Top 10 Most Dangerous Environmental Toxins in the U.S.

HomeScience & TechnologyTop 10 Most Dangerous Environmental Toxins in the U.S.
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Exposure to toxins is part of our everyday lives. While such dangerous contaminants as radon and mercury predate industrialization in some areas, modern chemistry has introduced many other harmful toxins into the environment. For many of these substances, there is much debate about what levels are safe in our background environment. There’s also much disagreement as to the cost versus benefit of containing, removing or monitoring these substances. That said, here are the suspected dangers and sources of 10 common toxins, and how you can limit your exposure.

10. Prescription Drugs

Many pharmaceuticals have been found in municipal water sources.

Photo credit: Denis Pepin/

Descriptions & Dangers: Whatever goes down the drain eventually ends up in the public water supply. United States Environmental Protection Agency monitoring has found trace amounts of pharmaceuticals, cosmetics, and even illegal drugs in municipal water supplies. The exact dangers from this threat are uncertain, but studies have shown that even tiny amounts of estrogen released via discarded birth control pills have affected male fish.
Sources: Water
Precautions: It’s tough to say how much of a health concern this is, as some levels detected are negligible. Millions is spent treating the U.S. water supply to assure its safety. Home filtration may help for some contaminants, but even bottled water is no guarantee against this sort of contamination.


9. VOCs

VOCs can be found in many household products, including paints.

Photo credit: Stefano Lunardi/

Descriptions & Dangers: Volatile Organic Compounds have a high vaporizing pressure and hence a low boiling point, causing them to easily evaporate in room temperature conditions. Some household examples are acetone, formaldehyde, and turpentine. VOC exposure can cause respiratory irritation, memory impairment as well as allergic and immune reactions. VOCs are also suspected cancer-causing agents in humans.
Sources: Household VOCs are found in cleaning fluids, carpets, and paints. VOCs are by-products of protective coatings and may contribute to what has been referred to as Sick Building Syndrome.
Precautions: Many types of VOCs, especially the ozone-damaging chlorofluorocarbons (CFCs) have been banned outright. Recognizing public concern about VOCs, many paint and carpet manufacturers have introduced non-VOC products. Proper ventilation of workspaces and buildings is crucial and public areas are now monitored for VOC content.


8. Perchlorate

Perchlorate has been found in drinking water supplies throughout the U.S.

Photo credit: Hsing Wei

Descriptions & Dangers: A salt compound obtained from perchloric acid, perchlorates have applications ranging from use in thyroid medications to rocket fuel. Its chief hazard in the human body is its ability to block iodine uptake, which has been linked to thyroid ailments and can be especially harmful to the unborn fetus.
Sources: Perchlorate has been found in water sources near military bases and chemical plants. Many perchlorates wind up in our environment from their use in fertilizers and explosives, including fireworks. Perchlorates from construction demolition and fertilizers leech into the soil from runoff, and are then incorporated into plants and later concentrated in grazing animals.
Precautions: In early 2011, the EPA announced it would develop a federal standard to regulate perchlorate in drinking water. Home treatment units are available if perchlorate contamination is suspected.


7. Asbestos

Asbestos can still be found in many older buildings.

Photo credit: Aaron Suggs

Descriptions & Dangers: Asbestos is a naturally occurring fibrous silicate material. Asbestos was used for years because of its heat-resistant and insulation properties before its more insidious nature became known. Asbestos inhalation causes malignant lung cancer in the form of mesothelioma.
Sources: Asbestos was used extensively in the U.S. until the EPA banned it in 1989. It can be found in drywall, pipe fittings, automotive brake and clutch parts and even toys and fireplace logs, but is most commonly found in housing and electrical insulation.
Precautions: Use caution in doing home renovations in older homes where asbestos might be present. Asbestos removal in older buildings employs specialized workers.


6. Molds

Mold is a common problem in many homes.

Photo credit: Tim Arbaev/

Descriptions & Dangers: Molds are fungi that are ubiquitous in warm, humid areas. In any home, the question is not if there is mold, but how much is present. Most mold and yeast spores are benign; large amounts can lead to respiratory concerns and reactions, especially among individuals with pre-existing immunodeficiency disorders.
Sources: Mold is opportunistic, growing anywhere there is a food source and abundant moisture. “Mold” may refer to anything from common molds and yeasts that are used in the production of medicine and fermentation of alcohol, to virulent forms such as Stachybotrys chartarum that produce mycotoxins.
Precautions: Keeping levels of moisture and temperature regulated in the home is a good way to restrain mold growth, especially in warm climates. There’s been much publicity in recent years about the benefits of cleaning the HVAC ducts in your home to remove mold, but a commonly overlooked spawning ground for mold is the crawlspace under your home.


5. Phthalates

Phthalates can be found in many household products, including rubber toys.

