What you may have heard

You may have seen a viral TikTok video claiming that tampons contain an ingredient called titanium dioxide, which is responsible for increasing the risk of cancer.

What science tells us

Titanium dioxide is used as a pigment in the thread attached to tampons. Less than 0.1% of titanium dioxide is used in the total ingredients of tampons. Because exposure levels are very low, it is likely this is a very low carcinogenic risk.

Epidemiological Evidence

Currently, there are no high-quality epidemiological studies that establish that titanium dioxide in tampons is linked with an increased risk of cancer.

Laboratory Evidence/ Supportive Evidence

One laboratory study looked into the relationship between exposure to titanium dioxide in rats. They found that when rats were exposed to high levels of titanium dioxide, lung cancer developed (Driscoll).

IARC Carcinogen Classification:

2B (possibly carcinogenic to humans)

How to reduce your risk

You can lower your risk of exposure to titanium dioxide by opting to use tampons that are free of dyes, fragrances, and bleaching.

Bottom line

Based on the current evidence, titanium dioxide exposure from tampon use does not cause cancer.

What you may have heard

Exposure to pesticides can increase the risk of developing cancer.

What science tells us

Pesticides are typically used in food production and to treat insect infestation. Mosquitos, ticks, rats, and mice can carry diseases, and pesticides can be used to limit human exposures to these pests (EPA). 

Epidemiological Evidence

It is very difficult to measure exposure to pesticides, therefore randomized control trials cannot be conducted. Most exposures that could be relevant to cancer risk may have occurred a long time ago, and it is nearly impossible for an individual to accurately report what exposures they may have had many years ago.  Occupational studies have been the most useful in understanding the effects of pesticide in the workplace (for example, among agricultural workers), and many have reported that high exposure to pesticides can increase the risk of many types of cancers such as: brain, breast, kidney, lung, ovarian, pancreatic, and prostate cancer (Bassil et al.).

Laboratory Evidence/ Supportive Evidence

Several pesticides have been shown in toxicology studies to be cancer causing. DDT in laboratory studies was shown to cause tumors in the livers in rats and mice. 

Lindane has shown to be suggestive of causing cancer but requires more data to further evaluate. It was shown to cause lung tumors (Burns et al.)

Glyphosate

Epidemiological Evidence

Most epidemiological studies and the balance of the epidemiological evidence has shown that glyphosate, a common pesticide used to kill weeds, is not carcinogenic in humans (EPA). However, there remains much controversy about these findings and conclusions about the carcinogenic role of glyphosate under usual human exposure levels is not considered resolved by some.

Laboratory Evidence/ Supportive Evidence

Laboratory evidence generally concur with the epidemiological evidence that exposure to glyphosate based pesticides are generally safe among animals (Jarrell et al.). 

IARC Carcinogen Classification:

2A (Probably carcinogenic to humans: Glyphosate)

How to reduce your risk

You can limit the use of pesticides by opting to use non-chemical methods to control the number of pests in the yard. Mechanical traps can be used to catch unwanted insects, and the introduction of beneficial insects into the yard can help reduce the presence of aphids. Ladybugs will reduce the presence of aphids. 

If using pesticides, make sure to follow the instructions on the bottle and wear protective clothing when spraying. Use gloves, protective eyewear, and make sure you are in a well-ventilated area. Keep children, pets, and toys away from the treated areas (NY Health).

Bottom line

Some pesticides are deemed harmful by IARC and the EPA and can cause cancer. While some pesticides like glyphosate are considered safe by the EPA, further research is needed to examine what other individual pesticides may be harmful.

What you may have heard

Commercially manufactured disposable chopsticks contain cancer-causing chemicals.

What science tells us

The claim that disposable chopsticks contain aflatoxin, a known carcinogen, is unproven. Aflatoxins are chemicals produced by certain fungi and are found on agricultural crops such as corn, peanuts, and tree nuts. People may be exposed to aflatoxins by eating contaminated plant products or by eating meat or dairy from an animal that ate contaminated feed. Aflatoxins have been found in some commercial peanut butter and sesame paste (NCI).

