15 Breast Cancer Risk Factors

October is Breast Cancer Awareness Month. Learn the often-surprising risk factors that may increase risk of developing breast cancer – and, importantly, how you can prevent you (and your daughter) from getting breast cancer.


start preventing breast cancer early (for your daughter's sake)
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Start Preventing Breast Cancer Early (for Your Daughter's Sake)

What causes breast cancer? Anyone who has been diagnosed with the disease, or watched a friend or family member have to deal with it, wants to know. Research has taught us that many widely understood risk factors play a role, including our genetic makeup and whether or not we've had kids or breast-fed. But these risk factors don't explain it all. A substantial body of scientific evidence indicates that exposures to common chemicals and radiation, alone and in combination, may contribute to the unacceptably high incidence of breast cancer.

Not only are exposures to particular chemicals and mixtures important, but the timing of these exposures may be critical. Breast tissue is developing from prenatal stages through the time that a woman gives birth and breastfeeds, and breast structures that have not gone through the full sequence of development are particularly sensitive to the detrimental effects of environmental toxins. The cancer usually doesn’t show up until adulthood, but the stage may well have been set in the womb, or early in childhood.

What can we do? This feature will help you identify some known and suspected breast cancer risk factors. Some of these tips apply mostly to middle aged or older adults – both women and men – who are at the age when diagnosis is most common. Other tips will help parents protect their children, even in the womb.

Janet Gray is the director of the Environmental Risks and Breast Cancer project at Vassar College, in Poughkeepsie, N.Y. and a board member of the Breast Cancer Fund. The Environmental Risks and Breast Cancer project is designed to communicate known and suspected environmental triggers for breast cancer to the general public.

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Avoid Weed Killers

Many common herbicides (weed killers) have been linked to a variety of human diseases, including breast cancer. It probably shouldn’t surprise us that these compounds can be dangerous; they are designed to kill plants with which we share many common biological systems! Yes, humans and grass actually both depend on estrogen for proper regulation of cellular activity.

Several herbicides are known endocrine disruptors (they disrupt natural hormone-signaling pathways); endocrine disrupting chemicals have been implicated in increased risk for breast cancer, as well as other health problems. In addition to worrying about adult exposures to these chemicals, it is particularly important to not use toxic weed-killers on lawns where children play. Young children often spend much more time on the lawns, and tend to have direct exposure to the chemicals through walking barefoot and rolling in the grass. Because they are smaller, the exposure to chemicals actually leads to greater levels of the toxins in their bodies than for adults.

What’s this all got to do with breast cancer? We now know that exposures to toxic chemicals very early in life may predispose an individual to be more likely to be diagnosed with breast cancer, as well as many other disorders, many years – or decades – later.

Alternatives to use of herbicides include perhaps the most obvious, letting your lawn develop its natural combination of green (and other) plants. Frequent mowing leads to lawns that look grasslike in color, if not completely in content. Weeding by hand, of course, is great exercise. Use of ground cover, in place of grass, can provide an aesthetically pleasing look that is relatively weed-resistant and easier to care for than manicured grass coverage. And in limited spots, vinegar, salt, soapy water, and rubbing alcohol may help control weeds.

See 21 Organic Lawn Care Tips from a Real Expert.

Use Natural Pesticides

Many common pesticides (such as ant, roach and mice poisons) have been linked to a variety of human diseases, including breast cancer. It probably shouldn’t surprise us that these compounds can be dangerous; they are designed to kill insects with which we share many common biological systems!

Several pesticides are known endocrine disruptors (they disrupt natural hormone-signaling pathways), and through these mechanisms have been implicated in increased risk for breast cancer. In addition to effects by themselves, these chemicals have been shown to have additive effects with other kinds of endocrine disruptors. In other words, exposures to small doses of pesticides may have greater effects when people are also exposed to other chemicals to which we are all commonly exposed.

Unfortunately, when pesticides are applied in the home, they don’t just kill bugs and disappear. Rather they often stick around (for years or decades) and are found in the air and on the dust we touch and breathe, meaning that we all have sustained and multiple exposures to these toxic chemicals. And when we apply them outside, pesticides enter the air we breath, fall on the lawn on which we walk and our children play, and eventually seep into our water. The result can be devastating for the wildlife with which we share our world, and also may have significant impact on rates of human diseases, including breast cancer.

The best way to minimize insects inside and outside the home is through careful and regular cleaning. Integrated Pest Management (also known as IPM) approaches provide chemical-free (or low-chemical) strategies for protecting home environments, yards and agricultural crops. The University of California at Davis has published a good resource for learning more about IPM applications for the home and garden.

