known as: Polybrominated diphenyl ethers
How are we exposed to them? PBDEs have not been manufactured in the U.S. since 2005; before then they were widely used as flame retardants in upholstered furniture, carpets, rugs and electronics. Products with PBDEs were not labeled. PBDEs don’t readily break down, and they contaminate land, water and animals. Some PBDEs can build up in fish and mammals.
Health effects: Research suggests PBDEs affect the thyroid and liver in addition to brain development. In a study investigating the impacts of flame retardants, 309 pregnant women had their PBDE blood levels tested. Spikes in PBDE levels correlated with behavior and cognition difficulties during early childhood.
Tips for dealing with them: Replacing furniture hasn’t been advised as new products often have different toxic flame retardants. New regulations in California starting in 2014 allow sales of products without flame retardants (a 2012 investigative series by the Chicago Tribune found flame retardants provide no meaningful fire protection). Other precautions: Keep furniture coverings intact to avoid loose foam, and vacuum with a HEPA filter to remove small particles. Use caution removing carpet, as padding may contain PBDEs. Learn more.
How are we exposed to it? Toluene is a solvent used in household products including paint, glue and additives to gasoline. It is sometimes abused by sniffing or “huffing”; other high exposures come from a workplace setting.
Health effects: Developmental problems with speech and motor function referenced in the Lancet article are associated with women sniffing glue or huffing paint during pregnancy, and from workplace exposures. Toluene in high doses is linked with potential nervous system, kidney or liver problems.
Tips for dealing with it: Commonsense ways to reduce exposures to this and other organic solvents at home include taking care around anything with fumes (gasoline, paint thinner, fingernail polish remover, etc.). When you work with these chemicals, do so in a well-ventilated area. Learn more.
Also known as: Tetrachloroethylene, perchloroethylene, PCE
How are we exposed to it? Dry cleaning is the No. 1 use of PERC, and it may be especially worrisome for those who work in dry cleaning. It may also be found in water and in some household products, such as spot removers.
Health effects: In one recent study, prenatal exposure to PERC was associated with lower scores on some cognitive tests. According to the EPA, this chemical is also associated with liver problems and an increased risk of cancer.
Tips for dealing with it: Learning about PERC is crucial if you work for a dry cleaner, but people may also be exposed at low levels through dry-cleaned clothes. To avoid it, seek “green” dry cleaning companies that don’t use PERC. Learn more.
How are we exposed to it? Burning coal releases mercury into the environment; coal-burning power plants are the largest human-caused source of mercury emissions in U.S. air. Burning hazardous waste, producing chlorine and improper disposal can also release mercury into the environment. Airborne mercury eventually settles into water or on land. Toxic methylmercury is formed by certain microorganisms when mercury ends up in water, and it can build up in fish and animals that eat fish. Human exposure typically comes from eating fish.
Health effects: Methylmercury is associated with impaired neurological development in young children. Large amounts of mercury can also damage the brain, heart, kidneys, lungs and immune systems of people of all ages. While research shows most people’s fish consumption does not cause a health concern, high levels of methylmercury in the bloodstream of unborn babies and young children can harm developing nervous systems, reducing the ability to think and learn.
Tips for dealing with it: Available information suggests pregnant women and young children need to take particular care when choosing fish. The 2010 Dietary Guidelines for Americans recommends pregnant or breastfeeding women consume 8 to 12 ounces of seafood a week, but avoid king mackerel, shark, swordfish and tilefish. Learn more on mercury content in fish from the FDA or about the safety of fish during pregnancy; more about efforts to limit mercury pollution.
Also known as: Polychlorinated biphenyls
How are we exposed to it? PCBs were banned in the U.S. in 1979. Before that, they were used in a wide range of products including industrial equipment, oil-based paint, caulking and floor finishes. These chemicals take a long time to break down and tend to accumulate in animal fat, so we can be exposed to them through eating fish, meat and dairy products.
Health effects: High levels of PCBs are associated with lower IQ in children. In adults, one recent study found a link between higher levels of PCBs in the elderly and diminished mental abilities. PCBs have been shown to cause cancer in animals, as well as to harm the immune, reproductive, nervous and endocrine systems. Human studies provide supportive evidence for the ill effects of PCBs.
Tips for dealing with them: Again, the single most practical step you can take may be to carefully watch fish consumption, including checking local fish advisories. Some well-publicized studies around 2003 found high PCB levels in farmed salmon, but that may be out of date; less has been written about the issue since then. Learn more.
Also known as: Dichloro-diphenyl-trichloroethane
How are we exposed to it? Although this chemical pesticide was banned by the EPA in 1972, it takes a long time to break down and tends to accumulate in fat. While DDT levels are declining, we’re still exposed to low levels of it in meat and dairy products. As other parts of the world continue to use DDT in agricultural practices, an effect the EPA calls “atmospheric deposition” has become the current source of new DDT contamination in the Great Lakes.
