Plastics

Plastics. These ubiquitous, revolutionary, modern phenomena have changed our lives in countless ways. However, in a day and age where we are increasingly aware of the toxicity of the world around us, plastics are constantly coming under scrutiny, and for good cause. This blog is meant to be a starting point on the safety profile of the various types of plastics and will hopefully encourage you to do more research and at least be conscious of plastics in your life.

The Number

Many of us already are aware that there are different number plastics. This is the little number that you look at on the bottom of the container to determine if you can recycle it depending on your region of the world. However, this number also has a big impact on the toxicity of the plastic. Here is a run-down on the numbers and what they mean:

#1- PETE- polyethylene terephthalate. This is the main plastic used in bottled beverages such as soda and water.

#2- HDPE- high density polyethylene. This plastic is harder and is used in detergent bottles and playground equipment.

#3- PVC- polyvinyl chloride. PVC is everywhere. It is used in pipes, housing siding, shower curtains, and many more.

#4- LDPE- low density polyethylene. This is the soft and pliable plastic used in plastic bags and trash bags.

#5- PP- polypropylene. This plastic is found in clothing (esp. thermal underwear), older tupperware, lab equipment, and automotive components.

#6- PS- polystyrene. This is the basis for styrofoam, disposable utensils, CD/DVD cases, bottle lids, etc.

#7- Other. This group includes fiberglass, nylon, and other plastics that don't fall into the above categories. This includes polycarbonates which can include the toxin so much in the news, BPA.

The Toxic Effect

Now that you know what that little number means, lets talk about the toxicity associated. Here is a quick overview of what the research shows in regards to the various types of plastics. Lets start with overall safety profile.

Safest plastics: #2, #4. These plastics have no detectable leeching capacity and have not been found in detectable amounts in humans.

Safer plastics: #1, #5. These plastics DO have the capacity to leech (increased risk with heating food/beverages in them). However, there is no detected health effects at this time.

Un-safe: #3, #6, some #7. These plastics are known to leech and have known adverse health effects.

Now, onto some of the specifics regarding some of these safety issues.

Polyethylene: #1, #2, #4. These are the most common plastics in use. There are no proven adverse health effects at this time. They are considered potential carcinogens, but there is no definitive data. The biggest concern with these plastics are more on the environment. The Great Pacific Garbage Patch, which is a plastic debris accumulation twice the size of Texas found in the Pacific ocean, is a famous example of plastic waste trapped by water currents. The majority of the plastic in these messes are polyethylene based and are a danger to sea life and the ocean ecology. You need only google this to see the horrific effects these plastics can have on sea life. My hat is off to California for banning plastic bags (polyethylene #4), but there is still a lot of work to be done worldwide to reduce the amount of these plastics getting into the environment.

Polyvinyl Chloride (PVC): #3.These plastics are commonly used in industry (piping, housing siding). However, they are also used in medical industry such as IV bags and tubing, often with the added chemicals such as DEHP or phthalates to soften and make them more pliable. Additionally, plasticizers such as DEHP are often used in food packaging which may pose a significant route of exposure4. PVC has been associated with increased risk of cardiovascular and nervous system effects1, DEHP has been associated with increased inflammatory markers including those specific for the liver and kidney2, and phthalates have been associated with development and exacerbation of allergies and asthma3. Most of the studies regarding these toxicities have been in people who work in processing plants making these products, so the exposure is far higher than most of us would experience in every day life. Still, it's worth consideration if these products are a big part of your life.

Polypropylene: #5. This plastic is commonly used for food storage such as yogurt containers, plastic storage tubs, and baby bottles. It is also used in thermal long underwear, disposable diapers, and surgical mesh. While there is no definitive evidence of direct health effects, studies have shown potential for leeching of chemicals into food, especially if the food is heated in the plastic container5.

Plasticizers: These are substances such as phthalates (which include DEHP, DBP, BBP, DINP, DIDP, DnOP) which were mentioned above and are commonly added to plastics for their softening effects to make the item more flexible. These chemicals are not chemically bonded to the plastic and tend to leech very easily. The biggest age group where we are concerned with exposure is in toddlers who are putting anything and everything into their mouth. Fortunately, plasticizers are not like some other environmental toxins (such as heavy metals) in that they do not bio-accumulate, meaning they are able to pass through the body and don't stick around and build up in crazy high amounts. However, exposure can be significant due to their ability to easily leech and they have been associated with reproductive and development issues in animal studies and are suspected to disrupt endocrine function (all those fabulous hormones) in humans5.  A correlation has also been noted between phthalate exposure and obesity6… just in case we needed another thing to blame our obesity crisis on! There is some hope with phthalates as the FDA in 2008 banned phthalates in any "children's toy or child care article or item that can be placed in a child's mouth" that contains more than 0.1% phthalate. Hey, at least it's a start!

