Do Environmental Toxins Cause Brain Damage in Children?
There will be approximately 11,850 births today in the U.S. and Canada, and each of those precious little bundles will already carry with them the DNA blueprint for future development along with some very unwelcome party crashers: more than 200 industrial chemicals, pesticides, and other pollutants which will make it harder, or even impossible, for a child to fulfill their genetic potential.
In body burden studies performed by the Environmental Working Group and their partner, Commonweal, an average of 287 chemicals, including perfluorochemicals, brominated flame retardants, pesticides, and heavy metals, were found in newborn cord blood. Of these chemicals, 180 are linked to cancer in humans or animals, 208 are known to cause birth defects or abnormal development according to animal tests, and 217 are known to cause damage to the brain or nervous system. These findings are especially shocking when you consider that newborns, like fetuses, are virtually incapable of expelling toxins since their detoxification organs (like the liver and kidneys) haven’t fully developed. Further, infants’ blood-brain barrier has not yet formed to protect their rapidly developing brains from the harm of these chemicals.
Body, mind, and environmental toxins
While a list of chemicals found in the blood of our children is certainly compelling, it doesn’t begin to tell the whole story. What parents really want to know is how those chemicals impact their children post-utero and throughout their lives. This is where the study of children’s environmental health led by a few brave scientists and doctors (battling lack of funding, chemical company agendas, and a general disinterest in public health) come in to champion awareness that hopefully leads to change.
The brain of the matter
The study of children’s environmental health is a relatively new field of medicine with just over a handful of scientists pursuing it full time in the U.S. and Canada. One of the leaders in the field is Bruce Lanphear, MD, MPH, a founding member of the International Society of Children’s Health and the Environment (ISCHE). According to him, we just aren’t focusing enough on our children’s brains.
According to research done by Dr. Lanphear, there’s a typical ingredient list of neurotoxic chemicals brewing in a large percentage of North American children.
- Lead: 89%
- Mercury: 100%
- PCBs: 100% (despite being banned in the 1970s)
- OP pesticides: 80%
- BPA: 96%
- Flame retardants: 100%
Triclosan (TCS), an antibacterial pesticide and endocrine-disruptor, was found in 87% of pregnant women and studies have noted an increased level of testosterone in the cord blood of infants with TCS exposure.The brain is particularly vulnerable to the effects of toxin exposure, says Lanphear, and this is especially true during the foundational years of childhood. While it continues to grow into adulthood, the first eight years of development are a time where toxin exposure can have the most profound effects.
“[The brain] makes us who we are.” says Lanphear. It’s so important, in fact, that it has its own built-in biological armour: the blood-brain barrier. Like the placenta, the blood-brain barrier is really more like a porous protection system that helps keep unwelcome guests out. But the blood-brain barrier isn’t fully developed at birth and doesn’t function optimally under stressful conditions like high blood pressure, infection, and inflammation, or when exposed to high concentrations of chemicals in the blood, microwaves, and radiation.
Additionally, different toxins will have different effects on the brain depending on the stage of development, the type of toxin, and the length and degree of exposure. For instance, the hippocampus grows more during fetal development, while the frontal cortex is more vulnerable during early childhood. Mercury can cause cell death, while lead disrupts neurotransmission. DDT, PCB, PBDEs, phthalates, and BPA disrupt estrogenic or thyroid hormones, and many airborne pollutants, arsenic, lead, and BPA seem to cause epigenetic changes, affecting the way the genes are expressed.
Thinking beyond cancer
Despite the adverse impact on other systems of the body, governmental regulations are focused on the use of carcinogens—the toxins that cause cancer—and not on those that affect hormonal systems or the brain. Thanks in large part to Rachel Carson’s groundbreaking book Silent Spring, which brought to light the link between the use of synthetic pesticides and increased cancer rates and brought about the 1969 ban on DDT, the EPA now has two classes of chemicals: those linked to cancer and everything else.
For chemicals linked to cancer, there is no identified safe level of exposure. However, for non-carcinogenic toxins, such as those linked to hormonal effects or brain damage, risk is assessed based on exposure. The assumption is that only after a certain level of exposure would the toxin become problematic to humans, a practice that now seems out of step with the reality of harm.
Lanphear reminds us that “Not all chemicals are bad.” Yet, it only takes a tiny dose of the bad chemicals to “have a lifelong impact on children.” The amounts seen in children today are correlated with serious effects, including diminished intellectual ability. “Children with more exposure to toxins won’t reach the same cognitive abilities as those exposed to less,” says Lanphear. He goes on to say, “Up until recently, we thought that 70 percent of ADHD, Aspergers, autism were due to genetics…The truth is that it’s 100 percent environment and 100 percent genetic: it’s the interplay of both.”
