What you may have heard

Standing too close to the microwave can increase your risk of developing cancer.

What science tells us

Microwaves do not emit enough radiofrequency radiation to be harmful to humans (ACS). Microwave ovens are designed so that the microwave radiation is contained within the oven itself. The oven only creates microwaves when the door is shut, and the oven is turned on.

Epidemiological Evidence

When microwave ovens are in good condition and are used according to instructions, there is no evidence that they pose a health risk to people.

Laboratory Evidence/Supporting Evidence

There are very limited animal or laboratory studies that look into the relationship between microwaves and cancer.

IARC Carcinogen Classification:

Group 2B (possibly carcinogenic: if microwave is broken/open)

How to reduce your risk

The best way to reduce your risk is to ensure that your microwave is in good working condition. Replace your microwave whenever it is damaged, as this might allow radiation leakage that could be harmful to humans, if not addressed.

Bottom line

Using a microwave is not risky, as long as the microwave is in good condition.

What you may have heard

Heating plastic in the microwave or freezing plastic releases various harmful chemicals that may cause cancer.

What science tells us

Freezing tends to work against the release of chemicals. The Johns Hopkins Bloomberg School of Public Health stated, “Chemicals do not diffuse as readily in cold temperatures, which would limit the chemical release” (LAT). This means that freezing any type of plastic container poses no cancer risks.

Diethylhexyl adipate (DEHA) is found in some plastics and may be released when the container is heated (LAT). It is possible that substances used in the manufacturing process of plastics, such as DEHA, may leak into food during the heating process. But the FDA imposes strict regulations on plastic containers labeled as “microwave safe” (FDA).

Epidemiological Evidence

However, the Environmental Protection Agency has said that DEHA “cannot reasonably be anticipated to cause cancer; immunotoxicity; gene mutations; liver, kidney, reproductive or developmental toxicity; or other serious or irreversible chronic health effects” (Fillon et al.).

Laboratory Evidence/Supporting Evidence

There is no laboratory evidence that microwaving or freezing plastics increases your risk of cancer.

IARC Carcinogen Classification:

Group 3 (Not classifiable as to its carcinogenicity to humans: Di(2-ethylhexyl) adipate)

How to reduce your risk

The best way to reduce your risk is to microwave food in heat-resistant glass or ceramics that are labeled as microwave safe.

Bottom line

Levels of DEHA found in plastics have not been conclusively shown to be carcinogenic (cancer causing). However, plastic utensils and containers vary in their chemical makeup, and ongoing research may find links with specific chemicals and cancer.

What you may have heard

Warnings have been posted about cancer risks from drinking from plastic water bottles.

What science tells us

There has been concern of cancer risks from potential exposure to diethylhexyl adipate (DEHA), diethylhexyl phthalate (DEHP), or bisphenol A (BPA) that may be found in plastic water bottles.
The American Cancer Society has stated that viral messages warning against the use of plastic water bottles were not based on peer-reviewed research (ACS). In addition, the Environmental Protection Agency stated that DEHA “cannot reasonably be anticipated to cause cancer; immunotoxicity; gene mutations; liver, kidney, reproductive or developmental toxicity; or other serious or irreversible chronic health effects” (JNCI).

Epidemiological Evidence

According to the Cancer Research Center in the UK, there have been several studies stating that the chemicals found in plastic are safe to drink since the levels of exposure are very low (Cancer Research UK).

Laboratory Evidence/Supporting Evidence

Researchers examined 10 common brands of bottled water stored under different conditions. They concluded that temperature and sunlight exposure do play a role in degradation of phthalates over time, with freezing temperatures containing higher levels of DEHP. However, DEHP levels in the samples (between 0.296 and 1.778 mg/kg/day) were far below the EPA’s maximum safe dose of 20 mg/kg/day (Al-Saleh et al.). BPA is an industrial chemical that has been used to make plastic since the 1960s. These plastics are frequently used to make containers that store food and beverages. Based on animal studies, BPA exposure at high doses (more than 100 times the level designated safe by the FDA) is likely to cause negative health effects in the kidney and the liver. But the U.S. Food and Drug Administration (FDA) has declared that BPA is safe at the very low levels that may result from water bottle use (FDA). This is based on a review of hundreds of studies (many of which test even heating the plastic for hours at a time), but the FDA continues to monitor this research (JNCI).

