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Depressing because the 4 chemicals (benzene, toluene, ethylbenzen, xylene) are so pervasive in indoor air. And now to find that at levels considered "safe" by the EPA there may be disruption of our hormones (endocrine systems). Of course they are already known to have health effects on the human body other than what is discussed in this study. For example, toluene has a number of central nervous system effects. The EPA says toluene , which is found in highest concentrations in indoor air from the use of common household products (paints, paint thinners, adhesives, synthetic fragrances, and nail polish). Outside - the biggest source of toluene is from automobile emissions. Some ways to lower exposure to these 4 chemicals: read product labels and when using a product that says to use with proper ventilation - open the windows and let the room ventilate!  Don't smoke. (For example: the EPA says tobacco smoke contains benzene and accounts for nearly half the national exposure to benzene) The study researchers themselves said the EPA should be paying more attention to these air contaminants. I read this at Scientific American, but it came from EHN:

Scientists warn of hormone impacts from benzene, xylene, other common solvents.

Four chemicals present both inside and outside homes might disrupt our endocrine systems at levels considered safe by the U.S. Environmental Protection Agency, according to an analysis released today.

The chemicals – benzene, toluene, ethylbenzene and xylene – are ubiquitous: in the air outside and in many products inside homes and businesses. They have been linked to reproductive, respiratory and heart problems, as well as smaller babies. Now researchers from The Endocrine Disruption Exchange (TEDX) and the University of Colorado, Boulder, say that such health impacts may be due to the chemicals’ ability to interfere with people’s hormones at low exposure levels“There’s evidence of connection between the low level, everyday exposures and things like asthma, reduced fetal growth,” said Ashley Bolden, a research associate at TEDX and lead author of the study. “And for a lot of the health effects found, we think it’s disrupted endocrine-signaling pathways involved in these outcomes.”

Bolden and colleagues – including scientist, activist, author and TEDX founder Theo Colborn who passed away last December – pored over more than 40 studies on the health impacts of low exposure to the chemicals.They looked at exposures lower than the U.S. Environmental Protection Agency’s reference concentrations for the chemicals, which is the agency’s estimated inhalation exposure level that is not likely to cause health impacts during a person’s lifetime.

Many of the health problems – asthma, low birth weights, cardiovascular, disease, preterm births, abnormal sperm – can be rooted in early disruptions to the developing endocrine system, Bolden said. The analysis doesn’t prove that exposure to low levels of the chemicals disrupt hormones. However, any potential problems with developing hormone systems are cause for concern.

“Hormones are how the body communicates with itself to get work done. Interrupt that, you can expect all sorts of negative health outcomes,” said Susan Nagel an associate professor at the University of Missouri-Columbia Obstetrics, Gynecology and Women's Health School of Medicine who was not involved in the study.

The four chemicals are retrieved from the wellheads during crude oil and natural gas extraction and, after refining, are used as gasoline additives and in a wide variety of consumer products such as adhesives, detergents, degreasers, dyes, pesticides, polishes and solvents. Ethylbenzene is one of the top ten chemicals used in children’s products such as toys and playground equipment, according to a 2013 EPA report. Toluene is in the top ten chemicals used in consumer products such as fuels and paints, the report found. 

All four get into indoor and outdoor air via fossil fuel burning, vehicle emissions and by volatizing from products. Bolden said studies that measure the air in and around homes and businesses find the chemicals 90 to 95 percent of the time. In several of the monitoring studies Bolden and colleagues examined, levels of the chemicals were higher in indoor air than in outdoor air, suggesting that people might be exposed within their homes. “A lot of time indoor air is poorly circulated,” Bolden said.

Benzene, toluene, ethylbenzen, and xylene are added to gasoline and emitted to the air during combustion. (Image: joiseyshowaa/flickr)

Children's brain development being harmed by chemicals in the environment - both before birth and in childhood -  is such an important topic that here are excerpts from two articles about the same report that was just released (in Lancet Neurology).  From Time:

Children Exposed to More Brain-Harming Chemicals Than Ever Before

In recent years, the prevalence of developmental disorders such as autism, attention deficit/hyperactivity disorder (ADHD) and dyslexia  have soared. While greater awareness and more sophisticated diagnoses are partly responsible for the rise, researchers say the changing environment in which youngsters grow up may also be playing a role.

In 2006, scientists from the Harvard School of Public Health and the Icahn School of Medicine at Mount Sinai identified five industrial chemicals responsible for causing harm to the brain — lead, methylmercury, polychlorinated biphenyls (found in electric transformers, motors and capacitors), arsenic (found in soil and water as well as in wood preservatives and pesticides) and toluene (used in processing gasoline as well as in paint thinner, fingernail polish and leather tanning). Exposure to these neurotoxins was associated with changes in neuron development in the fetus as well as among infants, and with lower school performance, delinquent behavior, neurological abnormalities and reduced IQ in school-age children.

Now the same researchers have reviewed the literature and found six additional industrial chemicals that can hamper normal brain development. These are manganese, fluoride, chlorpyrifos, dichlorodiphenyltrichloroethane, tetrachloroethylene and polybrominated diphenyl ethers. Manganese, they say, is found in drinking water and can contribute to lower math scores and heightened hyperactivity, while exposure to high levels of fluoride from drinking water can contribute to a seven-point drop in IQ on average. The remaining chemicals, which are found in solvents and pesticides, have been linked to deficits in social development and increased aggressive behaviors.

But they say the growing body of research that is finding links between higher levels of these chemicals in expectant mothers’ blood and urine and brain disorders in their children should raise alarms about how damaging these chemicals can be. The developing brain in particular, they say, is vulnerable to the effects of these chemicals, and in many cases, the changes they trigger are permanent. The consequence of such brain damage is impaired [central nervous system] function that lasts a lifetime and might result in reduced intelligence, as expressed in terms of lost IQ points, or disruption in behavior,” they write in their report, which was published in the journal Lancet Neurology.

Same report, from Science Daily: Growing number of chemicals linked with brain disorders in children

"The greatest concern is the large numbers of children who are affected by toxic damage to brain development in the absence of a formal diagnosis. They suffer reduced attention span, delayed development, and poor school performance. Industrial chemicals are now emerging as likely causes," said Philippe Grandjean, adjunct professor of environmental health at HSPH.

The study outlines possible links between these newly recognized neurotoxicants and negative health effects on children, including:  - Manganese is associated with diminished intellectual function and impaired motor skills  - Solvents are linked to hyperactivity and aggressive behavior - Certain types of pesticides may cause cognitive delays.

Grandjean and co-author Philip Landrigan, Dean for Global Health at Mount Sinai, also forecast that many more chemicals than the known dozen or so identified as neurotoxicants contribute to a "silent pandemic" of neurobehavioral deficits that is eroding intelligence, disrupting behaviors, and damaging societies. But controlling this pandemic is difficult because of a scarcity of data to guide prevention and the huge amount of proof needed for government regulation. "Very few chemicals have been regulated as a result of developmental neurotoxicity," they write.

The authors say it's crucial to control the use of these chemicals to protect children's brain development worldwide. They propose mandatory testing of industrial chemicals and the formation of a new international clearinghouse to evaluate industrial chemicals for potential developmental neurotoxicity.