What is EDC leaching?

by Iris Kang

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Endocrine disrupting chemicals entered the world of food packaging through a different name - plasticizers. Plasticizers, like phthalates, were implemented into food packaging material for a favorable balance of several properties.

 

Zooming in and focusing on phthalates allows us to take a look at their chemical properties. The ester functional group of the ortho-phthalic acids allows phthalates to have high boiling point, good insulation, high tensile strength, and low brittle temperature (Wypych, 2017). The flexibility provided by these plasticizers allows the packaging to be used without as much tension from deformation. Furthermore, the chemical has the property of resisting water, which is a crucial component of food packaging to keep materials from getting soggy or melting due to the food inside (Vieira, et al., 2011).

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ortho-phthalic acid

ester functional group

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Epoxy resin is also another class of chemicals that is shown to be endocrine disrupting. However, these chemicals were obviously first used in food packaging for a different purpose. An example of an epoxy resin chemical with endocrine disrupting factors is Bisphenol A (BPA). BPA contains phenolic epoxy resins, which can be used to serve as a protective coating for food and drink containers. When using aluminum cans as food packaging, epoxy resin is often used as a coating to prevent the metal from rust and corrosion (Almeida, et al., 2018). Furthermore, BPA polymers serve as excellent thermal and mechanical barriers as the polymers are highly cross-linked (Dhuey, et al. 2022). On top of these structural and functional benefits of these chemicals, the plasticizers that are currently being used are simple and affordable. The cost-effectiveness of these chemicals make them perfect for use in large industries like the food packaging industry as it can lead to greater profit.

 

As seen above, plasticizers came into the food packaging industry with only positive intentions in mind. Their purpose was to make packaging more flexible, lighter, more resistant to heat, and more durable. However, with the implementation of plasticizers came the unforeseen side effect: endocrine disruption.

 

Endocrine disruption came to the surface when these chemicals were found to be leaching. Leaching means that these chemicals, which are supposed to stay in the outer packaging material, are seeping into the food inside and thus, being consumed by whoever eats the food. 

 

Plasticizer chemicals can leach into food through several ways. The first way is through the chemical breakdown of bonds that are holding the chemical particles together. When phthalates are used in combination with adipates, the chemicals interact with bonding that prevents the endocrine disrupting chemicals from also bonding to the polymer matrix (Duan, et al., 2020). Furthermore, chemicals themselves can break down from the oligomer form through food contact. In the exposure to heat or other substances in food, oligomers can deconstruct through hydrolysis or ethanolysis and migrate into food (Brenz, et al., 2020).

 

Another way that plasticizers can leach into food is through the chemical properties themselves. For example, many chemicals that are used as plasticizers are added for their water resisting characteristics. This allows the packaging to stay intact when food or liquid is stored. However, this property also often comes with a loophole: many of these water resistant chemicals are lipid-soluble. Thus, the lipid content in many of our food items can affect the solubility of chemicals such as the plasticizer di (2-ethylhexyl) phthalate (DEHP) (Erythropel, et al., 2014). When a chemical is soluble, that means the chemical mixes easily with the solvent. The exposure to these chemicals through food consumption can be detrimental to an individual’s health.

 

Chemicals like phthalates or BPA can be extremely beneficial in making packaging more effective. In fact, these chemicals do hold beneficial properties when in food packaging. However, when these chemicals leach into the food through chemical or physical interactions, these chemicals now become harmful endocrine disrupting chemicals. Leaching is an important concept to know when discussing endocrine disrupting chemicals in food packaging, because it allows us to recognize the transition between benefit and harm for plasticizers. It is crucial to recognize that these chemicals were not added to food packaging with harm intended, but through leaching harm was inflicted to consumers. Thus, the newfound knowledge of harm through plasticizers should prompt action to address the issue of endocrine disruption in food packaging.