The Right Chemistry: Ripped Jeans and Other Scientific Riddles

The Right Chemistry: Ripped Jeans and Other Scientific Riddles

I do not believe that jeans with traces of phthalates or yoga pants made with PFAS present a significant risk to the wearer. The problems are in its manufacture and disposal.

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Here is a question to ponder. When it comes to health, is it safer to wear ripped or unbroken jeans?

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Why does the question arise? It’s due to a study by Chinese and American researchers who investigated whether wearing clothes reduces exposure to phthalates, compounds that are of concern due to their potential carcinogenic and endocrine-disrupting effects. These chemicals are widely used to make plastics flexible, primarily polyvinyl chloride (PVC), but they also find uses as solvents and fixatives in perfumes. They are produced in large volume and can be detected in air, water and soil. Can phthalates migrate into the body through the skin, the researchers wondered?

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Subjects were asked to wear freshly washed jeans for one, five or 10 days. The bare parts of the body were rubbed, that is, the head and hands, as well as the legs that had been covered by the jeans. The swabs were then tested for phthalates. The expectation was that the fabric would reduce dermal exposure from air or dust. Although the levels of phthalates measured on body parts covered by clothing were lower, they were still significantly detectable. Additionally, phthalate levels in both the jeans and the legs increased over time. It appears that the fabric was absorbing phthalates from the environment and transferring them to the skin. But what do we do now with this information? Do we conclude that ripped jeans are a risk because they leave more parts of the body exposed? Should jeans be washed every time they are worn? Should we cover ourselves from head to toe to reduce exposure to phthalates?

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Hardly. The fact is that our ability to collect data has outpaced our ability to analyze what the data means. Do phthalate levels in skin wipes, measured in micrograms per square meter of skin, reflect absorption through the skin? Even if they do, is how much of any physiological consequence? How does this compare to phthalates that can be present in food due to contact with plastic pipes and containers?

In any case, the presence of a chemical substance cannot be equated with the presence of a risk.

Another complication is that there are many different phthalates with different toxicological profiles, and in addition to phthalates, we find numerous compounds, natural and synthetic, that can affect health under certain conditions. The only real conclusion here is that the ability of analytical chemists to detect trace amounts of substances is truly impressive and that industrial production of phthalates leads to indirect human exposure. The way to reduce such exposure is to reduce the production of these compounds.

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Although the anthem of toxicology is that “the dose makes the poison”, it is clear that sometimes that dose can be very small. No amount of lead is thought to be safe, and when it comes to potential endocrine disruptors like some phthalates, polyfluoroalkyl substances (PFAS) or nonylphenol ethoxylates (NPEs), even small amounts can have an effect, especially in babies. Certain commonly used azo dyes can release orthodianisidine, a carcinogenic amine. Although the ability of these amines to cause cancer is based on animal feeding studies and not on skin exposure, it is still preferable to avoid potential carcinogens.

While jeans don’t actually contain phthalates other than through adsorption from the environment, like many other fabrics, they can harbor other chemicals of concern, for example, the nonylphenol ethoxylates (NPEs) mentioned above that are widely used in textile production. These are effective surfactants, meaning they lower the surface tension of water, allowing it to spread more easily over a surface. Also, since one end of these molecules is attracted to water and the other end to oily substances, NPEs can remove dirt and prevent it from settling on a clean surface. Not surprisingly, NPEs are also widely used in various surface cleaners and laundry products.

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The production of textile and leather goods involves several stages of cleaning, dyeing and rinsing, all of which require the use of surfactants. Some of these remain on the garment and are released during washing. The main breakdown product of NPE is nonylphenol, a compound that has estrogen-like effects. When it ends up in waterways, nonylphenol can impact the growth and reproduction of aquatic life. Humans can be exposed by eating fish or shellfish, as well as through cleaning products, cosmetics, and fabrics. There is pressure on textile producers to reduce and eventually eliminate NPE.

Perhaps the chemicals of greatest concern in the apparel industry are Perfluoroalkyl Substances (PFAS) used for their stain and water resistant properties. They are often referred to as “forever chemicals” due to their persistence in the environment. There are thousands of PFASs out there, and some have been linked to reproductive problems, impaired immune systems, birth defects, thyroid disease, hormonal disorders, increased blood cholesterol, and even cancer. Although most of this evidence comes from high-dose animal or cell culture studies, the finding of PFAS in human blood is cause for concern. Some of this may come from exposure through clothing, but ingestion through food or water is a more likely source. Since PFAS are widely used in food packaging, cosmetics, non-stick pans, fire-fighting foam, stain-resistant upholstery, ski wax, and microchip production, it’s easy to see how some end up in the environment and, consequently, in our food and water.

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Where does all this leave us? I do not believe that jeans with traces of phthalates, yoga pants made with PFAS, or textiles processed with nonylphenolethoxylated surfactants pose a significant risk to the wearer. The problem is that the manufacturing of these items, as well as their eventual disposal, releases these chemicals into the environment from where they can come back and haunt us while polluting our air, food, and water.

Manufacturers and regulatory agencies must make an effort to reduce the use of compounds that have had a shadow of toxicity cast on them. Consumers can also play a role by buying fewer items. Do we really need to support the current “fast fashion” fad that is based on making fancy clothes so cheap that they are easily replaced and thrown away when the next trend is thrust upon us? Cheap usually means poor quality and careless use of processing chemicals, as bargain-priced products imported from China often demonstrate.

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Let’s go back to ripped jeans. Over-interpreting the jean study may lead to the conclusion that you can reduce your phthalate risk by patching rips. Frankly, though, I’ve never understood the appeal of giving in to this tattered fashion trend in the first place.

Joe Schwarcz is director of the Office of Science and Society at McGill University ( He hosts The Dr. Joe Show on CJAD Radio 800 AM every Sunday from 3-4 p.m.

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