Epidemiological Evidence

The manufacturing of disposable chopsticks is highly regulated by the FDA and EPA, both of which help to ensure reduced exposure. There is currently no epidemiological evidence that aflatoxins are present in disposable chopsticks.

Laboratory Evidence/Supporting Evidence

There is no toxicological evidence that aflatoxin is found in disposable chopsticks.

IARC Carcinogen Classification:

Not classified

How to reduce your risk

Wooden chopsticks do not contain aflatoxin and are safe to use for food consumption.

Bottom line

There is no evidence that disposable chopsticks are linked to an increase in cancer risk.

What you may have heard

The use of bug spray with DEET can cause cancer.

What science tells us

Much of the concern about insect repellents is with one of its most common ingredients: N,N-diethyl-meta-toluamide, known commonly as DEET. DEET gives bug spray its strong chemical smell, which is used to repel biting insects, such as mosquitos, ticks, and fleas.

Epidemiological Evidence

The Environmental Protection Agency (EPA) has concluded that DEET is not a human carcinogen. With high exposure levels, such as in a chemical spill, there may be damage to the central nervous system. Additional evidence about cancer risk is unclear.

Laboratory Evidence/Supporting Evidence

Some animal studies have reported an increased cancer risk when exposed to DEET (NPIC). However, several larger studies with long follow-up have been conducted on animals which did not show an increase in tumors when exposed to bug spray with DEET (ATSDR).

IARC Carcinogen Classification:

Not classified.

How to reduce your risk

Always use insect repellents as directed. Only apply insect repellents to exposed skin and/or clothing, and do not apply near the eyes or mouth. When using sprays, do not spray directly into the face—spray on the hands first, and then apply to the face. 

The EPA has approved the use of insect repellents that do not contain DEET. For example, another ingredient in insect repellent and industrial pesticides is permethrin. The Environmental Protection Agency (EPA) concluded that permethrin (and the associated chemicals resmethrin and d-phenothrin) can be used for public health mosquito control without posing unreasonable risks to human health (EPA). These alternatives could give you peace of mind if you would prefer to avoid DEET. The smartphone app Detox Me also has many tips to help you choose safer products.

Bottom line

Insect repellents containing DEET do not have a cancer-causing effect in humans, but alternatives are available that do not contain DEET.

What you may have heard

Loom bands were pulled from shelves due to concerns about cancer risk.

What science tells us

Rainbow Loom is a plastic device used to weave small, colored rubber bands (loom bands) into jewelry. Loom bands were pulled from the shelves after they were found to contain high levels of phthalates. This is concerning because phthalates can cause health problems if ingested over time.  Loom bands are mainly used by children, and there is a risk that the band will end up in a child’s mouth.

Epidemiological Evidence

Phthalates have been well-studied in animal models, and prenatal exposure to phthalates was found to have harmful effects on the reproductive tract of male offspring (Engel et al.). Over the past 10 years, studies have shown that human prenatal exposure to phthalates affects children’s brain development and increases their risk for learning, attention, and behavioral disorders (Engel et al.). There are still many questions about how phthalates may affect people’s health, and more research is needed to assess the health risks of phthalates.
There are many types of phthalates, and only one is classified as a possible cause of cancer by the International Agency for Research on Cancer (IARC) and “reasonably anticipated to be a human carcinogen” by the National Toxicology Program (NTP): diethylhexyl phthalate (DEHP). DEHP was found in loom bands at higher concentrations than the legal limit. However, there has not been enough data collected in humans to determine if cancer risk in humans is associated specifically with loom band exposures.

Laboratory Evidence/Supporting Evidence

In animal models, DEHP was found to cause liver cancer, benign testicular tumors, and benign pancreatic tumors

IARC Carcinogen Classification:

Group 2B (possibly carcinogenic to humans: Di(2-ethylhexyl)phthalate) and Group 3 (Not classifiable as to its carcinogenicity to humans: Butyl benzyl phthalate)

How to reduce your risk

As previously mentioned, loom bands were pulled from shelves due to concerns about cancer risk. Exposure is highest when eating or drinking foods that contain phthalates (CDC). Children crawling around, touching items that contain phthalates, and putting their hands in their mouths are of serious concern. To ensure phthalate exposure is low, don’t eat or drink (or in the case of loom bands, don’t allow children to place the bands in their mouths) products known to contain higher levels of phthalates. These products include certain toys, vinyl flooring, vinyl wall covering, detergents, lubricating oils, food packaging, pharmaceuticals, blood bags and tubing, and personal care products, such as nail polish, hair sprays, aftershave lotions, soaps, shampoos, etc. (FDA).

