March 10, 2021 – In this Big 3 Q&A, Russ Hauser, Frederick Lee Hisaw Professor of Reproductive Physiology and professor of environmental and occupational epidemiology, discusses a recent paper he co-authored with colleagues from Project TENDR (Targeting Environmental Neuro-Development Risks) that outlines the health dangers of chemicals called ortho-phthalates and calls for their elimination in consumer products.
Q: What are ortho-phthalates and where are they used?
A: These chemicals—generally referred to as “phthalates”—are a family of compounds that has been widely used for well over 50 years. They have many properties that make them useful in many different consumer products. One of their common uses is to soften vinyl plastic. Things like shower curtains, boots, and IV tubing are made from that same hard white plastic that a plumber would use, but when you add about 30% by weight to it of a specific phthalate, you get soft pliable vinyl plastic. Phthalates are also used in many personal care products such as colognes, perfumes, soaps, and shampoos, in the coatings of some medications, and in vinyl tubing used for food processing. I would estimate that phthalates are used in many hundreds if not thousands of different products.
One primary way that people can be exposed to phthalates is through diet. For example, it’s been shown that these chemicals can leach into food from vinyl plastic equipment and materials, food preparation gloves, and food packaging materials. Phthalates can also migrate into indoor air and household dust from products like vinyl flooring and wall coverings. Numerous studies have found links between personal care product use and concentrations of phthalate metabolites in urine. And phthalates are transferred from mother to fetus during pregnancy.
Q: Can you describe some of the health impacts of these chemicals?
A: Phthalates have been very well studied in animal models. They’ve been shown to be anti-androgenic—in other words, they decrease testosterone. In studies with rats, it’s been shown that if you dose the pregnant mother, the offspring have defects of the male reproductive tract. There have also been studies in humans that have found anti-androgenic effects on development of the male reproductive tract.
In the last ten years, epidemiologic studies have also shown that prenatal exposure to phthalates affects children’s neurodevelopmental and neurobehavioral outcomes. That was the focus of the new paper, which reviewed more than a dozen studies that have shown that maternal exposure to ortho-phthalates during pregnancy can impair child brain development and increase children’s risks for learning, attention, and behavioral disorders.
Q: What has been done so far in the U.S. to reduce the use of ortho-phthalates, and what more should be done?
A: In 2017, the Consumer Product Safety Commission banned the use of eight ortho-phthalates in children’s toys and child-care articles. But in terms of their use in vinyl plastics and personal care products, there’s currently no specific legislation by other governmental agencies. Manufacturer’s decisions to reduce or eliminate the use of phthalates in these other products is largely voluntary. Thus there’s still a long way to go.
For some products, it’s very doable to eliminate the use of ortho-phthalates. For example, there are other chemicals that you can use as plasticizers to soften vinyl plastic, and manufacturers have already made substitutions in some products. However, we do need to study what they’re using for substitute chemicals—whether they’re using other compounds that may also carry risks.
With personal care products, there are other chemicals that can be used besides phthalates. For instance, nail polish frequently contained one of the phthalates called dibutyl phthalate (DBP)—it kept nail polish from being brittle—and now there are formulations that don’t contain DBP.
I think the goal of phthalate elimination from consumer products is achievable. Part of the reason we’re pushing for elimination is that it’s very hard for consumers to know what products ortho-phthalates are in—especially personal care products. If phthalates in the product are considered part of the scent formulation, they don’t need to be listed on the ingredient list, because scents are considered proprietary. Even though some products do list phthalates, it’s really hard for consumers to read the labels with these long chemical names. It’s really hard for even a very knowledgeable consumer to buy products and avoid phthalates.