The truth about plastic containers, bottles, and packaging

[Fat Guy]

What's the hard science on plastic containers, bottles and packaging? I understand that disposable plastic is often bad environmentally (though there is room for debate on, for example, the paper v. plastic bag issue), but I'm talking about the health issues. Is there bad stuff in the plastic that leeches into food and therefore us? Is it totally harmless? Does it depend on type? Is it only a problem at higher (or lower) temperatures?

[Chris Amirault]

And, while we're digging into these questions: says who? Whenever I've tried to figure this out, the references seem just as hard to sort out as the "science."

[CFT]

There was some hoo-ha about the plasticisers from clingfilm leaching out if in contact with fatty foodstuff. But it appears that the levels were safe.

http://www.foodplast.com/index.asp?page=31

Recently there has been a scare in the UK regarding BPA in babies feeding bottles. Most retailers have withdrawn these products and stock non-BPA versions.

[Shelby]

I wonder about this topic all of the time.

For example, yesterday I had large amounts of homemade chicken stock to freeze. What would one use besides a plastic container?

[Chris Amirault]

so let's take BPA as an example.

Here's the wikipedia entry on Bisphenol-A:

Known to be estrogenic since the mid 1930s, concerns about the use of bisphenol A in consumer products were regularly reported in the news media in 2008 after several governments issued reports questioning its safety, prompting some retailers to remove products containing it from their shelves. A 2010 report from the United States Food and Drug Administration (FDA) raised further concerns regarding exposure of fetuses, infants and young children. In September 2010, Canada became the first country to declare BPA as a toxic substance. In the European Union and Canada BPA use is banned in baby bottles. ...

Bisphenol A is an endocrine disruptor, which can mimic the body's own hormones and may lead to negative health effects. Early development appears to be the period of greatest sensitivity to its effects. Regulatory bodies have determined safety levels for humans, but those safety levels are currently being questioned or under review as a result of new scientific studies.

Here's the Bisphenol-A advocacy organization -- and, if anything needs an advocacy organization these days, it's BPA -- on the matter:

Bisphenol A (BPA) is one of the most extensively tested materials in use today. BPA has been safely used in consumer products and researched and studied for over 40 years. The weight of scientific evidence clearly supports the safety of BPA and provides strong reassurance that there is no basis for human health concerns from exposure to BPA. ...

Safety assessments of bisphenol A (BPA) conclude that the potential human exposure to BPA from polycarbonate plastics and epoxy resins is more than 400 times lower than the safe level of BPA set by the U.S. Environmental Protection Agency. This minimal level of exposure to BPA poses no known risk to human health.

The use of polycarbonate plastic and epoxy resins for food contact applications has been and continues to be recognized as safe by the U.S. Food and Drug Administration, the European Commission's Scientific Committee on Food, the United Kingdom Food Standards Agency, and other regulatory agencies worldwide.

And here's the FDA weighing in:

Studies employing standardized toxicity tests have thus far supported the safety of current low levels of human exposure to BPA. However, on the basis of results from recent studies using novel approaches to test for subtle effects, both the National Toxicology Program at the National Institutes of Health and FDA have some concern about the potential effects of BPA on the brain, behavior, and prostate gland in fetuses, infants, and young children. In cooperation with the National Toxicology Program, FDA’s National Center for Toxicological Research is carrying out in-depth studies to answer key questions and clarify uncertainties about the risks of BPA.

Needless to say, there are a gazillion articles, blog entries, and more out there that proclaim loudly that BPA should be banned. I'll let you wade through those.

[Darienne]

This question has been bothering me lately too.

Because I now have considerable hand issues, I have been drinking for the last five years all my beverages, hot and cold, from plastic mugs. These mugs are all quite old, second hand because when this need for a lighter mug first appeared, there was a dearth of plastic on the market. Folks were moving to earthenware, etc, for outdoor eating. A plastic mug weighs about 4 oz; a ceramic or glass at least 10 oz and most often about a pound.

Our daughter noticed this at Christmas and began to harangue heavily on the dangers of what I was doing.

Answers? Perhaps I am at almost 70, too old for it to make much of a difference? Gagghh. I can't believe I am almost 70. Sorry I mentioned it.

[gfweb]

This is an area filled with junk science and over-interpretation. Any doc will tell you that causing cancer in lab animals is far from being applicable to humans. Lab animals are bred to be prone to developing cancers and are too sensitive a test to be completely predictive.