Note from the editors
We recognize that the construct of “Intelligence Quotient” (IQ) as a tool of measuring intellect has been substantially misguided over the years with inherent biases that disfavor people of colour and those of lower socio-economic status and “non-standard” culture. However there is important evidence that toxins can negatively impact intellect and overall cognitive development that is well-worth noting. We therefore encourage readers to keep in mind that IQ—as fraught as it is—is still one of the few means of standardized assessment available with which to measure and provide data about the impact of toxins on the brain.
The key to prevention is to identify the environmental risk factor—which, remember, also influences genetics—and remove it. And there have been some successes in this regard. The Lead-Crime hypothesis proposes that there is a link between the generation of people exposed to leaded products, especially gasoline, and increased aggression. Since lead has been removed from gasoline, paints, and children’s products, countries that have prohibited the sale and use of leaded gasoline have had a corresponding decrease in violence. As chemicals such as DDT, PBDEs and PCBs are phased out of use, so do their levels diminish in our babies.
Common neurotoxins to know
Industrial chemicals have made their way into nearly every aspect of modern life, from cosmetics and shampoo to clothing and sheets. Understanding the names, their danger, and where to find them arms you with knowledge to buy better. Here’s what you need to know about some of the most common toxins that are the most important to avoid, especially during pregnancy and throughout the early years of your child’s development.
Arsenic, lead, and mercury are three of the most common, persistent, and highly toxic heavy metals. As these can bioaccumulate (be stored) in our bodies, there are no safe levels. The research suggests that most (and perhaps all), heavy metals pass through the placental barrier and can permanently damage organs and brain development. Arsenic has been found at about 80 percent concentration in baby’s cord blood and studies have found double the concentration levels of mercury in baby’s cord blood compared to their mother.
The inorganic version of arsenic which enters the environment via treated lumber, coal-fired power plants, and arsenical pesticide runoff, is a known carcinogen. Arsenic’s ubiquity in conventional rice makes it the highest food source of arsenic exposure for humans, especially babies. Relative to body weight, babies consume three times more rice than adults, primarily in the form of infant rice cereal. Recent testing by the FDA shows that pregnant mothers who eat more rice may have children with decreased learning performance.
Exposure to lead has been linked with hyperactivity, lower IQs, and neurocognitive disorders such as ADHD; can damage kidneys, blood, muscles, and bones; and is likely carcinogenic. While lead is still found in 100 percent of babies born today, our exposure has decreased thanks to environmental regulations on coal burning, emissions, and the use of lead in consumer products such as paint and gasoline.
A particular risk to babies-to-be and children. Like with many heavy metals, small amounts of mercury occur naturally in the environment, but there is no known safe level for humans. It poses a risk to a child’s developing brain, neurological system, and organs, and any amount can cause permanent damage. The “good news” is that the highest exposures to mercury come from activities such as coal-burning power plants, the healthcare sector, mining, and charcoal production. Because these sources are man-made, they can be regulated and improved. The greatest source of mercury exposure for most children is from fish, but they can also be exposed from rice and from medical products, such as the flu vaccine and amalgam fillings.
Note from the editors
Vaccines are always a hotly debated topic and we at EcoParent strive to create awareness, inspire critical thinking, and encourage readers to educate themselves. With regards to the presence of mercury in flu vaccines: Historically, thimerosal (an ethylmercury) was used as a preserving agent in multi-dose vials of vaccination fluid. And although believed to be safe in low doses, it was removed from the ingredient list in order to protect infants and children from public concerns about mercury exposure. Currently in Canada and the U.S., there is no mercury in single-dose flu shot or other common childhood vaccinations, although it is still used in multi-dose flu vaccine vials.
Persistent organic pollutants (POPs)
POPs are toxic chemicals found in pesticides, non-stick cookware, and flame-retardants that travel on wind and water and accumulate in the bodies of animals. Thanks to epigenetics (when environmental factors influence gene expression) they may very well find their way into your future grandchildren because they are readily passed across the placenta and are difficult to eliminate from the body. POPs travel easily and widely and many accumulate in remote, seemingly pristine places like the Arctic, where they get stuck because of wind patterns and the cold.