Polystyrene: #6. This plastic is most famous for it's development into styrofoam, but is also used in plastic jewelry, CD/DVD cases, lab equipment, razors, etc. It is inexpensive, partially explaining it's widespread use. Unfortunately, this is one of the plastics that is commonly not accepted for recycling due to it's more extensive processing. One of the health effects that is associated with this plastic is the styrene monomers which can be released when these products are burned (along with many other unhealthy chemicals). Some of the primary symptoms associated with styrene toxicity are developmental, ototoxicity (damaging hearing), and impairment of color discrimination (figuring out which color that block is…)7, along with dizziness, fatigue, nausea/vomiting, cognitive loss, neural toxicity, and possible kidney and liver toxicity. More acute high exposures first affect the mucous membranes with respiratory irritation. Oral exposure has also been shown to inhibit iron absorption8. Although the amount of styrene you would need to be exposed to  for severe effects is enormous (500-1000mg/kg), there is still understandable concern about this plastic as a source of toxins.

Bisphenol A (BPA): This is the last of our topics today. BPA is a common additive to plastics and other resins. It is a component in polycarbonate beverage bottles and has also been used in metal can coatings. It has a long history of use in food packaging since the 1960s, but has recently been in the media as many countries have banned its used in food products as research shows that it is an endocrine disruptor (messes with those hormones, particularly estrogen)9.  BPA has also shown association with childhood lung function and wheeze10. While many think the US is behind the curve in banning BPA, they did ban use in baby bottles, sippy cups, and packaging for infant formula. Many companies are also voluntarily removing BPA from their products in response to consumer demand.

Well, I personally think that's plenty to mull over. Next time you pick up a plastic container, I hope you will look at the number and consider it beyond it's recycling capacity.

References:

1. Med Tr Prom Ekol. 2014;(4):24-9. Risk assessment of health disorders and quality of life in employees of modern polyvinyl chloride production. Meshchakova NM, D'iakovich MP, Shaiakhmetov SF, D'iakovich OA, Telezhkin VV.
2. Chemosphere. 2014 Jun 26;120C:37-44. doi: 10.1016/j.chemosphere.2014.05.053. [Epub ahead of print] Health hazard assessment of occupationally di-(2-ethylhexyl)-phthalate-exposed workers in China. Wang W, Xu X, Fan CQ

3. Ann Allergy Asthma Immunol. 2014 Jun;112(6):496-502. doi: 10.1016/j.anai.2014.03.013. Epub 2014 Apr 13. Effects of phthalates on the development and expression of allergic disease and asthma. North ML, Takaro TK, Diamond ML, Ellis AK.

4. Food Chem Toxicol. 2013 Jan;51:434-8. doi: 10.1016/j.fct.2012.10.015. Epub 2012 Oct 26. Di(2-ethylhexyl)phthalate (DEHP) and di-n-butylphthalate (DBP) exposure through diet in hospital patients. Cirillo T1, Fasano E, Esposito F, Montuori P, Amodio Cocchieri R.

5. Int J Hyg Environ Health. 2007 Oct;210(5):623-34. Epub 2007 Sep 21. Phthalates: toxicology and exposure. Heudorf U1, Mersch-Sundermann V, Angerer J.

6. Ann Pediatr Endocrinol Metab. 2014 Jun;19(2):69-75. doi: 10.6065/apem.2014.19.2.69. Epub 2014 Jun 30. Phthalate exposure and childhood obesity. Kim SH, Park MJ.

7. Food Chem Toxicol. 2014 Feb;64:258-69. doi: 10.1016/j.fct.2013.11.039. Epub 2013 Dec 4. Derivation of safe health-based exposure limits for potential consumer exposure to styrene migrating into food from food containers. Gelbke HP, Banton M, Faes E, Leibold E, Pemberton M, Duhayon S.

8. Nat Nanotechnol. 2012 Feb 12;7(4):264-71. doi: 10.1038/nnano.2012.3. Oral exposure to polystyrene nanoparticles affects iron absorption. Mahler GJ, Esch MB, Tako E, Southard TL, Archer SD, Glahn RP, Shuler ML

9. Reprod Toxicol. 2014 Sep 29. pii: S0890-6238(14)00249-4. doi: 10.1016/j.reprotox.2014.09.012. [Epub ahead of print] Estrogens in the wrong place at the wrong time: fetal BPA exposure and mammary cancer. Paulose T, Speroni L, Sonnenschein C, Soto AM.

10. JAMA Pediatr. 2014 Oct 6. doi: 10.1001/jamapediatrics.2014.1397. [Epub ahead of print] Bisphenol A Exposure and the Development of Wheeze and Lung Function in Children Through Age 5 Years. Spanier AJ, Kahn RS, Kunselman AR, Schaefer EW, Hornung R, Xu Y, Calafat AM, Lanphear BP.