Another issue that rarely gets discussed is dosage. Biological phenomena usually have a threshold beneath-which there is no effect. A common error is to look at two or three high doses of a compound, see that each grows cancers, plot a graph and then extrapolate the rate to lower untested amounts. We see this sort of stuff in the dubious reports of Maillard-induced carcinogens in French Fries etc.

An example of the issue would be if you made a graph of doneness at various temperatures of sous vide cooking. Say you plotted the doneness at 80C, 70C and 50C for a piece of meat and then drew a line down to 37C. That line would predict a degree of doneness at 37. But we know that there's a threshold beneath-which no cooking occurs and that 37 is normal body temp.

Not to say that there are no worries about chemicals causing problems, but that the science isn't as clear as uncritical newspapers would have us believe.

[Chris Amirault]

Answers? Perhaps I am at almost 70, too old for it to make much of a difference?

I think you're asking a good question, one that food safety people want us to remind ourselves. We're always dealing with risk reduction, not elimination, and reduction involves an awareness of statistics that are a lot more complicated than "when in doubt, throw it out." In addition, given the amount of plastic that comes in contact with our food before you poke it with a fork, you couldn't throw it all out even if you wanted to do so.

Edited January 5, 2011 by Chris Amirault
ETA Darienne's quotation -- CA (log)

[emannths]

Maybe we can knock out some of the questions/concerns one-by-one. So while the answer to whether plastic containers are "safe" on the whole may be difficult to determine, I think some fears can be allayed. For example...

There is usually concern about reusing plastic containers. For example, some say not to reuse a water bottle. I can't see any scientific rationale to this. The first fill will contain the highest concentration of "contaminants," and each subsequent fill should have lower and lower concentration (a good analogy: think about the color of your tea when you reuse a tea bag--each time you reuse it, the color gets lighter). Perhaps there's some concern that over time the plastic degrades, but this would happen regardless of whether or not the container if filled with its original contents or something else.

My conclusion: don't worry about reusing plastic containers. If there's any difference at all, it's probably better than using a new container.

There's also a concern about freezing food in plastic containers. Here's what Johns Hopkins has to say about this: "Freezing water does not cause the release of chemicals from plastic bottles." Good enough for me.

Also, concerns about one type of plastic should not apply to other types. For example, concerns about bisphenol-a (a polycarbonate precursor), should not extend to polyethylene (recycling code 2) or polypropylene (#5). Additionally, the concerns about phthalate exposure from PET products (#1) should not be confused with these other products.

Finally, if you're concerned enough about bisphenol-a that you're going to stop using polycarbonate products, you'll have to stop using most canned products as well, as the cans are lined with an epoxy that uses bisphenol-a as a precursor. It can also be found in thermal paper (credit card receipts, etc), with some indicating this may be the leading source of exposure for most people.

My personal take: there's no use trying to stay ahead of the curve on things like this. Plastic products are so pervasive that trying to reduce you exposure will only net a reduction on the order of 1 (e.g., maybe you cut your exposure in half). Most of the concern about health effects stems from concerns that even very low exposure levels result in major health problems, so addressing this would necessitate an exposure reduction of many orders of magnitude. Doing so would take waaaaaaaaay too much time and effort. If you're willing to put in the time and effort, it would be better spent simply exercising and eating healthier food instead of worrying about your containers.

[Jenni]

I was under the impression, rightly or wrongly, that the main problem with plastics was to do with having them in contact with hot food e.g. plastic wrapped food being microwaved, etc. Since I don't eat ready meals and don't enjoy drinking out of plastic mugs (tastes funny!) I have never really found it to be a problem.

[Chris Amirault]

emannths, can you give us a link to, or provide here, an introduction into the basics of food plastics? Some of us don't know our polyethylenes from our polypropylenes.

[emannths]

emannths, can you give us a link to, or provide here, an introduction into the basics of food plastics? Some of us don't know our polyethylenes from our polypropylenes.

I think the simplest way is to use the Resin ID Codes as a sort-of portal to look for more details about the various plastics used for food. No. 1, 3, and 7 tend to have the most concerns associated with them, while 2, 4, 5, and 6 invite much less controversy.

[Boilerfood]

I wonder about this topic all of the time.

For example, yesterday I had large amounts of homemade chicken stock to freeze. What would one use besides a plastic container?

