Can you boil plastic? (3 Helpful Points)

In this brief guide, we will answer the question, can you boil plastic? We will discuss if you should boil plastic and some risks associated with carrying out such a practice. We will highlight some ways to use plastic in the safest way possible. 

Can you boil plastic?

Plastic packaging is the largest end-use market segment accounting for almost 40% of the total worldwide plastic usage. Over 500 billion plastic bags are used worldwide annually, and the average working life of a plastic bag is 15 min (1).

You cannot boil plastic because it can make it unsafe. No kind of plastic is safe enough to be boiled. Boiling, heating, and even scratching can make plastic unsafe. 

According to the USDA, sometimes meat or poultry is accidentally cooked with some of the packaging materials. For example: giblets cooked inside the turkey in their packaging; a beef roast cooked with the absorbent pad from the fresh meat packaging underneath; or a ham with the plastic bone protector or brown paper left on. These packaging materials are clearly not intended to be cooked, however if this happens and the packaging materials remain unaltered (that is, do not melt or come apart) the cooked meat will not pose an imminent health hazard. If the packaging materials have melted or changed shape in some other way, do not use the product because harmful chemicals may have leached into the surrounding meat (2).

You cannot boil food in plastic either. A high temperature that exceeds even 149 Fahrenheits would make the plastic melt. However, some plastics are thermally stable and suitable for heating (3).

Exposing plastic to heat causes BPA compounds to leach out. Do not use plastic that you suspect contains BPA. BPA is related to many types of cancer that can be caused by prolonged exposure. BPA is known to cause changes in the function of human tissues (3).

If you expose plastic to the boiling temperature of the water, it will release BPA 55 times faster than it would otherwise (4). 

Never heat a plastic bag or container that has Polyvinyl Chloride (PVC) or polycarbonate plastic as a constituent. Bisphenol is a carcinogenic compound and has estrogen-mimicking properties. BPA has well characterized estrogenic and other endocrine disrupting activities that are mediated via multiple molecular mechanisms (4).

Polyethylene bags will start to melt at a lower temperature than boiling water that is 105–115° Celsius (5). However, both high and low density polyethylene bring no risk to health (3).

Polypropylene is a safe bet for food and beverage storage and can withstand high temperatures. You can expose polypropylene plastic to warmth but it is never a good idea to boil plastic. 

Polypropylene is considered to be the safest plastic of all. Propylene is heat resistant and does not leach chemicals as easily as other plastics. It should be noted here that no harmful substances are found in food or water from polypropylene plastic. Most polypropylene plastic is microwavable and washed with a dishwasher, but they do not cause any harm (3).

Plastics made for food are called thermoplastics. Thermoplastics are made by polymerizing a particular monomer, with aid from a catalyst that changes them to a high molecular weight chain.

The manufactured polymer is then mixed with the additives such as antioxidants, plasticizers, and clarifiers to form a resin.

Will plastic melt if you boil it?

Plastic does not melt readily, it has a higher melting point than water. Even though a plastic called polylactic acid starts to melt at around as low as 70 Celsius, depending on the composition and synthesis method (6). 

However, it is not a good idea to boil plastic. Even if plastic does not melt it can become unsafe for you and your family. 

When the temperature of Polyethylene exceeds 149 Fahrenheit, the substance starts to break down. As plastic softens, it releases its residues which can easily make their way into your food (2).

Most types of plastic will not melt in boiling water because it is not a high enough temperature to break the structure of plastic 

polyethylene (PE), polypropylene (PE), polyvinyl chloride are tough variants of plastic that are comparatively heat resistant (3). 

Why is plastic unsafe?

There are a number of factors that go into determining the harm or safety of heating plastic containers or bags. Different types of plastics are at varying levels of harm, depending on the kind of plastic used, the plasticizer added, the temperature and duration at which the container was heated. Plastics contain many chemical and hazardous substances such as Bisphenol A (BPA), phthalates, antiminitroxide, brominated flame retardants, and poly- fluorinated chemicals etc. which are a serious risk factor for human health and environment (3).

Moreover, the food that is heated also has a role to play when plastic is heated. Fatty foods are more vulnerable to taking up chemicals from their package. Migration of chemical substances is highly dependent upon processing and storage conditions, the nature of the packaging material, and the compounds it may contain, as well as the chemical properties of the food (7).

Plastics are made of materials that are not inert. When a substance is not inert, it can leach its chemicals and transfer them to another substance and contaminate it. 

Phthalates, acetyl tributyl citrate, and dioctyl adipate are known to be plasticizers. The plasticizers are added to plastics to give them a defined shape, keep them flexible and less brittle. If you boil or apply heat to plastics, these chemicals can leach out. 

If you want to boil food, it is best to use heat-resistant glass, ceramics, and stainless steel. It is best to follow instructions given by the food and drug administration authority and refrain from using packages other than their intended purpose. 

Phthalates are environmental contaminants that act as hormone disruptors in the human body. The phthalates exhibit hormone-like behavior and disrupt the endocrine system of the body. 

Subjecting to these chemicals can have adverse health outcomes, especially in young children. The chemical can interfere with the development of growth of children who are vulnerable to this chemical. 

Even if plastic is BPA-free, it can have estrogenic activity. Estrogen activity receptors can cause early puberty in females, reduced sperm count, and obesity (3). 

Estrogen activity is also known to cause altered sex-specific activity and reproductive function. Not to mention, the cause of most types of cancers including breast, ovarian, testicular, and prostate cancer lies in the use and abuse of the estrogen activity receptors (4). 

Conclusion

In this brief guide, we answered the question, can you boil plastic? We discussed if you should boil plastic and some risks associated with carrying out such a practice. We highlighted some ways to use plastic in the safest way possible. 

Citations

1. Kosior, Edward, and Jonathan Mitchell. Current industry position on plastic production and recycling. Plastic waste and recycling. Academic Press, 2020. 133-162.
2. Is it safe if meat was cooked with plastic wrapping left on it? Ask USDA. 2019.
3. Proshad, Ram, et al. Toxic effects of plastic on human health and environment: A consequences of health risk assessment in Bangladesh. Int J Health, 2018, 6, 1-5.
4. Le, Hoa H., et al. Bisphenol A is released from polycarbonate drinking bottles and mimics the neurotoxic actions of estrogen in developing cerebellar neurons. Toxicol lett, 2008, 176, 149-156.
5. Berk, Zeki. Food process engineering and technology. Academic press, 2018.
6. Hortos Llobera, Martí, Sebastian Espino, and Jordi Bou Serra. Influence of temperature on high molecular weight poly (lactic acid) stereocomplex formation. Express polym lett, 2019, 13, 123-134.
7. Bhunia, Kanishka, et al. Migration of chemical compounds from packaging polymers during microwave, conventional heat treatment, and storage. Comprehen Rev Food Sci Food Safe, 2013, 12, 523-545.