A brief summary of major studies is as follows:
Published in 2003 in the European Journal of Cancer Prevention, interviewed 437 women with breast cancer about their past and present use of deodorants. The study reported that women who applied deodorant at least twice a week and shaved their armpits at least three times a week developed breast cancer almost 15 years younger than women who did neither. Neither shaving nor applying a deodorant alone was linked with a younger age of diagnosis of the disease. The study’s methodology has been criticized by industry researchers as it did not interview non-breast cancer deodorant users or account for the age of the women being interviewed.
The World Health Organization has linked exposure to aluminum to Alzheimer’s disease, with higher frequencies of deodorant use corresponding to higher risks of developing Alzheimer’s. Abnormal accumulation of aluminum has been found in the brains of people with Alzheimer’s disease, and when aluminum is injected into the brains of laboratory animals, the animals develop a neurological disease similar to Alzheimer’s.
Another study published in 2004 in the Journal of Applied Toxicology, looked at the synthetic chemicals, parabens. The researchers looked at 20 human breast tumor samples and found that parabens were present in 18 of them. They concluded that these results suggested that parabens in deodorants could be absorbed through the skin and increase the risk of breast cancer. Again, many experts have raised concerns about the conclusions of this study. For example, the study was very small, it did not look at the level of parabens in breast tissue of women without breast cancer, nor did it establish that the parabens actually came from deodorants or that they were absorbed through the armpits.
At the moment, all the study has shown is that the body can absorb parabens and that these chemicals are found in some breast cancer tissue. It does not show that parabens can increase the risk of or cause breast cancer.
The main conflicting research results from a epidemiologic study published in 2002 that compared 813 women with breast cancer and 793 women without the disease. The researchers found no link between breast cancer risk and antiperspirant use, deodorant use, or underarm shaving