A chemical-free world is not possible. Everything on Earth — people, plants, animals, cars, rocks, air — is made up chemicals, and everywhere we go, chemicals are all around us. But while some chemicals, like oxygen and hydrogen, are essential components for maintaining life, others pose a significant threat to human health.
Some environmental chemicals (which are often, but not always, man-made) have been linked to physical and cognitive health conditions and even DNA change. Many of these chemicals, such as arsenic, phthalates, polyfluoroalkyl and volatile organic compounds, to name a few, are found in a range of common household or industry products that we use or are exposed to on a regular basis, including cleaning supplies, car exhaust and certain kinds of cosmetics.
Because of the ubiquity of chemicals in our environment, humans are exposed to hundreds of different chemicals and compounds through a variety of pathways each and every day. Whether it’s the food we eat, the air we breathe, or the products we keep around the house, chemicals from our environment are constantly entering our bodies through our skin, our digestive systems, and our lungs.
This can make it difficult to determine how (and how much of) certain chemicals are entering our bodies; in most cases, there is not one single source for any given chemical that may be found in our bodies. For this reason, it can also be challenging to link exposure to a specific chemical with health effects that may occur years later.
How do scientists study exposure to environmental chemicals and health?
To overcome these challenges, scientists have developed laboratory and computer-based methods to estimate total exposures and risks from chemicals encountered in our daily lives. Included among these methods are a variety of biomonitoring tools, predictive models, and databases that are used to gather, store, and analyze chemical data and to understand how humans are exposed to chemicals and what the long-term implications are. For example, the Environmental Protection Agency’s Stochastic Human Exposure and Dose Simulation Model (SHEDS) can estimate the range of total chemical exposures in a population from different exposure pathways (inhalation, skin contact, dietary and non-dietary ingestion) over different time periods, given a set of demographic characteristics.
One of the prime sources for data on exposure to environmental chemicals and human health comes from the National Health and Nutrition Examination Surveys (NHANES). This is a program of epidemiological studies run by the US Centers for Disease Control and Prevention. NHANES monitors the health status of adults and children in the US with a representative sample, using both interviews and data from biological measurements and physical examinations.
Some of the information collected includes urine and blood samples, which can be used to track exposure to environmental chemicals. This provides a picture of the emerging risk hazards from chemicals – scientists can test the volume of a given chemical in urine or blood and see what the associations are with a range of health conditions. Researchers have been doing this since the 1980s, and scores of studies have been released detailing the associations between concentrations of environmental chemicals in the body and different health outcomes.
Effects on physical health
The association between exposure to these kinds of chemicals and human health has been well documented in research using data from NHANES. While many environmental chemicals have been studied, I’ll focus on a few chemicals that are fairly well-known.
Looking at NHANES data from 2009-2010, researchers found an association between high blood pressure in adults and higher concentrations of heavy metals, arsenic and phthalates in urine. Other research has also associated higher urinary arsenic concentrations that could be found in contaminated groundwater or in foods (eg, grains) with impaired kidney function and gout disease.
Bisphenol-A and triclosan, used in consumer products including soaps, detergents, toys and surgical cleaning treatments, among other things, have been found to affect immune function and the age at which menstruation starts. Studies have also linked these chemicals to breast cancer, early menopause, miscarriage, infertility, and a host of other reproductive problems.
Phthalates, a chemical that makes plastic and vinyl more flexible, are found in a variety of everyday products including plastic bottles, pharmaceutical pills, cosmetics, food packaging, and many household cleaners and detergents. These chemicals have been shown to play a role in increased body mass index, diabetes, worse insulin resistance, higher allergy and asthma rates and decreased testosterone in both adults and children. Prenatal exposure to phthalates is also linked with adverse birth outcomes. And while research is ongoing, phthalates are listed as “reasonably anticipated to be a human carcinogen” in the Thirteenth Report on Carcinogens published by the National Toxicology Program.
Environmental chemicals may be associated with oral health problems as well. In one recent study, researchers found that people with gum disease, bone loss around the mouth, and tooth loss not due to injury were found to have higher levels of heavy metals, phthalates, phenols, parabens and pesticides (among other chemicals) in their urine. Such harmful exposure could cause defects in the development of tooth enamel.