Small amounts can cause brain changes that can manifest in learning disabilities, ADHD, autism, and in thyroid problems, hormonal disruption, and cancer. Canada, the US, and more than 90 other countries regulate the twelve most dangerous POPs—including furans and dioxins—as part of the 2014 Stockholm Convention. Since POPs such as DDT and PCBs were targeted under the original 1972 agreement, they have been substantially reduced in the environment, and consequently in humans (although many of them, such as PCBs, are still found in nearly 100% of newborns). Though there are twelve POPs targeted under the 2014 agreement, many additional POPs are still out there with new ones being created.
PBDEs and Tris
These are chemical flame retardants that were commonly used for children’s sleepwear and mattresses. Brominated flame retardants (PBDEs) and phosphate esthers (Tris), including TDCP and TCEP phosphate, have been linked to neurological disorders, hormonal disruption, organ damage, thyroid disorders, and fertility problems, and may be linked to cancer.
Young children are still one of the groups most highly exposed to Tris flame retardants even though it was banned in 1977 from children’s sleepwear when it was discovered to mutate their DNA. PBDE levels are 75 times higher in American women than their European counterparts, likely because of a California law requiring flame retardancy for items sold in that state. Both the United States and Health Canada have asked manufacturers to phase out certain PBDE compounds, but PBDE and Tris are still common in children’s products. As well, many of the new chemical flame retardants on the market to replace them are thought to be just as bad but as they have been subjected to less robust testing, their effects are even less clear.
Perfluorinated Compounds (PFCs)
PFCs are used in stain guards to magically keep red wine from staining your white couch, make cookware nonstick, and make clothing waterproof. They are also used in grease-resistant food packaging such as hamburger wrappers, chip bags, and microwave popcorn packages and can even coat your dental floss. PFCs have been linked to cancer and birth defects and two of the most infamous—PFOA and PFOS—have been found in nearly every human studied, with levels in children often higher than in adults. Because of the known health concerns, these are mostly being phased out in the United States and Canada, but it’s still worthwhile to know what’s in the products you purchase.
An unintended by-product of many industrial processes involving chlorine including the manufacturing of pesticides, the production and incineration of PVC plastics, and paper bleaching. Polychlorinated biphenyls (PCBs) are dioxin-like compounds that, unlike most dioxins, are intentionally produced for use in electrical insulators, fire-fighting compounds, paint, lubricants, and transformer fluid. The IARC (International Agency for Research on Cancer) considers the most potent dioxins to be Group 1 carcinogens (definitely cancer-causing). They are linked to birth defects, infertility, reduced sperm counts, endometriosis, diabetes, learning disabilities, immune system suppression, lung problems, skin disorders, and numerous cancers. Traces of dioxins can be found in air, water, soil, and—from there—they work their way up the food chain and into the fat of fish, animals, and humans. Diet, particularly through consumption of meat and dairy, is considered our primary source of exposure.
These make up the majority of the POPS restricted under the Stockholm Convention. Nevertheless, pesticides such as DDT continue to be freely used in much of the developing world despite the known disastrous effects on human health. Many newer pesticides, like glyphosate (found in Round-Up) claim to be less devastating but are just as pervasive. And in the case of glyphosate, research is now showing that it can be linked to miscarriage, reproductive damage, and ADHD, and animal studies show that it has the ability to alter genes.
Volatile organic compounds (VOCs)
VOCs include a wide-range of carbon-based chemicals that easily vaporize (off-gas) from numerous household and workplace sources. They can cause immediate health issues, like headaches, and numerous VOCs are linked to neurological and organ damage, chemical sensitivities, and cancer. Pregnant women are especially vulnerable, as studies have suggested that increased exposure is directly linked to miscarriage and lower neurological function and congenital malformation in offspring. They are especially likely to be present in the nursery because often the products that furnish the baby's room are new and chemical-laden.
VOCs include formaldehyde, phthalates, gasoline, benzene, and solvents including toluene, xylene, styrene, and perchloroethylene (PERC), used in dry-cleaning. Many VOCs, such as those found in cosmetic products, furniture, paints, and cleaning items, have an odour and the “sniff test” can alert you to their presence. VOCs off-gas and concentrations will usually decrease over time, so it’s strongly advised to air-out rooms and objects where these have been used before spending time in or near them.
A smelly, colourless, flammable VOC classified as a Group 1 carcinogen by the IARC. It can also irritate the eyes, nose, and throat, and trigger asthma. Formaldehyde can be found in furniture and toys and items made with pressed wood or particle board. It can also be found in some glues, such as those used in hanging wallpaper or laying carpet, and it is a byproduct released from as much as one-third of beauty products, like shampoos—even those marketed to children. Emissions from furniture generally decrease over time but it can take seven years just to reach minimal levels.
