The Lesser known Health Effects of Plastics

It has been 111 years since the first plastic 'bakelite' was synthesized in 1907 and took almost 50 years to become commercialized. Since then manufacturing industry boomed owing to its high strength to weight ratio. The race was on to create the most durable plastic that resisted degradation. Ironically, this very aspect became the Achilles heel for plastic biodegradability and its subsequent persistence in the environment. In 1997, Charles Moors discovered the Great Pacific Garbage Patch, a humongous cluster of plastic waste, which led to the awareness of plastic pollution. It until 2008, that the potential health hazards of plastics were identified by Saal and coworkers. What is more concerning that the issue was overlooked as late as 2015. Still we are at a point where we lack sufficient data long term toxicity damage that plastics cause.

Hazardous Plastics

Technically speaking, the intact plastic polymer itself is not toxic since its molecular weight is so high that it rarely passes through the gut in to the blood stream. However, environmental factors such as UV radiation, heat or abrasion can breakdown portions of the plastic polymer backbone into its constituent monomers. The resulting plastic monomers can leech and cause possible harm. Another major reason for toxicity is the additives such as plasticizers, stabilizers and flame retardants that are added to the plastic product. These additives are toxic because they are not chemically bound to the plastic polymer, thus are able to leech into its surrounding environment. Plastic monomers and additives are uptaken by the digestive system and enter the blood stream. Smaller sizes like microns and nano plastics are even able to enter the tissues. Other factors that influence uptake are charge and porosity of the plastic monomer. 

How Toxic are Different Types of Plastics?

Lithner and coworkers, devised a hazard ranking system for each type of plastic based on the relative toxicity of the constituent monomer. Which simply means that more toxic the monomer from which the plastic is made, higher it was placed in the hazard category. The most hazardous type of plastics that either caused cancer or cellular mutations included: 

• acrylates
• PVC: found in children toys, teethers and water pipes.
• styrene: found in food packaging.
• epoxy resins: found in glue and paints.
• polyurethane: used in furniture, bedding and carpet liners.

How do the Plastics react with the Human body?

Once these particles enter the cells they can cause disruptions of protein and fats constituents of the cell membrane. This causes the membrane to rupture and through this mechanism, can cause red blood cells to die off. Positively charged particles are thought to play a role in pulmonary toxicity as their charge allows them to be easily absorbed through the lungs. As mentioned earlier, plastic particles can enter the cells of the digestive system. If a sufficient quantity of these particles accumulates inside the cells it can lower cellular immunity, cause inflammation and oxidative damage. If the plastic is of such a nature that the body is unable to digest then, it may become permanently embedded in the tissue. Nevertheless, if somehow the plastic is eliminated through excretion or feces, their short term presence can still illicit chronic damage to organs like the brain and testicles.

Plastics and the Threat to Human Health

BPA was surprisingly manufactured as a synthetic estrogen but somehow made its way to the plastic industry. BPA can polymerize to form polycarbonate plastics and is currently used to manufacture plates, cutlery and in the lining of tin cans. BPA can easily leech through the plastic surface and contaminate foods, drinks and is considered highly toxic to humans. Once inside the body, the BPA molecule mimics estrogen and binds to steroid receptors. This activity exerts its effects on the urogenital system, bones, breasts, skin and hair. BPA can also cause thyroid hormone disruption, altered pancreatic function leading to diabetes and obesity and cardiovascular diseases. Infants are at the greatest risk of  BPA toxicity because a small dose can have a potent effect. BPA toxicity in infants causes reproductive and developmental defects such as cancers, neurological symptoms like autism and early maturation of young girls.
Phthalates a plastic additive can cause reproductive tract defects especially in newborn males, where the defects range from absence of epididymis, testicular lesions and delayed puberty. These defects either developed during gestation or during lactation. Phthalates can also cause premature breast development in adolescent girls
Epoxy resins can cause severe skin and lung irritation since it contains additives that can easily leech in to the skin and enter the airways too. Epichlorohydrin is an additive in epoxy resins and is a classified carcinogenic substance. The risk is even greater for those who are working in epoxy manufacturing plants.
Styrene can cause acute as well as chronic toxicity. Acute toxicity can lead to irritation of the eyes/mucous membranes and gastrointestinal dysfunction. Long term exposure can lead to chronic toxicity which is identified as headaches, fatigue, weakness, depression, hearing loss, and CNS malfunction. Research also indicates an occupational hazard for females working in styrene manufacturing industry in the form of abortions and reduced fertility. There is also gathering evidence that styrene exposure can lead to blood cancers.