Bottom line

More research is needed to assess the relationship between phthalate exposure and cancer risk. However, phthalate exposure is linked to other health conditions, such as reproductive health defects and the brain development of children. If your child is using loom bands, ensure that they don’t put the bands in their mouths and that they wash their hands after touching them.

What you may have heard

Burning scented candles emits cancer-causing chemicals.

What science tells us

Burning scented candles could lead to cancer-causing exposures through wax and wicks. Some aromatherapy candles are made of paraffin, which is a petroleum byproduct that releases carcinogenic soot when burned (Green America). At high exposure levels, this soot can also cause or aggravate respiratory problems and damage the inside of your house (for example computers, electrical appliances, ductwork). Harmful concentrations of other pollutants that may be found in scented candles (for example, formaldehyde, carbon dioxide, carbon monoxide, particulate matter, and volatile organic compounds ) are also found in homes that burn scented candles regularly (Adamowicz et al.).

In addition, candles made before 2003 may have lead-core wicks. A candle with a lead-core wick releases five times the amount of lead considered hazardous for children and exceeds EPA pollution standards for outdoor air (Green America). No amount of lead is safe for humans and high lead exposure has been linked to hormone disruption, behavioral problems, learning disabilities, and many other health problems (CDC), including cancer.

Epidemiological Evidence

There is limited epidemiological evidence about exposure to scented candles and cancer risk.

Laboratory Evidence/ Supportive Evidence

Laboratory evidence has shown that candles themselves are not a concern. A 2007 study found that the chemicals that make up candles are well below the threshold value of causing health problems (AECM). However, burning of candles releases volatile organic compounds (VOCs) into the air, which can be harmful. A 2014 laboratory study showed that the amount of VOCs released from burning candles is very low, and not large enough to be harmful to human health (Petry et al.).

IARC Carcinogen Classification:

Not classified

How to reduce your risk

There are plenty of non-toxic candle alternatives: 100% beeswax candles with cotton wicks are free of toxic chemicals, as are candles made from 100% vegetable-based or soy waxes (Green America). To reduce soot, regardless of the type of candle, trim wicks to ⅛ of an inch. Candle-free aromatherapy is another way to release pleasant scents without any harmful byproducts. Essential oils are non-toxic and can be released through a diffuser, a ring burner, or added to a warm bath.

Bottom line

Occasional use of scented candles is unlikely to have carcinogenic effects, but frequent burning of some non-vegetable or non-soy-based scented candles may increase cancer risk. Pick non-toxic alternatives when buying scented candles.

What you may have heard

Antiperspirants and deodorants contain cancer-causing substances that are absorbed, particularly after shaving.

What science tells us

Antiperspirants are classified as a drug that helps reduce the amount of sweat produced. The eccrine gland produces sweat and antiperspirants can block the production of sweat using an aluminum-based product (WebMD). Deodorants are used to prevent or mask body odor. Scientists are studying whether fragrance, preservatives, and other ingredients in antiperspirants and deodorants may increase breast cancer risk. Questions about whether there is a difference in risk for women who shave their underarms or use antiperspirant or deodorant products that contain aluminum are still being researched.

Natural deodorants boast that they are better for people than traditional deodorants. However, there is no evidence that regular deodorants are worse for your health than natural deodorants (NY Times). Also, the ingredients in natural deodorants are no better for your microbiome and may be less effective than traditional deodorants (NY Times).

Epidemiological Evidence

Several theories have been suggested about how antiperspirants and deodorants might cause breast cancer. The most recent review of antiperspirants or deodorants and breast cancer showed no evidence for a link (Osto 2022). However, studies have reported mixed results, so more studies are needed to confirm the current data.

