Long-term low-level expo-sure to minute amounts of the heavy metal cadmium, found in our air, food and water, and also in many everyday cosmetics, can stimulate breast cancer, and also cause it to become increasingly more aggressive, according to new California research.
Recent studies from the Dominican University of California have shown that exposure to cadmium over prolonged periods of time causes breast cancer cells to become increasingly more aggressive and malignant.
Cells chronically exposed to cadmium express higher levels of a protein called SDF-1, which is associated with invasive tumours and the spread of cancer by passage through the outer tissue barrier of the breast.
This latest evidence bolsters earlier evidence showing that cadmium plays a significant role in the development of breast cancer. Nevertheless, this is the first major research showing that effects occur with chronic low-level exposure.
Breast cancer results when epithelial cells in the breast grow abnormally, often when cell growth is changed by circulating levels of estrogen and then stimulated by breast estrogen receptors. Cadmium acts as an endocrine disruptor by mimicking estrogen and disrupting normal estrogen pathways.
As yet, the California researchers do not understand cadmium's precise role. "We are trying to figure out if it is the cadmium causing cancer or the cancer attracting the cadmi-um," said Maggie Louie, associate professor of biochemistry, the study's author, who presented her findings at the American Society for Biochemis-try and Molecular Biology's 2012 Annual Meeting in San Diego.
In Louie's study, breast cancer cells with prolonged exposure to cadmium demonstrated an increased ability to migrate through the outer barrier of breast tissue-a classical sign of a cancer cell's ability to spread.
The worry, according to Louie, is that we are bombarded by minute levels of the heavy metal on a daily basis. "Our research shows that even small concentrations of this metal at prolonged exposures can cause breast cancer cell growth."
The heavy metal, produced as a byproduct of mining and refining zinc, lead and copper ore, makes its way into our water, air and food supplies. It is found in the rocks that are mined to produce phosphate fertilizers, and is also found in rechargeable batteries and cigarette smoke. Cadmium emission levels in the atmosphere have soared because products containing the metal are simply disposed of as household waste, rather than being recycled (Br Med Bull, 2003; 68: 167-82).
The face of toxicity
Inhaling cigarette smoke and passive smoking are one primary source of cadmium, but another chronic source of exposure is cosmetics. Many major brands of cosmetics contain a cocktail of toxic heavy metals, including cadmium, according to recent laboratory analyses.
A recent international report on branded cosmetics by the Ontario-based environmental organization Environmental Defence examined 49 popular makeup products, and discovered the presence of cadmium in a little over half the products tested, which included foundations, powders, concealers, bronzers, eyeliners, eye shadows, lip glosses and lipsticks.
Those with the highest levels of cadmium included NYX Mega Shine Lip Gloss, Cover Girl Perfect Point Plus Eyeliner and Cover Girl Ultimate Finish Liquid Powder Makeup. Clinique Stay True Foundation, Laura Mercier Secret Camouflage and L'Or'eal Bare Naturale Mascara were also found to contain cadmium. Seven of the eight heavy metals tested for were found in virtually all of the 49 popular products save one: Annabelle Mineral Pigment Dust (Solar).
These results are worrying, considering the amount of makeup the average woman slaps on her face. According to a 2004 report by the US-based Environmental Working Group (EWG), the average woman applies around 12 makeup products per day that contain, on aggregate, 168 unique ingredients. What this adds up to is that one in 13 women is being exposed to substances that are confirmed or probable carcinogens. Furthermore, the EWG discovered that at least 146 cosmetics ingredients include impurities, such as cadmium, that are linked to cancer.
Although all of the heavy metals in the Environmental Defence report have damaging effects, those of most concern are cadmium, arsenic and lead. Authorities such as the US Food and Drug Administration (FDA) have long considered cadmium to be toxic, and its adverse health effects have long been recognized. Indeed, Canada and Europe have banned cadmium as an intentional ingredient in cosmetics.
Nevertheless, as in the US, the heavy metal is not banned as a product 'impurity' if it is present inadvertently as a contaminant of raw ingredients, or formed as a byproduct during the manufacturing process and breakdown of certain ingredients. As cadmium and other heavy metals are naturally present in the soil, in rocks and in many pigments and other raw materials that go into cosmetics, its inclusion in the final manufactured product is considered unavoidable. Canada, but not the US, has set 'draft limits'-or upper allowable levels-for impurities like cadmium. None of the products tested by Environmental Defence-including those with the highest levels-exceeded Canada's upper limit.
The Campaign for Safe Cosmetics, for one, has called for major cosmetics firms to come clean-to make product labelling more transparent, particularly about heavy metals, and to eventually reformulate their products.
Other worrying findings
Louie's research on cumulative exposures to cadmium has other repercussions. New research shows that women who eat copious amounts of bread, potatoes and root vegetables also increase their risk of breast cancer by nearly 30 per cent, largely because these foods are most likely to contain cadmium from their fertilizers.
Cereals and root vegetables such as turnips, parsnips and carrots, which are grown in the ground, retain the highest levels. Swedish researchers, who studied the diets and health of more than 55,000 women over a 12-year period, discovered that the risk was highest in women of normal weight presumably because, in their case, the cadmium present was affecting a greater percentage of their body (Cancer Res, 2012; 72: 1459-66).
This research, combined with Louie's, suggests that women consuming these foods and using makeup regularly are facing considerable breast-cancer risks.
Besides cancer, cadmium has also been linked to osteoporosis. Studies have shown that long-term exposure to even low levels of cadmium can decrease bone density and increase the risk of fractures, and also lead to a loss in height. In one Belgian study, women who had double the normal level of cadmium in their urine increased their risk of fracture by 73 per cent, while men with the same cadmium levels had a 60-per-cent higher risk. As with the breast cancer study, this research shows that the damage is caused by long-term exposures to even low levels (Lancet, 1999; 353: 1140-4).
Chronic low-level exposure to cadmium has also been linked to depression, kidney disease, high blood pressure, liver disease, and nerve and brain damage.
Factfile: How to avoid exposure
- Quit smoking. Cigarettes are probably the biggest source of cadmium exposure.
- Use 'eco-friendly' and 'organic' cosmetics. Try brands such as Dr Hauschka, Aveda, Aubrey Organics and Neways. Many 'natural' cosmetics are not entirely free of chemicals, but at least contain far fewer nasties.
- Wear makeup judiciously. Think twice about how much makeup you need every day and whether all of it is necessary.
- Eat an organic, well-balanced diet. Cadmium is more likely to cause harm when your body is low in essential nutrients such as zinc, iron, copper, calcium and amino acids (J Environ Qual, 1988; 17: 175-80).
- Avoid foods known to be high-risk. These include non-organic bread, potatoes, root vegetables, and any fruits and vegetables sprayed with pesticides or grown in soil with fertilizers.
- Steer clear of coastal and inland freshwater seafood (fish, shellfish and deepwater fish such as swordfish and tuna). These are known to contain heavy metals, including cadmium.
- Detox. Take detoxifying supplements, including vitamins A, B-complex and C, selenium and zinc.
- Take heavy-metal detoxifiers. NAC (N-acetylcysteine), a form of the amino-acid l-cysteine, and MSM (methylsulphonylmethane) have both been shown to remove cadmium from the bloodstream, at least in experimental animals (Biol Trace Elem Res, 2000; 76: 19-30).
- Add spirulina to your diet. This freshwater blue-green algae has a long history of use as a heavy-metal detoxifier.