Choose BPA-Free Baby and Water Bottles

Bisphenol A, also known as BPA, is a chemical found in many food containers, and polycarbonate plastic water bottles. Unfortunately BPA leeches out of bottles and into the fluid you’ll be drinking.

BPA is a hormone-mimicking chemical and there is substantial scientific evidence linking exposures to BPA with the development of a number of health problems including breast cancer, as well as heart disease, diabetes and other metabolic problems, and learning disorders.

The detrimental effects of BPA may be especially severe when developing fetuses and young children are exposed to the chemical, leading to lifelong increases in risk for cancer and other disorders. Avoiding BPA-contaminated products is therefore especially important for pregnant women and young children. But its pervasive effects as a synthetic hormone suggest that we all should take care to minimize our exposures to this chemical.

In place of plastic bottles, high-quality stainless steel bottles (look for "18/8" or "8/10" steel, which refers to the composition of the steel) can be purchased in many stores and online from Kleen Kanteen (which makes donations for sales of pink bottles to The Breast Cancer Fund) as well as several other sources. For infants and toddlers, Born Free and other companies now make baby bottles made of stainless steel or other substances that are free of BPA, phthalates, and other toxic chemicals.

Avoid Canned Food

In addition to being found in many plastic bottles, Bisphenol A is also found in the epoxy resin liner of most canned fruits and vegetables. The BPA from this lining has been shown to leach into the vegetables in the can. Studies have shown that amount leached is enough to cause breast cancer cells to grow and proliferate in the lab.

One company that makes BPA free canned beans is Eden Organic, showing that the technology is there to make cans for most fruits and vegetables without using BPA-contaminated products.

Another reason for buying fresh or frozen vegetables is that they tend to have few preservatives and less added sodium. And buying fresh vegetables means you can talk directly with the farmers to learn more about what pesticides and other chemicals they use (or don’t use) during the growing season.

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Minimize Car Exhaust

Polycyclic aromatic hydrocarbons (known as PAHs) are products of incineration found in air pollution, vehicle exhaust (particularly diesel), tobacco, smoke and grilled foods. Exposures to PAHs, especially from vehicle exhaust and gasoline fumes, have been linked with increased incidence of breast cancer in both women and men.

A recent study in western New York examined air-monitoring records from 1959 to 1997 to establish PAH levels in residential areas. This case-control study of 3,200 women (ages 35 to 79 years) concluded that exposures to high levels of PAHs either at the time of their first menstrual period or at the time they first gave birth, were associated with an increased risk of post-menopausal breast cancer decades later.

Of course, don’t smoke! And avoid being close to others who are smoking; second hand smoke is a major source of PAHs.

When purchasing a car, especially a used one, make sure that the emissions system meets or exceeds government standards. In particular, check that the computer system controlling the car's emissions is fully functional and that the catalytic converter works properly. (Also check out the most fuel-efficient 2009 cars and SUVs and the weirdest car fuels that could replace gas.)

Finally, PAHs are also found in the char of heavily grilled meats and fish. So when grilling, use a slower roast method, and scrape off any char that results from cooking.

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Eat Clean Fish

Intake of certain foods that may contain high levels of PCBs and dioxins should be limited, especially for pregnant women and children. Both are known carcinogens that have been linked with increased risk for breast cancer. Although PCBs have been banned from production and use in the US since the 1970s, they remain in our environment, including our rivers and lakes. PCBs bioaccumulate, meaning they are more concentrated in predatory species than in prey, so they can be highly concentrated in fish at the top of the food chain.

If eating locally caught fish, eat smaller varieties such as bluegill, pumpkinseed, stream trout, smelt, and yellow perch. Limit consumption of fish that are fattier (and more likely to accumulate PCBs) like lake trout, or fish that are bottom dwellers like catfish. These latter species are more likely to be contaminated with chemicals including PCBs. Consult fish advisories published by the Environmental Protection Agency or state health and wildlife agencies before eating fish caught in local waters. Before heading to the fish counter, consult nonprofit groups that monitor contaminant levels in fish.

Some farmed salmon and sea bass have been shown to have particularly high levels of PCBs; opt for wild fish for these varieties.

In general, careful preparation and cooking can reduce the amount of PCBs consumed. Fillet fish by removing as much fat as possible. Also cook using methods such as baking or broiling in a pan with a rack, rather than frying – frying may actually seal some of the toxic chemicals within the remaining fat of the fish, while other methods may ease the cooking off of natural fats, leading to the dripping out of accumulated chemicals.

