Many massage therapists turn to natural and organic ingredients when choosing products, and new research supports that behavior. When it comes to household cleaning and personal-care products, natural could be better.

Researchers at the American Chemical Society found that household detergents and shampoos may form a harmful substance in wastewater, one that could contribute to cancer.

According to a press release from the society, “Scientists are reporting evidence that certain ingredients in shampoo, detergents and other household cleaning agents may be a source of precursor materials for formation of a suspected cancer-causing contaminant in water supplies that receive water from sewage treatment plants.”

The study sheds new light on possible environmental sources of this poorly understood water contaminant, called NDMA, which is of ongoing concern to health officials.

“Scientists have known that NDMA and other nitrosamines can form in small amounts during the disinfection of wastewater and water with chloramines,” release noted. “When mixed with chloramine, some household cleaning products, including shampoo, dishwashing detergent and laundry detergent, formed NDMA.

The report notes that sewage treatment plants may remove some of quaternary amines that form NDMA; however, quaternary amines are used in such large quantities that some still may persist and have a potentially harmful effect in the effluents from sewage treatment plants.