'Troubling' levels of cancer-causing chemical found in more dry shampoo products, report alleges

High levels of benzene, a cancer-causing chemical, have been detected in more brands and batches of dry shampoo products, according to a new report from Valisure, an independent laboratory.

Just last month, certain aerosol dry shampoos -- including some Dove, Nexxus, Suave, TIGI and TRESemmé products -- were voluntarily recalled because of the potential presence of benzene.

Then on Monday, Valisure sent a citizen petition to the US Food and Drug Administration in which the lab described that among 148 batches from 34 different brands of dry shampoo products, 70% of samples tested showed "quantifiable" levels of benzene.

See full list of products listed in the petition here.

According to their report, 11 samples showed levels over 10 times more than 2 parts per million (ppm), the FDA limit for drugs.

RELATED: 19 dry shampoos recalled over potential cancer-causing ingredient

"However, the dry shampoos tested are not drugs and contain no active pharmaceutical ingredient for therapeutic purpose; therefore, any significant detection of benzene could be deemed unacceptable. Furthermore, Valisure shows data from the analysis of benzene by directly sampling contaminated air after spraying dry shampoo products, which suggests potential for short- and long-term inhalation exposure to high levels of benzene. The presence of this known human carcinogen in dry shampoo products that are regularly used indoors and in large volumes makes this finding especially troubling," David Light, Valisure's chief executive officer, and Qian Wu, Valisure's head of global analytics, wrote in the FDA Citizen Petition.

The petition urges the FDA to "expeditiously request recalls" on the affected batches of products containing benzene and better define limits for benzene contamination in other products.

The FDA normally takes 180 days to respond to a citizen petition.

In summary, three lots of dry shampoo products from one brand contained spray with more than 100 ppm of benzene, according to the petition, and some samples tested by Valisure showed more than 10 times the FDA drug limit. The petition also mentions that Valisure has detected benzene in other commonly used products as well, including certain hand sanitizers and sunscreens.

CNN contacted the brands listed in the petition and reached out to the FDA for comment but did not immediately hear back.

"The detection of high levels of benzene in dry shampoos should be cause for significant concern since these products are likely used indoors, where benzene may linger and be inhaled for prolonged periods of time," Light said in a news release Tuesday. "These and other issues identified by Valisure, including the detection of benzene in body spray, hand sanitizer, and sunscreen products, strongly underscore the importance of independent testing and its need to be better integrated into an increasingly complex and vulnerable global supply chain."

Last year, several deodorants and sunscreen products were recalled due to detections of benzene.

Benzene is formed from both natural and man-made processes. "Natural sources of benzene include volcanoes and forest fires. Benzene is also a natural part of crude oil, gasoline, and cigarette smoke," according to the US Centers for Disease Control and Prevention.

"The main way people are exposed is by breathing in air containing benzene," according the American Cancer Society.

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