Use Natural Sunscreens

We all know that we need to be careful when we are out in the sun for any substantial period of time. Too much exposure to direct sun (UV light) has been linked to increased rates of skin cancer.

But many sunscreens contain the active ingredient titanium oxide. One problem is that dioxin, a carcinogenic agent linked to increases in breast cancer, is released during its production. Small amounts of dioxin are often found in sunscreen products.

Many sunscreens also contain chemicals that mimic estrogen, the female hormone. Theses endocrine disrupting chemicals are accumulating in both human and wildlife tissues, as we apply more and more sunscreen to our bodies and then often wash it off into the waters in which we swim. Examples of chemicals with estrogen-like activity that have been shown to increase rates of breast cell growth and proliferation in laboratory studies, an which are found in common sunsreens include:

  • 3-(4-methyl benzylidene)-camphor (4-MBC)
  • octyl-methoxycinnamate (OMC)
  • .

Like many other environmental chemicals that may affect health, the chemicals in sunscreens may have multiple effects. For example, application of sunscreens to the skin may increase the penetration of endocrine-disrupting herbicides into our bodies.

For safer alternatives to sunscreens that contain these chemicals, go to the Environmental Working Group’s SkinDeep database, or get a quick look at these 14 Natural Sunscreens.

Drink Safe Water

Although drinking fluids is absolutely crucial to good health, and water is often the healthiest – certainly the lowest-calorie – option, using tap water rather than bottled water is important for both our health and for the health of our environment. If taste is an issue, filtered tap water is a solution.

Commercial water bottles – including the small ones we carry around and then throw away, the larger gallon-sized bottles we may buy for our refrigerators, and the larger 5-gallon polycarbonate containers found in offices and other public spaces – often are made from plastics that leach chemicals like Bisphenol A, which is known to mimic hormones, and which has been linked to an increased risk for breast cancer and other diseases. Leaching of chemicals from plastic bottles is particularly common when the plastic bottles are warm, as can happen when bottles sit in the sun. If you are using a plastic bottle and the water or other fluid inside it smells "plasticky", don’t drink it! Your nose is telling you good information about the presence of contaminants in the water.

Of course, there are loads of other reasons for not drinking bottled water whenever possible. Tap water is often as safe or safer than bottled water, as public water sources are closely monitored and the results of quality testing on these waters are available to the public. Similar testing and disclosure are not required for bottled water.

And of course, the plastic required for commercial bought bottled water is a huge drain on natural petroleum resources, and adds enormously to our communities' waste burden.

To take water on the go, invest in a cheap, high-quality stainless steel water bottle, or another reusable BPA-free water bottle.

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Eat Soy (But Not Too Much)

Plant estrogens, also called phytoestrogens, are natural compounds found in many foods. There are two main groups: the isoflavones and the lignans. Isoflavones, which include genistein, are found in soy beans and are the most widely studied of the phytoestrogens. Lignans are found in flaxseed, cereals, fruits, and berries. Phytoestrogens are strikingly similar in chemical structure to the common estrogen estradiol and and can mimic many of the effects of the natural hormone. Most research on health effects of phytoestrogens, including effects on breast cancer risk, has been done on soy products and genistein.

Most (but not all) studies suggest that regular intake of soy, as a well-integrated component of a regular diet (as opposed to a dietary supplement like a pill), may be slightly protective against breast cancer. On the other hand, studies that look at regular consumption of soy during adolescence, again as part of a regular diet, provide significant protection against later breast cancer development. Some studies examining the effects of ingesting high levels of soy supplements (e.g., genistein pills or isoflavone protein extracts) suggest that this may lead to changes that increase the risk of breast cancer.

So eat a healthy, balanced diet that is rich in vegetables (preferably locally grown and pesticide-free!) including soy products. Introduce your children to soy products (soy flour, tofu, etc.) early in their development, as part of their regular diet. But stay away from concentrated or isolated forms of soy derivatives, including genistein pills.

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Choose Truly "Microwave-Safe" Containers

Despite the label on many plastic containers claiming that they are "microwave-safe," it is prudent to use either glass or ceramic bowls for heating foods in a microwave oven. Heating plastics can make chemicals used in their manufacturing to leach into your food. Even so-called "microwave safe" containers have been shown to leach Bisphenol A.

Laboratory studies with rats indicate that exposures to BPA, especially during prenatal through early adolescence, predispose an individual to increased risk for developing breast cancer. Most supermarkets now sell Pyrex or other glass food storage containers that are easy to heat, allow you to freeze, thaw and heat (in oven or microwave) food safely, and can be reused for years. When you do microwave your food, whether in glass or ceramic containers, cover the food with a piece of kitchen parchment paper, or other non-dyed, non-bleached paper product. Or just put a ceramic plate on top as a cover.