The American Cancer Society noted that while a 2004 study showed the presence of parabens in breast cancer tissue, they produce weak estrogen-like properties. Estrogen that is naturally produced in the body (or through hormone replacement) are much stronger, and therefore play a larger role in risk of breast cancer.

This topic gained attention in 2021 when a study reported that parabens, a preservative used in deodorants that mimics estrogen, was found in breast tumors. Scientists are not sure what this study means about the development of breast cancer (NCI).

Laboratory Evidence/Supporting Evidence

One animal study that examined the uptake of aluminum in deodorant found some evidence of chromosomal breakage (Tenan et al.). However, the current research is still limited. Additional research is needed to further investigate the relationship between antiperspirants and cancer risk.

IARC Carcinogen Classification:

Not Classified

How to reduce your risk

There are many known risk factors that are linked with breast cancer. Drinking alcohol is clearly linked to an increased breast cancer risk, and risk increases with the amount of alcohol. Women who have one alcoholic drink a day have a small (7-10%) increase compared with non-drinkers. This risk increases to 20% in women who have 2-3 drinks a day (ACS).

Another known risk factor is being overweight or obese after menopause. Especially after a woman reaches menopause, most of a woman’s estrogen comes from fat tissue. Excess fat can raise estrogen levels and increase risk of breast cancer. Post-menopausal women who are overweight or obese also tend to have higher insulin levels, which are linked with some cancers. These risk factors may be lowered with physical activity and a healthy diet, which reduce the risk of breast cancer (ACS).

Bottom line

Deodorants and antiperspirants sometimes contain ingredients linked to cancer. Some studies of antiperspirants have provided conflicting results, though, so more research is needed.

To watch a brief video about deodorant and breast cancer risk, click below.

What you may have heard

Cosmetics and their ingredients are frequently discussed in the media as being associated with cancer.

What science tells us

The FDA defines cosmetics as “articles intended to be rubbed, poured, sprinkled, or sprayed on, introduced to, or otherwise applied to the human body…for cleansing, beautifying, promoting attractiveness, or altering the appearance” (FDA). This includes a wide range of products from moisturizers to soaps and nail polish. 

Some ingredients in cosmetics have been identified as toxic (for example, certain hair dyes). The ingredients in cosmetics are routinely tested for short-term health problems, such as skin and eye irritation and allergic reactions. The FDA mandates that cosmetics be safe for consumers, but it does not have the authority to require companies to test cosmetic products before they are put on the market (FDA). Short-term effects often become clear once a product reaches the market, and the FDA can request that the company recall the product.

However, cosmetics are seldom tested for long-term health effects. As a result, it is sometimes unknown if the individual ingredients cause health problems alone or when combined in cosmetic products. It can take many years or even decades after exposure to a carcinogen for cancer to develop (FDA). It is not always feasible for researchers to conduct studies that extend this long on particular products, and even then, scientists don’t usually test each combination and dose of cosmetic products to establish a causal link to cancer. Ingredients and combinations also change frequently.

Epidemiological Evidence

It is still unclear whether the ingredients in cosmetics increase cancer risk because most ingredients and combinations of ingredients in cosmetics have not been thoroughly tested in well-designed epidemiological studies. In part, the inability to accurately assess or measure what cosmetic products were used limits this area of research.

Laboratory Evidence/Supporting Evidence

Many (but not all) cosmetic ingredients have been tested in animals for short-term health consequences. Additional research is also needed to determine the effects of certain ingredients on cancer risk.

IARC Carcinogen Classification:

Not classified.

How to reduce your risk

There are many gaps in research, including how ingredients in cosmetics can be absorbed and built up in the body. The FDA requires that products that have not been tested carry the label, “Warning—The safety of this product has not yet been determined” (FDA). If you would like to reduce your potential risk, keep an eye out for these warnings. You may choose to avoid products with certain ingredients, reduce the number of cosmetics you use, or avoid cosmetic use altogether. There are a number of websites that can help inform your cosmetic choices. For example, some websites list either cosmetics that are known to contain harmful ingredients (such as the California Safe Cosmetics Program) or cosmetics with safe ingredients (such as Skin Deep).  Smartphone apps like Clearya and Detox Me include many tips to help you choose safer products.