IARC Carcinogen Classification:

Group 3 (not classifiable as to its carcinogenicity to humans: Bisphenol A diglycidyl ether (Araldite))

How to reduce your risk

The FDA, the regulatory food safety body, reported that BPA, DEHP, and DEHA pose no risk to human health from foodstuffs because current levels of exposure are well below the tolerable daily intake (FDA). However, if you are concerned about BPA exposure, choose stainless steel or glass water bottles instead. In addition, some, though not all, plastics marked with recycle codes 3 or 7 may be made with BPA.

Bottom line

There is not enough evidence to suggest that plastic water bottles cause cancer. However, not all plastic water bottles have the same chemical composition, and ongoing studies about exposure to specific components of water bottles are ongoing.

What you may have heard

Shampoo with formaldehyde is a carcinogen.

What science tells us

Many hair care products, such as shampoos and leave-in conditioners, contain formaldehyde or other variations, such as formalin and methylene glycol. When these products are heated, the formaldehyde is released into the air as a gas. This can occur by blow-drying, straightening, or curling the hair.
Formaldehyde is a colorless, strong-smelling gas that presents a health hazard when inhaled. 
According to the National Cancer Institute, when more formaldehyde is in the air than 0.1 part-per-million (ppm), some people may experience negative health effects, such as watery eyes; burning sensations in the eyes, nose, and throat; coughing; wheezing; nausea; and skin irritation (NCI).
Skin sensitization or allergic dermatitis can develop after repeated exposure to formaldehyde-related ingredients and when released into the air, it can cause irritation of the eyes, nose, and lungs (NCI).
The greater (and longer) the exposure to formaldehyde, the higher the health risks. For example, if a salon is not properly ventilated, both salon professionals and its clients are at risk of inhaling the released formaldehyde (FDA). OSHA issued a Hazard Alert to hair salon owners and workers about potential formaldehyde exposure and set a standard (29 CFR 1910.1048) limiting the allowable exposure in the air.

Epidemiological Evidence

Several human studies of formaldehyde suggest that long term exposure can cause hematolymphopoietic cancer s including leukemias and lymphomas (Swenberg et al.)

Laboratory Evidence/ Supportive Evidence

Several laboratory studies have also used rat models, which concluded that long term formaldehyde exposure results in nasal cancer (NCI).

IARC Carcinogen Classification:

Group 1 (carcinogenic to humans: Formaldehyde)

How to reduce your risk

If you are concerned about skin or eye irritation from products with formaldehyde, you may want to switch to products that do not contain these chemicals. Formaldehyde may not be listed on a product’s ingredients, but there are two formaldehyde-related ingredients that may produce similar effects: formalin and methylene glycol.
A number of websites, such as the Environmental Working Group’s Skin Deep Database or MADE SAFE, rate the safety of ingredients used in personal care products. These websites also post lists of brands that contain certain chemicals. The smartphone app Detox Me includes many tips to help you choose safer products.
A dermatologist and/or pharmacist may also be able to direct you to products that do not contain chemicals you wish to avoid.
You may report any adverse health reactions directly to the FDA using this link: FDA MedWatch Adverse Event Reporting System.

Bottom line

People who work in salons are at an increased risk of cancer due to repeated exposure to formaldehyde gas, which is produced when shampoos with formaldehyde are heated. Consider switching to formaldehyde-free shampoos.

What you may have heard

Shampooing with products that contain sodium lauryl sulfate (SLS) cause cancer.

What science tells us

SLS is a cleaning agent and surfactant that is used in many personal care and cleaning products.