See 10 more "microwave safe" myths.

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Check Older Toys

In August 2008, Congress passed (and President Bush signed) the Consumer Product Safety Improvement Act, a bill that bans for the first time lead and several phthalates from children’s products, including toys. Phthalates are chemicals used in manufacturing plastics like the iconic rubber ducky soft and pliable. Many toys, teethers, and other objects created for young children contained phthalates.

Unfortunately, phthalates are hormone disrupting chemicals that have been linked to increased risk for breast cancer, as well as other diseases. And although Congress recognized that these substances needed to be banned from toys and other children’s products, the ban only took effect in February 2009, so most older pliable plastic toys may contain these chemicals.

Because young children may be particularly susceptible to the detrimental effects of endocrine disrupting chemicals, and especially since infants and toddlers place so many of their toys in their mouths (warm liquids, including saliva will increase leakage of the chemicals), it is important to be sure that your young children have phthalate-free toys, teethers and other products. Older toys, including those bought at yard sales or thrift chops, may well contain phthalates, as will any you have bought before this spring. Finances are tight, but a couple of newer, phthalate-free toys and teethers will be worth the money in the long run.

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Be Wary of Dry Cleaning Chemicals

Studies on Cape Cod have indicated that women who have been exposed to perchloroethylene (also called PCE or PERC – pronounced "perk") through their water sources, have an increased risk for breast cancer (pdf). PERC is the most common chemical used at dry cleaning shops. It accumulates in our body fat and may therefore remain in our bodies for long periods of time. In addition to long-term effects on health, including cancer, shorter term exposures to air-borne PERC can skin irritation, as well as dizziness and headaches.

To decrease your exposure to PERC, try to buy clothes that don't require dry cleaning. Before buying clothes that may need dry-cleaning, find out more about the material from which the items are made, and see if dry-cleaning is really necessary. Manufacturers often put this on the label to prevent liability because they must accept the return if a garment shrinks or loses its shape. Gentle wet washing (even in cold water) and air drying may be sufficient to counter problems of shrinkage or damage.

If you are using a dry-cleaner, find out what kind of solvents they use. If they use PERC, try to find a cleaner that uses a different process such as wet-cleaning, liquid CO2, or silicone. Note however, that there is considerable controversy over how much safer some of the alternative process really are.

If you get your clothes dry cleaned with PERC or other organic substances, be sure to remove the plastic packaging from your clothes and air them out, preferably outside of your home. Also, many fabrics that say, "dry clean only" don't require it.

Also avoid spot removers or carpet cleaners that contain PCE.

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Use Nontoxic Cleaning Supplies

Many household cleaning products contain chemicals that may be detrimental to our health. Just look at the labels: Many say "use in ventilated area", or "seek medical help if ingested", or "skin or eye irritant", etc. Unfortunately, there is very little regulatory oversight of cleaning products and many are very poorly labeled, with phrases like "secret formula" being used to tantalize the consumer into thinking there is special magic in the cleanser. In reality, many household cleaning products contain chemicals like alkylphenols (example: 4-nonylphenol) that are endocrine disruptors (endocrine disrupting chemicals mimic hormones and have been implicated in increased risk for breast cancer and other health problems) as well as toxins that affect both our brains and our reproductive systems.

For many household tasks, simple baking soda (a gentle abrasive) or dilute warm vinegar work as well if not better than more toxic alternatives. For other suggestions see these guides at the Environmental Risks and Breast Cancer project and The Daily Green.

Cook With Stainless Steel

Like cadmium, aluminum is a metal that mimics estrogen. In addition, laboratory studies have shown that aluminum can cause direct damage to DNA in several biological systems. Although studies have not shown a direct causal link between aluminum and breast cancer risk (little work has been reported in this area), breast tissue has been shown to concentrate aluminum and it is found in highest levels in the quadrant of the breast near the underarm region, the same area where the highest proportion of breast cancers are originally diagnosed.

Use alternatives to cooking utensils made out of aluminum, especially those that are older. Instead use pots or pans made out of stainless steel or cast iron. Newer anodized aluminum pots and pans are considerably safer than older, non-anodized forms as the process of anodizing prevents the aluminum from leaching into food as it is being cooked.

One other possible source of aluminum in breast tissue may be use of underarm antiperspirants. Try to avoid using underarm cosmetics that contain aluminum. Check for safer alternatives at the Environmental Working Group’s Safe Cosmetics database or use home-made solutions like diluted baking soda.

Find a natural deodorant that really works.