A new study from Canada shows that preservatives commonly used in cosmetics, lotions, and shampoos can be found in the urine and breast milk of pregnant women.
The article, published in the April 4th issue of Environmental Science and Technology, looked at the relationship between how often pregnant women used personal care products and the levels of preservatives, specifically parabens, present in their urine and breast milk. The women in the study noted the cosmetics they used on a daily basis and researchers calculated if parabens levels were related to the number of personal care products used.
Scientists from Health Canada, Brown University, Harvard University, and the Ottawa Hospital Research Institute analyzed urine samples from 80 women from 2009-2010. All samples were collected during the second and third trimesters and breast milk samples were collected from 2-3 months post-partum. Women were asked to indicate the number and type of personal care products they used each day in a diary. Products were separated into categories such as deodorants, make-up, shampoos, conditioners, body lotions, hand soaps, and lip products. Four different types of parabens were measured by chemical analysis: butylparaben, methylparaben, n-propylparaben, and ethyl paraben.
Parabens are used in cosmetics and other personal care products, including soaps and shampoos, as an anti-microbial preservative. Previous studies showed that parabens can be found in over 40% of rinse-off products (shampoos and conditioners, body wash, and face cleaners). Parabens are also found in leave-on cosmetics such as lotions and lipsticks, with methylparaben being the most abundant. Recent studies showed that some parabens can act as weak estrogen mimics. This finding, coupled with a 2004 study that found parabens in the breast tissues of women with breast cancer, raised concern about their ability to cause cancer. After scientific review, parabens are still considered safe for use in personal care products by the FDA, but certain types of parabens have been banned in the EU.
The study showed that methylparaben was the most prevalent paraben in both urine and breast milk samples. Methylparaben levels in breast milk were 30 times lower than levels in urine samples. On average, the highest levels of parabens were found in urine samples collected during the morning hours (from 8am until noon) with the lowest levels seen in the evening (from 6pm to midnight). The researchers believe that this is due to women using more cosmetics and personal care products in the morning hours.
Researchers also compared paraben levels in urine between women who used different amounts of personal care products. Women were classified as low users (0-5 products in a 24 hour period), medium users (6-9 products), or high users (10-14 products). When comparing different types of users, medium users had 21% higher levels of methylparaben in their urine when compared to low users, and high users had 161% more methylparaben than low users.
The researchers also found much higher parabens levels when comparing women who did not report using a specific product versus those who did report using a product. For example, women who reported using lotion had 99% more methylparaben in their urine than women who did not use lotion. However, some products, such as oral care products, led to variable paraben levels that did not clearly show an increase with increased usage. This could be due to study participants forgetting to log certain items or differences in how the women used each product.
Paraben levels measured in breast milk did not demonstrate a clear connection to personal care product use. Further analysis showed an increase in methylparaben levels in breast milk in women that reported using eye make-up. However, the magnitude of increase is small, strongly varies between study participants, and is found in only a small subset of the study group.
Paraben levels in urine samples are lower than what was reported in other studies from the US, Spain, and Puerto Rico. This may be due to differences in the types and amounts of personal care product used among different socioeconomic groups. Other studies also found that women are more likely to have higher urinary paraben levels than men, which the researchers believe is due to women using more personal care products.
Parabens are 10,000 times less potent than natural estrogen. Parabens are also far less estrogenic than natural phytoestrogens like daidzein, which is found in soy. Epidemiologists have yet to find any associated cancer risks linked to phytoestrogen consumption, so the chance that an estrogen as weak as parabens will cause harm is extremely unlikely.
Critics of the 2004 breast cancer study which reported that parabens were present in breast cancer tissue point out several flaws with the findings. Researchers did not measure paraben levels in non-cancerous tissues, making it impossible to assign any blame to parabens in causing breast cancer. Parabens also have a very short half-life, which means that these chemicals do not remain in the body for very long and are rapidly excreted.
Concerns about paraben safety led many cosmetics companies and consumers to seek out paraben-free alternatives. Regulators are still working to ensure that parabens are safe for consumer use but the data available now seem to point to parabens being of little concern.