People who want to avoid certain chemicals often spend extra time reading labels on cosmetics, baby products and household cleaners.
New research suggests that even careful shoppers may not always be able to tell what chemicals are actually present in the products they buy.
Scientists tested 113 everyday products and found unlisted chemicals in 98% of them. In some cases, laboratory results also appeared to contradict claims printed on packages or advertised by manufacturers.
The study was published in Environment & Health. It was led by researchers including senior author Jenna Hua, founder of the Million Marker Research Institute.
The products came from 12 categories and included items such as sunscreen, shampoo, soap and baby lotion. Researchers examined finished products rather than simply reviewing the ingredient information provided by manufacturers.
On average, a label named only 16 ingredients. Laboratory analysis, however, detected an average of 51 chemicals in each product, more than three times as many.
Not every unlisted chemical is necessarily harmful or intentionally added. Finished products can contain tiny amounts of substances that come from raw materials, manufacturing, packaging or chemical changes that happen during storage.
Even so, the researchers found that 85% of the products contained at least one unlisted chemical considered to have a known or suspected health hazard. These included substances from several chemical groups that scientists have been studying for years.
Among them were phthalates and parabens, some of which can affect the body’s hormone system. The researchers also detected fragrance chemicals, silicone-related contaminants and BHT, a chemical used in some products to slow deterioration.
Research has connected some chemicals in these groups with health concerns including reproductive problems, allergies and changes in development or metabolism. Certain substances have also been investigated for possible links to cancer.
Those associations need careful interpretation. A chemical can have hazardous properties at one level of exposure without necessarily causing harm at the much smaller amount found in a consumer product.
One of the most striking parts of the study involved marketing claims. More than one in four products contained a chemical that appeared inconsistent with information on the label or company website.
For example, researchers reported finding phthalates in some products labeled as free of phthalates. Some products promoted as 100% natural contained synthetic chemicals, while products making other “free-from” claims sometimes contained the substances they said were absent.
Products labeled hypoallergenic were not always free of substances associated with allergies or skin sensitivity. That could be particularly important for people who choose these products because they have sensitive skin or are trying to avoid a known trigger.
The researchers stressed that these findings do not prove companies deliberately added hidden chemicals. Contamination can occur at many points before a product reaches a bathroom shelf.
A raw ingredient may already contain an impurity, or a chemical may be introduced by factory equipment. Packaging can sometimes release substances, and ingredients may also react with one another or break down over time.
To look for these unexpected substances, the team used a method known as nontargeted analysis. In simple terms, instead of asking a laboratory to look only for several named chemicals, the method scans broadly for many chemical signals that researchers may not have predicted beforehand.
The scientists detected 3,141 signals and were able to identify 303 chemicals with confirmed, probable or tentative confidence. This broad approach can reveal substances that ordinary ingredient-based safety reviews might overlook.
Many consumer databases and certification systems judge products largely from their declared ingredients. The new study suggests those systems may provide an incomplete picture when contaminants, impurities or breakdown products are present but never appear on the label.
The authors want broader testing of finished, packaged products to become a routine part of safety and quality control. Such testing could sit alongside existing checks for bacteria, preservatives and whether a product remains stable during storage.
The study arrives as U.S. cosmetic regulation is changing. A 2022 law expanded the Food and Drug Administration’s authority, but companies generally are not required to conduct routine broad chemical screening for every unexpected contaminant in finished products.
The research has clear limitations. It shows that chemicals were detected, but it does not establish that consumers using these products receive doses high enough to cause the diseases associated with those substances.
The researchers also have not yet publicly identified the individual products in the study, saying specific brands and items will be detailed in a future report. That means consumers cannot use this paper alone to determine whether a particular bottle in their home was tested.
The strongest message is therefore about transparency and testing rather than panic. Ingredient labels remain useful, but direct analysis of finished products could reveal contamination that labels cannot and help make claims such as “phthalate-free” more dependable.
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Source: Million Marker Research Institute.