Epidemiological Evidence

While SLS chemicals may cause eye irritation (or eye damage in high-enough quantities) and skin irritation when it stands alone, there is no evidence either way about whether sodium lauryl sulfate is a carcinogen. This has been confirmed by numerous government and international agencies, such as the International Agency for Research on Cancer (IARC), the U.S. National Toxicology Program, the California Proposition 65 List of Carcinogens, the U.S. Environmental Protection Agency, and the European Union (Bondi et al.).

Laboratory Evidence/ Supportive Evidence

Several laboratory-based studies conducted on mice showed signs of skin irritation but did not show a cancerous effect when exposed to sodium lauryl sulfate (Rovira et al.). 
 

IARC Carcinogen Classification:

Not classified

How to reduce your risk

While SLS may not be cancer-causing, to avoid any skin or eye irritation, experts suggest switching to products that do not contain these chemicals. A number of websites, such as the Environmental Working Group’s Skin Deep Database or Nontoxic Certified’s MADE SAFE, and apps like Clearya and DetoxMe, rate the safety of ingredients used in personal care products; these tools also post lists of brands that contain each type of chemical.

Shampoos that do not contain SLS are clearly marked on the label and can be located in any supermarket or pharmacy. A dermatologist and/or pharmacist may also be able to direct you to products that do not contain chemicals you wish to avoid.

Bottom line

SLS is not a carcinogen, yet there are many platforms that provide information and alternative products if the chemical causes eye or skin irritation.

What you may have heard

Inhalation of diesel exhaust can cause cancer.

What science tells us

Diesel is a type of fuel derived from crude oil and is used in most large engines (such as trucks, trains, buses, construction equipment, and ships). The gas portion of diesel is made up of carbon dioxide, carbon monoxide, nitric oxide, nitrogen dioxide, sulfur oxides, and hydrocarbons (such as polycyclic aromatic hydrocarbons or PAHs). The soot portion of diesel exhaust is made up of particles (such as carbon, organic compounds such as PAHs, and traces of metallic compounds).

Epidemiological Evidence

In human studies, workers exposed to diesel exhaust have shown significant increases in risk of lung cancer (ACS). Both the International Agency for Research on Cancer (IARC) and the Environmental Protection Agency (EPA) view diesel exhaust as carcinogenic to humans.

Laboratory Evidence/Supporting Evidence

Both the gas and soot portions of diesel fuel can cause DNA changes in the lab (which can lead to cancer), and long-term exposure to diesel can cause lung cancer in lab animals (ACS). Some studies have shown that exposure to diesel exhaust and long-term inhalation has caused lung cancer in animals (Heinrich et al.). 

IARC Carcinogen Classification:

Group 1 (carcinogenic to humans).

How to reduce your risk

People are most often exposed to diesel exhaust on the roads and highways, or in certain occupations. As a result, organizations such as the EPA have taken some steps to reduce diesel emissions on the highway through legislation, and experts in this subject advocate for additional exposure reductions.

In terms of exposure in the workplace or in your own vehicle, try to reduce the time you are exposed to diesel exhaust, and reduce your time spent idling, as this can be very dangerous, especially in enclosed, indoor spaces (ACS).

Bottom line

Diesel exhaust is carcinogenic. Vehicles are required to meet federal guidelines for exhaust systems to reduce diesel emissions. Avoid older exhaust systems as they can be dangerous, especially in enclosed spaces. Choose vehicles with low emissions, including electric vehicles, and support national policies to reduce emissions to further reduce risks.

What you may have heard

The U.S. National Institute of Environmental Health Sciences (NIEHS) stated that the health risk from extremely low frequency (ELF) radiation poses a weak health risk: the radiation is not entirely safe, yet it is still a potential carcinogen (ACS, NIEHS).