Plasticizers found primarily in cosmetics and plastics. They are considered likely hormone-mimickers and have been linked to preterm birth, infertility, and cancer. A CDC study found 75 percent of participants had detectible levels of phthalates in their bodies. The six phthalates considered most hazardous have been banned in the EU since 1999. The United States and Canada have also banned some of phthalates in some children’s products and toys, but not in personal care products.
BTEX: Benzene, toluene, ethylbenzene, and xylene
BTEX can be found all together or individually and can contaminate air, soil, and water. They range from known (benzene) to suspected human carcinogens. They can pass through breastmilk and the placenta, and have been discovered to accumulate in women’s breast tissue. They are routinely found in petroleum byproducts and all or some can be found in solvents, paints, nail polish and hair dyes, some cleaning products, and cosmetics.
Plastics are everywhere. They can do amazing things, but unfortunately many come with big health costs, including exposing us to chemicals that mimic estrogen. Some of the worst offenders are in products that we find commonly in our homes.
Also known as vinyl, PVC contains lead, phthalates, and releases dioxin. It is linked to neurotoxic effects and endocrine problems. It is found in soft, pliable plastic products like crib mattress covers, shower curtains, and in vinyl blinds and siding.
BPA, BPS, and 38 other known or suspected endocrine disruptors contain bisphenol. BPA may cause problems with brain and hormone development, decreased sperm counts, erectile dysfunction, heart disease, diabetes, liver abnormalities, and breast cancer. BPS can disrupt a cell’s normal functioning and could lead to diabetes and obesity, asthma, birth defects, and cancer. Bisphenol-containing compounds, especially BPA, can be found in hard plastic items including baby bottles, and in the lining of canned goods, such as baby formula—even in ones labelled “BPA-free”!
A chemical byproduct of industrial processes that is added to some plastics (and some foods! Its nitrogen content artificially inflates apparent protein content and it has been discovered by Chinese officials in dairy products processed there). Melamine products may also release formaldehyde and is found in many child-friendly containers and cups that are sold as “BPA-free” or “shatterproof.” It is linked to kidney failure.
Also called styrofoam, this contains the toxic substances styrene and benzene, suspected carcinogens and neurotoxins that are hazardous to humans. Hot foods and liquids, alcohol, oils, acidic foods, and red wine all cause polystyrene to release toxins into the food or drink its housing.
A final note about fluoride research
In many ways, the above-mentioned chemicals are the easy ones to avoid because they’ve been identified as hazardous, and in many cases have been replaced with better options. The more difficult chemicals to rid ourselves of, says Lanphear, are the ones that we have ingrained into our public health strategies but without ample proof that they are safe or effective. As an example he points to fluoride used in water.
Fluoride is a chemical added to much of the water supply in both the U.S. and Canada in an attempt to prevent tooth decay. Lanphear says that from his perspective as a public health scientist, the research on fluoride’s safety and efficacy was never sufficient. Officials allowed it relying primarily on observational studies that showed topical fluoride’s small benefit in reducing cavities. The same benefit was never demonstrated for ingested fluoride, nor has it ever been proven to be an essential nutrient required for proper body functioning. Lanphear points out that there is evidence to show that it may actually interfere with healthy body functioning, especially in combination with toxins like aluminum and lead.
Fluoride accumulates in the body, particularly in the bones and pineal gland, and the amount in bones increases over a lifetime, with children taking more into their bones than adults. One study has correlated greater exposure with reduced intellectual function. Fluoride also crosses the placenta and is linked with delaying the appearance of teeth, which increases the risk of decay. It is also associated with dental fluorosis (tooth discolouration), now estimated to affect 41 percent of American children.
Amidst all the bad news in the toxic contamination affecting our children is this silver lining: when we decide to take action on a chemical, we have the power to make a difference. We banned lead in gasoline and paint in North America and not only did the corresponding levels in our children’s blood streams fall, but so did crime rates in urban centres most affected by lead poisoning. When we ban the known neurotoxins, the changes are notable in our bodies. We can make a difference: “If you want to bring about change in how we regulate chemicals,” says Lanphear, “talk with moms and pregnant women.” So he talks. I write. And parents are left to lead the charge for change and hope.
For further reading visit Fall 2019 Extras.