Environmental chemicals in the brain
Environmental chemicals can also adversely influence brain development, particularly in children and older adults.
For example, frequent use of household products with higher levels of pyrethroid insecticides and polyfluoroalkyl chemicals are linked to learning problems and impaired attention in children. In one recent study, researchers found that women who live in close proximity to pesticide sites during pregnancy are two thirds more likely to have children with autism or other developmental delays than women who live far away from such sites.
Other recent research suggests that BPA exposure may also contribute to autism risk, while past studies have shown that children with autism are more likely to have been exposed to air pollutants in early life and during fetal development than those without the condition. A similar link has been observed for schizophrenia, as well.
Of particular concern is exposure to PAHs (polycyclic aromatic hydrocarbons) during pregnancy, as some of these chemicals can cross the placental barrier and affect fetal neurodevelopment. In a study published in May, researchers found that children who were exposed to PAHs during prenatal development scored significantly lower on IQ tests at age 5 than children without exposure to the pollutants. These effects were particularly strong among poorer children, possibly because of stress-induced brain changes that increase vulnerability to chemical exposures.
Additionally, the American College of Obstetricians and Gynecologists lists prenatal exposure to phthalates as a risk factor for impaired neurodevelopment in girls.
In the elderly, vision, hearing and balance can be altered through chronic exposure to a range of chemicals including heavy metals, phthalates, arsenic, pesticides, phenols, hydrocarbons and polyfluorinated compounds. And it has been further observed that these chemicals might lead to difficulties in thinking and memory as well. It is thought that these chemicals may disrupt nerve regulation in the brain.
Effects on emotions
If environmental chemicals can impair our organs and change our nervous system, then it only makes sense that they might have effects on our emotional health, as well.
Indeed, researchers recently discovered that higher levels of parabens and polyaromatic hydrocarbons in urine may be an indicator that a person needs more emotional support, such as talking over problems or help making difficult decisions, than others with lower concentrations do. Such relationship exists whether or not people might have other health conditions, including mental health problems.
These chemicals are both quite common. Parabens are often used as preservatives in cosmetic and pharmaceutical products, and polyaromatic hydrocarbons are found in exhaust, asphalt, coal tar, smoke, soil and charbroiled foods.
These chemicals may trigger a physical reaction that ultimately leads to the disruption of emotions. Daily exposure to these chemicals could lead to a person developing a dependency on them. This can induce inflammation or immune function to alert cell injury or damage. And that could, in turn, chronically disturb neuron functioning, leading to the disruption of emotions, and hence a need for more emotional support. Recent research has even linked these pollution-induced brain changes with heightened suicide risk.
How do we know when we are exposed to unnecessary environmental chemicals?
Once we know the relationships of harmful chemicals and health, we can start to figure out how to lessen or prevent exposure to these chemicals. This could mean reducing our use of the consumer products that contain these substances. However, consumers should be discerning when choosing replacement products, as scientists recently discovered that toxic chemicals are present even in products labeled as “non-toxic,” “all-natural,” “green” or “organic.”
Buildings built more than 30 years ago could be another source of exposure and therefore need our attention to renovate. They could emit chemicals that harm our health because they have building materials that contain harmful chemicals like lead, as well as other environmental pollutants like mold.
A screening program is one of the ways to identify housing and chemical issues at an early stage.
Another way is through an unpleasant smell which is exactly what it sounds like. The presence of unpleasant odors might direct us to where the excess chemicals around us are. These issues could also be detected by reviewing self-rated health. This is an indicator of physical and mental health issues, created by asking people questions about their health. And based on new research about environmental chemicals and oral health, one could also look at teeth from time to time.
Additionally, personalized tools like the EPA’s MyEnvironment site can help individuals identify the most common hazardous chemicals they come across in their everyday lives. The EPA tool allows a user to enter geographic information (zip code, city or state) and find federal, state and local information about environmental conditions and features in that area, linking the toxin(s) with potential health effects.
These types of preventative measures could be carried out on a regular basis for individuals and each household to suggest when to examine and remove the unnecessary environmental chemicals in order to improve and sustain our health, well-being and quality of life.