Photo credit: Tim Lewis NM

Descriptions & Dangers: Phthalates are esters used anywhere flexibility and durability is desired. Some studies suggest that phthalates may be linked to endocrine disruption as well as increased birth defects in newborn males, especially in the form of undescended testes. Phthalate exposure is also suspected in elevated breast cancer rates. However, the U.S. Food and Drug Administration notes that, “It’s not clear what effect, if any, phthalates have on health.”
Sources: In the home, phthalates are present in shower curtains, toys, upholstery, even the dissolvable coatings of medicines. Anywhere soft flexible rubber parts or coatings are used, you’ll find phthalates. Phthalates are also found in certain lotions, cosmetics and shampoos.
Precautions: While it is virtually impossible to completely avoid phthalates in our plasticized society, it is possible to limit exposure, especially when pregnant. Avoid using products that use the word “fragrance” among the ingredients. Get rid of that vinyl shower curtain, and it might be wise to avoid or limit use of type 3 PVC plastics.


4. Pesticides

Pesticides can be harmful in several ways.

Photo credit: Vincent Horn

Descriptions & Dangers: The use of DDT was banned in 1972 after the publication of Silent Spring by Rachael Carson. Another persistent pollutant, DDT still shows up in the blood tests of many Americans decades later and can lead to impaired neurological development, diabetes, and breast cancer.
Sources: DDT was used extensively to eliminate malaria-carrying mosquitoes up until the 1970s. Other pesticides are still used in agriculture and by pest treatment and lawn care services.
Precautions: Obviously, stay off of lawns that have just been treated. Check to see what kind of pesticides your pest treatment service is using. Non-toxic insecticides such as carbamate and organophosphate are now in use, although these have the drawback of being cost prohibitive.


3. PCBs

Although PCBs have been banned for years, they are still present in the environment.
Descriptions & Dangers: Widely used in the U.S. as a coolant fluid for industrial electric equipment, polychlorinated biphenyls are persistent organic pollutants that can cause nervous and endocrine problems in the human body. PCBs have been linked to deadly forms of liver and brain cancer. In the Great Lakes region alone, the EPA estimates that PCBs will be responsible for 38,255 cancers in the next 70 years.
Sources: PCB use was banned in 1976, but an estimated 3.4 billion pounds were produced from 1929 to 1989 worldwide, much of it remaining in the air, water and soil.
Precautions: State warnings are issued against consumption of top feeder fish that accumulate toxins from further down the food chain in PCB-contaminated areas.


2. Radioactivity

The EPA recommends all homes be tested for radon.
Descriptions & Dangers: Natural deposits of radon and uranium can be found in every U.S. state and radon may even be present in the granite countertop in your kitchen. The EPA estimates that around 1 in 15 homes nationwide has elevated radon levels, and the agency cites radon with causing more than 20,000 cancer deaths per year.
Sources: Ironically, a large amount of radioactive by-product gets released from burning coal, far more than was released from the Fukushima or Three Mile Island disasters. In addition to what leeches out naturally through the soil, a few atoms of non-naturally occurring plutonium are now present in each of our bodies, the result of mid-20th century nuclear testing.
Precautions: The EPA recommends that all homes below the third floor be tested for radon. Homes in radon-prone areas are advised to have radon detectors as standard equipment.


1. Heavy Metals

Pregnant women and young children should limit their fish consumption to avoid mercury poisoning.

Photo credit: Joey Rozier

Descriptions & Dangers: As workers cleaning up the World Trade Center site began reporting respiratory and other health issues, one of the first culprits doctors suspected was element 48, or cadmium, used in electronics and one of the most infamous in what is known as the “Poisoner’s Corridor” of the Periodic Table. Toxic elements mimic key nutrients and thus are unwittingly incorporated in areas of the body where they can wreak havoc. Mercury, arsenic, lead, and even some forms of aluminum and nickel are toxic, as is thallium, an Agatha Christie murder favorite. Young children are particularly at risk for heavy metal poisoning.
Sources: The most common sources for these metals have been well documented. Mercury is most often ingested by eating fish, particularly King mackerel, lake trout and swordfish, which bioaccumulate the element. Many older homes still contain lead-based paints. Other common sources of heavy metals include mining and smelting operations. For example, mercury is used to separate gold from ore because of its affinity to the metal. In many poorer nations where there is no environmental oversight, leftover sludge is just allowed to flow back into the water and soil.
Precautions: The EPA recommends that pregnant women, those who are nursing and young children limit their consumption of fish to 12 ounces per week, and avoid King mackerel, shark and swordfish. Other sources recommend pregnant women and young children limit their consumption of tuna, another fish in which mercury bioaccumulates. Also, the federal government has for several years recommended that people replace their old mercury thermometers with newer digital models. Residents who live near historic mining sites should have their home and well water tested for contaminants.


One More: BPA

Another estrogenic source that has been in the news in recent years, bisphenol-A is a known endocrine disruptor. BPAs may still be found in type 3 and 7 plastics, which are being phased out in favor of the more common type 1 and 2 BPA-free plastics.


Written by

David Dickinson is a backyard astronomer, science educator and retired military veteran. He lives in Hudson, Fla., with his wife, Myscha, and their dog, Maggie. He blogs about astronomy, science and science fiction at