What science tells us

Radiation exists across a spectrum from very high energy to very low energy. High-energy radiation includes X-rays and UV rays. Both X-rays and UV rays have the potential to damage cell DNA, which can lead to cancer. Power lines produce low frequency non-ionizing radiation from electric and magnetic fields. There is limited evidence that exposure to this type of radiation is associated with cancer.

Epidemiological Evidence

ELF radiation, such as what is found in power lines or household devices (like refrigerators and vacuum cleaners), does not have enough energy to damage DNA.  According to the American Cancer Society, there is no evidence that exposure to ELF radiation causes cancer (ACS). The International Agency for Research on Cancer (IARC) has similar findings, but they divided ELF radiation into two categories: electric and magnetic. IARC stated that there is not enough evidence to conclude whether extremely low frequency electric radiation in humans is carcinogenic, and that extremely low frequency magnetic radiation in humans is possibly carcinogenic (ACS, IARC). Children with the highest levels of exposure have a slight increase in risk for leukemia compared to children with the lowest levels of exposure (ACS, IARC).

Laboratory Evidence/Supporting Evidence

There are limited laboratory studies on power lines and the risk of cancer. More research is needed to further examine the relationship between the two.

IARC Carcinogen Classification:

Not classified.

How to reduce your risk

It is not clear that exposure to ELF radiation is harmful, but there are steps you may take to decrease your exposure. The NIEHS recommends that people find out where their ELF exposure is coming from and limit the time spent near the sources. ELF radiation from power lines, for example, decreases significantly as distance from the power line increases. The farther away you are, the safer you are from the radiation.

Bottom line

It is not clear that extremely low-frequency radiation causes cancer, but it does pose somewhat of a health risk. People should take steps to decrease their exposure.

What you may have heard

People who fly frequently, like pilots and flight attendants, are at higher risk for cancer.

What science tells us

Air crew are exposed to higher levels of radiation (specifically cosmic ionizing radiation, a type of radiation that comes from outer space). Cosmic ionizing radiation is known to cause cancer, and aircrew have the largest average exposure out of all radiation-exposed workers in the United States (CDC).  Air crew are also often subject to sleep cycle disruptions.

Epidemiological Evidence

According to the Centers for Disease Control and Prevention (CDC), both male and female crew members may be at increased risk for skin cancer, female crew members are at increased risk for breast cancer, and male aircrew have an increased risk of both Kaposi sarcoma and non-Hodgkin lymphoma (CDC). While there is enough evidence to support these facts, scientists are still unsure why this is true, though they do have some theories, which follow.

• UV radiation from sun exposure is a major risk factor for malignant melanoma, and UV radiation is significantly stronger at higher altitudes. Windows on commercial aircrafts block some radiation but not all (CDC).
• This population gets exposure to elevated levels of cosmic ionizing radiation (CDC).
• Circadian rhythm (sleep cycle) disruption from traveling across time zones, and working when others would normally be asleep (CDC), may be associated with elevated cancer risk.
• There may be differences in non-flight-related exposures outside the workplace (i.e., aircraft) (CDC).

Laboratory Evidence/Supporting Evidence

Currently, there is limited laboratory evidence that explains a relationship between airplane flying and increased cancer risk.

IARC Carcinogen Classification:

Group 1 (carcinogenic to humans: ionizing radiation)

How to reduce your risk

The CDC recommends that crew members try to reduce their time on very long flights, flights at high latitudes, or flights that go over the North and South Poles. These flights would result in the highest levels of radiation exposure (CDC).

To reduce your risk of skin cancer, protect your skin from the sun. There are many ways you can reduce your risk of skin cancer from UV radiation exposure: stay out of the sun/in the shade (especially during the middle of the day); wear clothing that covers your arms and legs; wear a hat with a wide brim; and wear sunglasses that block both UVA and UVB rays. Finally, watch for abnormal moles and talk to your doctor if any appear, as these moles may develop into melanoma (CDC).

Bottom line

Aircrew are at increased risk for both skin and breast cancers. The CDC recommends aircrew try to reduce their levels of radiation exposure.

