Ingredient labels may not tell consumers everything that is inside their shampoo, sunscreen or baby lotion.
A new laboratory study found that almost every personal care and cleaning product tested contained at least one chemical that was not listed on its label.
Even more concerning, many products contained an unlisted chemical that researchers described as having a known or suspected health hazard.
Some products also contained substances that appeared to conflict directly with claims such as “phthalate-free,” “natural” or “hypoallergenic.”
The research was published in the journal Environment & Health. Senior author Jenna Hua is the founder of the Million Marker Research Institute, which studies environmental chemical exposures and their possible effects on health.
The researchers tested 113 products from 12 categories, including sunscreens, baby lotions, shampoos, soaps and household products. They wanted to compare what manufacturers listed on packages with what could actually be detected in the finished products.
The difference was large. A typical product listed about 16 ingredients on its label, while laboratory testing detected an average of 51 chemical substances.
Overall, 98% of the products contained at least one chemical that was not disclosed on the label. About 85% contained at least one unlisted substance with a known or suspected health concern, according to the researchers’ classification.
The team found several types of chemicals that have attracted scientific attention. These included phthalates, parabens, fragrance-related chemicals, silicone contaminants and the preservative or antioxidant BHT.
Some phthalates and parabens are known for their ability to interfere with hormone activity. Researchers have studied certain chemicals in these groups for possible links with reproductive problems, development, metabolism and some cancers.
However, detecting a potentially concerning chemical does not automatically mean a product is dangerous. Health risk depends on many factors, including the amount present, how often a person is exposed, whether the chemical can enter the body and how sensitive the individual is.
The study also found that marketing language did not reliably predict what was detected. Products described as “natural,” “nontoxic” or “organic” sometimes contained unlisted substances that have raised health concerns.
More than one-quarter of the tested products contained a chemical that appeared to contradict a claim made on the package or company website. Researchers reported finding phthalates in some products advertised as phthalate-free and synthetic chemicals in some products promoted as 100% natural.
Other products marketed as free of fragrance, parabens, silicones or oxybenzone contained those substances during laboratory testing. Some products described as hypoallergenic also contained chemicals known to cause allergic reactions or skin sensitivity in some people.
There are several possible explanations for these mismatches, and the study does not show that manufacturers deliberately hid ingredients. Chemicals can enter a product accidentally through raw materials, manufacturing equipment, packaging, storage or reactions that occur after ingredients are mixed.
A supplier can also change the composition of a raw material without an obvious change in the final ingredient list. Some detected chemicals may therefore be contaminants or breakdown products rather than substances intentionally added by the company.
To uncover these hidden chemicals, researchers used a broad testing method that searches for many substances at once instead of looking only for a short list of expected ingredients. The analysis produced 3,141 chemical signals and identified 303 compounds with different levels of certainty.
This approach matters because many safety systems begin with the ingredients a manufacturer declares. If a chemical is not on that list, traditional reviews may never investigate it even though consumers are still exposed to it in the finished product.
The researchers argue that finished products should be tested more directly. They recommend adding broad chemical screening to existing safety checks for issues such as bacteria, product stability and the effectiveness of preservatives.
The study also raises questions about U.S. regulation. The Modernization of Cosmetics Regulation Act of 2022 gave the Food and Drug Administration additional authority, but routine broad testing of finished cosmetics for unexpected chemical contaminants is generally not required.
The findings are important because they expose a weakness in relying entirely on labels, but they should not be interpreted as evidence that 85% of products will cause disease. The study focused on the presence of chemicals, not whether the detected amounts created harmful exposures in real-world use.
Another limitation is that the brands and individual products were not identified in the published information and are expected to appear in a later report. Independent testing and studies measuring actual exposure levels will be important for understanding how much risk, if any, specific products create.
Still, the research makes a strong case for checking what is actually in a finished bottle rather than assuming the ingredient list tells the complete story. Better testing could help manufacturers identify contamination earlier and give consumers more confidence that product claims match the contents.
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