Bottom line

Research has shown that certain hair dyes are linked with cancer, and other cosmetic products may contain carcinogenic chemicals. Uncertainties remain because of lack of testing for carcinogenicity by companies and regulatory agencies, and lack of information about products’ chemical effects (for example endocrine disruption) that may be related to cancer. All cosmetic products should only be used as designated on the label.

What you may have heard

Wearing bras causes cancer.

What science tells us

Epidemiological Evidence

There has been concern that bra-wearing changes how lymph nodes remove waste and toxins from the breast. However, there is no epidemiological evidence to support this claim. 

The Fred Hutchinson Cancer Research Center in Seattle interviewed over 1,000 women with the most common types of breast cancer and 500 randomly selected women without breast cancer. The investigators found no difference between those who did wear a bra and those who did not (Harvard Health). An earlier Harvard School of Public Health study also found no association when they asked 15,630 women about their bra usage and breast cancer history (Hsieh et al.). These two studies suggest that there is no association between bra use and breast cancer.

Laboratory Evidence/Supporting Evidence

There is no laboratory evidence that links bras to cancer risk.

IARC Carcinogen Classification:

Not classified.

How to reduce your risk

There are several known risk factors associated with breast cancer. Drinking alcohol is clearly linked to an increased risk of breast cancer, and that risk increases as the amount of alcohol consumed does. Women who have one alcoholic drink a day have a small (7-10%) increase compared with non-drinkers; this risk increases to 20% in women who have 2-3 drinks a day (ACS).

Another known risk factor is obesity after menopause, or having a BMI of 30.0 or higher. After a woman reaches menopause, most of a woman’s estrogen comes from fat tissue. Excess fat can raise estrogen levels and increase the risk of developing breast cancer. Women who are overweight or obese also tend to have higher insulin levels, which are associated with some cancers. Both of these risk factors may be mitigated with physical activity and a healthy diet, which reduce the risk of breast cancer (ACS).

Bottom line

There is no epidemiological evidence that supports an association between bra use and breast cancer.

For more information, watch this short video about bras and cancer risk from the Dana-Farber Cancer Institute and follow the links below.

What you may have heard

Keeping your phone close to your body or head can increase your risk of cancer.

What science tells us

Phones emit RF (Radiofrequency) waves, which are a form of non-ionizing radiation. This means that they do not have enough energy to directly damage DNA inside cells and cause cancer (ACS, NCI). The closer the phone is held to the body, the greater the expected exposure to RF waves. Many other factors affect the amount of energy a person is exposed to, such as:

• amount of time a person is on the phone and the nearness of the cell phone to the user’s body (e.g., head);
• distance and path to the nearest cell tower: the farther the distance from the nearest cell tower, the more energy is required to maintain the signal;
• amount of cell traffic in the area at a time: the more traffic, the more energy is required to maintain the signal; and
• model of phone being used.

Epidemiological Evidence

Many studies have evaluated whether there is a link between cell phone usage and cancer, however, the results are not conclusive (NCI). Most international organizations deem cell phone usage to be at most only a potential risk to cancer and at the least, insufficient evidence to comment.

Laboratory Evidence

Currently, there is no laboratory evidence linking cell phone use to increased risk of cancer.

IARC Carcinogen Classification:

Group 3 (Not classifiable as to its carcinogenicity to humans:  Radio-frequency electromagnetic fields).

How to reduce your risk

It is not clear whether decreasing the amount of time spent on the cell phone (ACS), using the speaker mode or a hands-free device, or texting instead of talking on the phone would decrease cancer risk. Although studies are inconclusive, decreasing your exposure to RF waves will lessen the chances that you are increasing your cancer risk.

Bottom line

RF waves used in cell phones do not have enough energy to damage DNA, so this mechanism is not likely to cause cancer. However, there is insufficient evidence to conclude a link between cancer risk and cell phone use.

To watch a short related video on wireless and bluetooth technology and cancer risk, click play on the video below.