Expert: Angel Evangelista - 1/28/2009

Question
QUESTION: Hi, I'm a 3rd year Mass Communication student of Far Eastern University, Philippines. I'm doing an investigative report on the health hazards of drinking bottled water( if there are any).  I'm not really sure whether my questions fall under your expertise, but I do hope you can answer it. Thank you very much!

1. Is it true that PET bottles contain carcinogens? What are these substances?
2.When are these substances released?

ANSWER: Hi, I'm a 3rd year Mass Communication student of Far Eastern University, Philippines. I'm doing an investigative report on the health hazards of drinking bottled water( if there are any).  I'm not really sure whether my questions fall under your expertise, but I do hope you can answer it. Thank you very much!

1. Is it true that PET bottles contain carcinogens? What are these substances?
2.When are these substances released?


Answering this question might invite either your doubts or your scorn of the chemicals industry.  I am forced to answer this carefully, but always truthfully.  I am very well aware of the “chemical soup” we live in, more so because I have an expertise in chemistry, chemical engineering, and industrial plastics, chemicals, and petroleum processes.  Hence, much of what I write below comes from another post on this website that I answered.  Hope it helps.

PET, Polyethylene terephthalate, is like any commercial bulk plastic – the manufacture, extrusion, and end use are fairly similar for the most part.


The answer to your question is complicated by, surprisingly, a wide variety of laws and standards or lack of it, manufacturing techniques and processes, modifiers and additives to plastic to create desirable properties, and so on.  PET plastic made by one manufacturer can be quantitatively chemically different than the same PET made by another manufacturer.  In addition, most bulk plastics producers don’t actually fabricate and mold the bulk plastic they produce (on a massive scale) into finished consumer & retail products, like plastic bottles, spoons, forks, and toys, among other things.  Each finished plastic product destined for the retail and consumer market is in turn produced by a myriad of plastic mold, extrusion, and fabrication companies.

PET would at first seem to be simply a series of carbon and hydrogen atoms chemically bonded into a long string of identical molecules; that is, a polymer of the propylene molecule.  The bottom line is that PET in its most pure synthetic form would be simply carbon and hydrogen atoms.  If this were to burn or melt, you would get the following products – CO2 (carbon dioxide), CO (carbon Monoxide), H2O (water, in vapor form most likely), and C (carbon, as in a dark solid ash or soot).  PET is never produced in purely synthetic form.  It is never pure hydrogen and carbon atoms synthesized into a beautiful polymer.  Nothing is.  Achieving extremely pure concentrations of anything, even to 99.999% purity, is industrially impossible and economically unfeasible.

Hence, there will always be contaminants during the manufacture, handling, and transport of the bulk plastic, even some introduced with the raw materials.  The production process itself introduces a catalyst or reagent or “co-monomer” that itself will introduce some tiny impurities. But suffice it to say that the bulk manufacture introduces a tiny immeasurable amount of impurities, which could be anything.  (If this were recycled plastic, the impurities could be orders of magnitude more.  Hence, you will NEVER find a food-grade plastic product made from any recycled plastic material, unless some foreign country lacks any desire to regulate and enforce such a law, like one particular large Asian country not far from the Philippines that I won't name. By the way they just poisoned thousands of their own babies, which hopefully will teach them a lesson and the American Public as well.)

Next, PET is never molded into a finished consumer or retail product without some use of plasticizers, modifiers, and/or release or blow-mold agents.  Any of these compounds are present in any finished plastic in some amount, usually in such tiny amounts that it won’t harm you. These compounds are absolutely necessary because they help impart many desirable properties on the bulk plastic materials, such as making it “plastic” - flexible, bendable, without breaking or cracking.  Other modifiers help impart a shiny or dull finish, UV resistance, stiffness even when slightly heated, or hardness, etc.  So, the bottom line is that PET will always contain some other substance depending on its particular end use.

I could go on and on, but I think you get my point – that common consumer plastic products don’t just contain the basic carbon and hydrogen atoms that form that basic plastic.  These modifiers, additives, plasticizers, etc., are both simple and complex compounds.  And it is these compounds that contain the potential threat to our long-term health.  Some compounds will introduce the nitrogen atom, sulfur atom, chlorine atom, and/or a metal atom as part of their chemical makeup, to name a few.  When decomposed under high heat (as in a microwave) and/or flame (as in a fire or charcoal grill), the nitrogen, sulfur, chlorine, metal, and other elements can combine with carbon to produce some of the most toxic substances known to man.  Well, this sounds scary - at first.  Someone could argue that a charcoal grill can produce dangerous substances.  Well, yes, but no as well.  While in reality a charcoal grill can produce and impart dangerous harmful chemicals into your meat and other grilled food products, the reality also exists that such substances are produced in such nearly undetectable amounts that their EFFECTIVE toxicity is equally nearly non-existent.

The American and Worldwide Public is scared into believing that ALL harmful and dangerous toxic substances are truly deadly.  When one hears the term “carcinogen”, the ignorant Public assumes it’s a terrible horrible substance.  The truth is that these substances, both natural and synthetic, now exist in our world – the “chemical soup” I earlier mentioned.  Consequently, the American and Worldwide Public ignore the true definition of Toxicity.  Toxicity of any substance is a function of time (exposure) and concentration.  If you ingested sugar in small amounts it would not be harmful (except maybe to your waistline).  In larger amounts, it would pose medical issues, such as diabetes, but it still is not toxic.  If ingested in very large amounts, as in a dozen or more cups per single sitting, sugar does become (immediately) toxic.  The exact same example applies to any toxic substance, except that the amounts (concentrations) and exposure (time) are obviously very different.  

For example, if you minimize your exposure to nail polish, for instance, to just a few minutes per week and ventilate the room as your nail polish dries, you shouldn’t see any long-term effects. However, if you were exposed to nail polish vapors (or in liquid form) constantly 16 hours per day 7 days a week, you would be exposed to dangerously toxic levels and may experience immediate side-effects or irreparable harm.  (Google “composition of nail polish” and you will find several online articles about its ingredients, some of which can be cancerous and/or toxic - but again only if constantly exposed to them.)


I realize that your question was provided a "cut and dry answer", but you must realize in the first place that what you ask has no easy answer.  The chemical, physical, and health properties of the world's bulk commodity plastics and substances is more than the subject of industrial chemistry and science.  Its a global industry that's been researched, studied, and invested in for decades.

---------- FOLLOW-UP ----------

QUESTION: Thank you so much for answering my previous question. anyways, would you happen to know the answers to the following:

1. What is the difference among purified, mineral and distilled bottled water?
2. Is one type better than the other? Why?
3. Do they undergo the same processes?

Again, thank you very much! :)

Answer
Hello Melinda - I sincerely apologize in that it is taking a long time to respond to your question.  I have been out of the office away from home on a time-consuming project for my company.  I hope to provide a complete answer in a few days.  Again, my sincere apology.