Phthalates–why you should care about these plastic additives

Aside from cost, aesthetics, and functionality, materials selection is now a topic priority for many consumers when they make a purchase. Consumers are becoming more aware of their choices for sustainable and reusable materials—even the potential health risks/toxicity associated with materials.

This is especially true for products containing plastics, particularly the additives used to make these plastics.

Phthalates are a class of man-made chemicals that have been widely used by the chemical industry to manufacture polymers. With more than 12 billion pounds of phthalates produced annually worldwide, they are the most commonly used plasticizers [1, 2]. These chemical additives can be found in a variety of for consumer products including construction materials, medical supplies, automotive parts, clothing, toys, and furniture.

Phthalates such as di(2-ethylhexyl) phthalate (DEHP), diisodecyl phthalate (DIDP), or diisononyl phthalate (DINP) are used as plasticizers to add flexibility and durability to polymers such as polyvinyl chloride (PVC). More importantly, they have excellent compatibility with a given polymer, low volatility, are water resistant, and inexpensive—all desirable properties of plasticizers [2].

The concern with using phthalates is that they could leach out from the polymer during usage because phthalates are not chemically bound to the polymers. They simply form secondary bonds to polymer chains—reducing polymer-polymer chain secondary bonding. This type of bonding provides more mobility overall for the polymer chains, resulting in a softer and more easily deformable polymers.

With the ubiquitous nature of phthalates, we are likely exposed to these compounds daily. Initially phthalates were reported to benign to humans in 2003 [3]. However a recent book by researchers Dr. John Meeker and Ms. Kelly Ferguson, from the University of Michigan School of Public Health in Michigan, USA, reviewed a number of studies conducted since 2003 that suspected phthalates may act as endocrine disrupting compounds that could lead to adverse reproductive development effects in humans [4].

Meeker and Ferguson concluded that the data on phthalates suggest exposure is associated with altered endocrine function, reproductive or developmental effects, possibly even asthma and allergy symptoms. However, it’s important to keep in mind that the authors believe further research is needed in order to determine whether there is a causal relationship between the exposure to phthalates and adverse health outcomes. They concluded that the human studies to date have been limited and the quantity and quality of data available varies—due to small study sizes, exposure levels/sources, multiple or competing physiological mechanisms—to name a few reasons.

While further toxicology studies may not sound very reassuring to the general public; chemical and materials science engineers have also been addressing the toxicity issue of phathalates by researching environmentally-benign plasticizers and/or chemically modifying plasticized polymers to reduce leaching.

As an alternative to phthalate, the Ohio Soybean Council and Battelle developed a new plasticizer made from modified soybean oil [2]. They found it to be fully compatible with PVC, and provides even higher thermal stability than other synthetic plasticizers such as DEHP [2]. Modified soybean oil is just one alternative to phthalate plasticizers. Other non-phthalate plasticizers include citrates, found in plastics used for food containers and phosphates, found in flame retardant electrical wire insulation.

As for government policies, the U.S. Consumer Product Safety passed a law in 2008 declaring children’s toys or child care products must contain less than 0.1% DEHP, dibutyl phthalate (DBP), or benzyl butyl phthalate (BBP) [5]. However, no other consumer products were given restrictions on phthalate concentrations.

Photo credit: Rachel Hoefling

So I’m not suggesting you throw out your shower curtain or retile your kitchen floor immediately. I’m pretty sure my garden hose is made using PVC with phthalate plasticizers. I’m simply saying it’s a good idea to keep yourself informed about your materials choices. There’s more than meets the eye when it comes to buying anything—not just choosing between black or white.

[1] Saravanabhavan, G., & Murray, J. (2012). Human Biological Monitoring of Diisononyl Phthalate and Diisodecyl Phthalate: A Review Journal of Environmental and Public Health, 2012, 1-11 DOI: 10.1155/2012/810501

[2] RAHMAN, M., & BRAZEL, C. (2004). The plasticizer market: an assessment of traditional plasticizers and research trends to meet new challenges Progress in Polymer Science, 29 (12), 1223-1248 DOI: 10.1016/j.progpolymsci.2004.10.001

[3] Phthalate Information Center, American Chemistry Council,
Inc., 2003

[4] Meeker, J. D. and Ferguson, K. K. (2012) Phthalates: Human Exposure and Related Health Effects, in Dioxins and Health: Including Other Persistent Organic Pollutants and Endocrine Disruptors, Third Edition (ed A. Schecter), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9781118184141.ch13

[5] Consumer Product Safety Improvement Act of 2008 §108, 15 U.S.C. § 2057c. (2008).
Name of Act § Section number, Volume number U.S.C. § Section number (Year).


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