What you may have heard

Interior or exterior house painting is associated with cancer.

What science tells us

Paint chemicals contain thousands of chemical compounds. The main organic solvents used in paints are toluene, xylene, aliphatic compounds, ketones, alcohols, esters, and glycol esters. The amount of volatile organic compounds (VOCs) released are similar to those of water-based paints (Chen et al.).
People who work in the paint industry are exposed to the chemicals found in paint products during their application and removal. In the past, exposure to hazardous substances often exceeded current occupational limits, but exposure levels have greatly decreased over time.

Epidemiological Evidence

Occupational exposure as a painter is classified as a Group 1 carcinogen by the International Agency for Research on Cancer (IARC) based on increased risk of lung cancer, urinary bladder cancer, and mesothelioma (IARC). But the IARC Working Group could not identify any particular agent in paint that increases cancer risk.

There is some evidence of a link between childhood leukemia and paint chemical exposure, but more research is required because current studies have inconsistent results.

Laboratory Evidence/Supporting Evidence

There is some toxicology evidence that organic solvents can cause cancer in animal studies. Some of the studies used solvent mixtures, so further research is required to see if there is one specific organic solvent that is the main cause. Researchers concluded that DNA damage occurred when exposed to these organic solvents (Lynge et al.).

IARC Carcinogen Classification:

Group 1 for Cadmium, Group 2A for inorganic lead, Group 2A for styrene, Group 2 for Benzene, Group 3 (for Xylenes), Group 3 (for Toluene), Group 3 for Chromium. All are ingredients in paint.

How to reduce your risk

Paint chemical exposure poses the greatest risk in a workplace setting. If you work with paint on a regular basis, it is important to wear masks and other protective gear to avoid exposure. In addition, during the first couple of days after paint is applied, keep away from it and increase ventilation out of the indoor space (Chen et al.). Don’t paint your home while you’re pregnant.

Bottom line

Occupational paint exposure is classified as a Group 1 carcinogen by IARC. If you have regular exposure to freshly applied paint, make sure to wear a mask, work in a well-ventilated area, or use other protective measures.

What you may have heard

Exposure to asbestos causes cancer.

What science tells us

Asbestos was a construction material (used primarily in insulation) and can be found in buildings built before 2000. The International Agency for Research on Cancer (IARC) has labeled asbestos as a known carcinogen. It causes cancer by scarring lung tissue whenever its fibers are breathed in. The two most common types of cancer linked with asbestos are lung cancer and mesothelioma (ACS). There is also a link between asbestos and ovarian and laryngeal cancer rates.

Epidemiological Evidence

Several epidemiological studies have shown that exposure to asbestos increases the risk of mesothelioma, a type of lung cancer. One study based in Taiwan among workers in the jade processing industry showed an increased risk of lung cancer (Lin et al.). Another population-based cohort study also found that those living near asbestos producing manufacturing plants also had higher rates of mesothelioma and lung cancer compared to the general population (Zha et al.). Case control studies also found that those who were exposed to asbestos had a higher risk of developing lung cancer (Minowa et al.).

Laboratory Evidence/Supporting Evidence

Several animal studies have shown that exposure to asbestos is harmful in animals and can cause several types of cancers including mesothelioma.

IARC Carcinogen Classification:

Group 1 (Carcinogenic to humans)

How to reduce your risk

Since the early 2000s, many countries have banned the use of asbestos in construction, with active efforts to remove asbestos from buildings built before 2000 as well, especially in the United States (ACS).

To ensure that your exposure to asbestos is low, check when your home, workplace, and any other buildings you’re often in were built. If any of them were built before 2000, check to see if they have been renovated and/or inspected for asbestos. Most buildings have, but if you are unsure, contact the ACS, as they spearhead the removal and testing of asbestos (NIOSH).

Bottom line

Asbestos is a known carcinogen, but for most people, asbestos exposure is not a concern. To ensure that your exposure is low, verify that your home and workplace are up to national standards.