Health effects: One recent study found that higher levels of DDT (or DDE, which is what the pesticide breaks down into) during the third trimester of pregnancy were associated with lower scores on cognitive tests later in childhood. A 2014 study from Rutgers also found that DDE levels were higher in a group of Alzheimer’s disease patients than in people without the disease. DDT is listed by the EPA as a probable carcinogen that damages the liver, temporarily damages the nervous system, reduces reproductive success and causes liver cancer.
Tips for dealing with it: Some groups that work on this issue suggest eating less animal fat. Perhaps the easiest advice to follow is to avoid eating fish from highly polluted sites. Check state advisories for information: A good place to start is the website of your state parks and wildlife department. You might also avoid eating imported food that may have been exposed to DDT—instead, opt for locally grown food. Learn more.
How are we exposed to it? This is a pesticide that was previously used indoors for killing termites and other insects, but the EPA stopped virtually all residential use of the pesticide beginning in 2000. It’s still commonly used in agriculture, and people are exposed to it in low levels as pesticide residues on food, or because they live or work in agricultural areas where it’s sprayed.
Health effects: Although the EPA says dietary exposure and drinking water estimates make acute and chronic exposure levels not of concern, in a study of 265 children measuring prenatal chlorpyrifos exposure and 7-year neurodevelopment, higher levels of prenatal exposures to this pesticide were associated with issues with memory and intelligence. In adults, high levels overstimulate the nervous system, causing nausea, dizziness and confusion.
Tips for dealing with it: You can avoid low levels on food by choosing organic produce and other products. Learn more.
The following three chemicals are monitored and not allowed to exceed
recommended amounts in municipal water supplies. However, excessive levels can be found in private wells or water systems. If you have a well, it’s a good idea to test it regularly for excess fluoride, manganese and arsenic.
We get low levels of fluoride from toothpaste and from our drinking water. Fluoride is often naturally present in water, but most cities choose to add it to the water in small amounts as it’s considered beneficial for preventing tooth decay. Health problems have been associated with high levels of naturally occurring fluoride in ground water. The Lancet article offers a meta-review of 27 studies and concludes that “children in high-fluoride areas had significantly lower IQ scores than those who lived in low-fluoride areas.” Many of these studies dealt specifically with parts of China with naturally high levels of fluoride in the water. Excessive amounts of fluoride are also associated with higher risk of bone fractures throughout life and cosmetic damage to teeth in children.
It’s a good idea to follow the Centers for Disease Control and Prevention’s recommendations on toothpaste for children: Don’t give toothpaste with fluoride
to kids younger than 2, and supervise kids younger than 6 to be sure they spit out toothpaste. You can find fluoride-free toothpastes from Tom’s of Maine, Auromére, TheraNeem and J¯ASÖN, among other brands. Learn more.
Like fluoride, manganese can be tricky because in low doses it’s fine—in fact, manganese is an essential nutrient. However, at high doses it becomes problematic. Most problems with manganese come from occupational exposures of adults, as it’s related to mining, welding and manufacturing steel. In high doses, manganese in drinking water has been linked to hyperactivity and behavior problems in schoolchildren, as well as reduced school performance. Adults exposed to high levels occupationally have developed symptoms resembling Parkinson’s disease. Learn more.
Another substance found in water naturally or because of pollution, arsenic has industrial applications, and people may be exposed to it on the job. It has been linked to cognitive issues in children, including in a recent study in Maine, where arsenic-contaminated water was found in local wells. Other related effects include skin damage or problems with circulatory systems, and it may increase the risk of cancer. Learn more.
Where Do We Go from Here?
It’s alarming to think these chemicals may affect children’s mental development, yet there’s no guarantee this is a complete list. Although many of these chemicals have been phased out, we continue to live with the residues, including lead paint in our homes and PCBs in our food supply. Wouldn’t it be better to improve regulations and keep dangerous substances from becoming widespread in the first place? Passed in 1976 and not updated since, the Toxic Substances Control Act (TSCA) is so weak that the EPA has only been able to require testing on less than 2 percent of the more than 80,000 chemicals that have been on the market at some point since the TSCA was adopted. Protecting our collective neurodevelopment is just one more reason to update these regulatory standards.
How to Help
Learn more about the quest to rid toxic chemicals from our environment.
Environmental Working Group
Natural Resources Defense Council
Safer Chemicals, Healthy Families
Megan E. Phelps is a freelance writer based in Lawrence, Kansas. Other environmental articles she has written for Mother Earth Living include Obesogens: The Hidden Culprit of Weight Gain and Reduce Cancer Risk: Eliminate Chemical Carcinogens from Your Home.