I had this exact situation a couple of days ago, and chose old plastic milk jugs, reasoning that Milk is a relatively well regulated food stuff. Plus they are convenient.

[Shelby]

I wonder about this topic all of the time.

For example, yesterday I had large amounts of homemade chicken stock to freeze. What would one use besides a plastic container?

I had this exact situation a couple of days ago, and chose old plastic milk jugs, reasoning that Milk is a relatively well regulated food stuff. Plus they are convenient.

That's an idea I hadn't thought of. The bad thing for me is that storing a lot of those in the freezer would be difficult.

[andiesenji]

This is an area filled with junk science and over-interpretation. Any doc will tell you that causing cancer in lab animals is far from being applicable to humans. Lab animals are bred to be prone to developing cancers and are too sensitive a test to be completely predictive.

Another issue that rarely gets discussed is dosage. Biological phenomena usually have a threshold beneath-which there is no effect. A common error is to look at two or three high doses of a compound, see that each grows cancers, plot a graph and then extrapolate the rate to lower untested amounts. We see this sort of stuff in the dubious reports of Maillard-induced carcinogens in French Fries etc.

An example of the issue would be if you made a graph of doneness at various temperatures of sous vide cooking. Say you plotted the doneness at 80C, 70C and 50C for a piece of meat and then drew a line down to 37C. That line would predict a degree of doneness at 37. But we know that there's a threshold beneath-which no cooking occurs and that 37 is normal body temp.

Not to say that there are no worries about chemicals causing problems, but that the science isn't as clear as uncritical newspapers would have us believe.

I agree. I've read a number of these studies and it all depends on where the researcher stands as to how his results are couched. It's interesting that two sets of researchers, testing the same materials, with similar laboratory equipment and functions, can get widely different results.

In many cases they test the fumes from plastics at high heats, which break down the component parts and have found those fumes to be toxic at certain levels.

This stuff stinks! How many people in daily use, are going to stand around and breathe in an acrid, oily smoke? Not many, unless they are totally weird.

The plastics intended for use in food service have been tested extensively and in my opinion, are safe, if used as intended by the manufacturer.

I won't use anything made of recycled plastics with food because there is often other stuff in the mix, such as dyes, inks, and so on.

I don't expose my plastic food containers to prolonged sunlight because that has been proven to have an effect on the plastic after long exposure and I don't expose them to high heat and don't use them in the microwave unless they are intended for such use.

Common sense should dictate how anyone uses these things. I have some plastic mugs and tumblers that are probably forty years old and still have a shiny, unbroken surface. As long as they aren't discolored, cracked or showing surface wear from the plastic breaking down, I will continue to use them.

Much of my opinion of this testing brouhaha harks back to when sodium cyclamate was banned from use in the U.S. because of "possible" carcinogens because rats fed amounts that were equivalent to a human consuming more than a pound a day, produced tumors in rats. As this stuff is 35 to 40 times as sweet as sugar, the likelihood of anyone consuming this amount for a prolonged period is ridiculous.

One counter researcher proved that the same amount of saccharin (legal) would be fatal, as would plain salt.

Go figure!

[emannths]

Ok, here's a quick primer:

Polyethylene terephthalate (aka PET, PETE; #1)

Uses: Water and soft drink bottles, films, fibers (including Polar Fleece)

PET is made by reacting terephthalic acid with ethylene glycol. Sometimes other monomers are included in the reaction, such as cyclohexane dimethanol and isophthalic acid. Orthophthalates, the toxic plasticizers used in PVC, are not generally used in the reaction. Plasticizers are not used with PET. Sometimes, a layer of aluminum or polyvinyl alcohol (PVA) is added to help with barrier properties (i.e., to exclude oxygen or keep in carbonation). Neither of these additives have associated health concerns (PVA is used in Elmer's Glue and many eyedrops, for example).

Potential health concerns: minimal. There are plausible mechanisms by which the PET may degrade to create toxic phthalates, but this hasn't really been observed. Additionally, antimony is used as a catalyst in PET production, and is therefore present in trace amounts in the PET container. Whether it leeches in to your drink, and whether that would cause problems, is undetermined. [source]

High-density polyethylene (aka PE, HDPE; #2)

Uses: Milk jugs, margarine tubs, water pipes, grocery bags, hip implants...

HDPE is made using ethylene gas and a catalyst. Plasticizers are not used with HDPE. Degradation of HDPE is notoriously slow, though it can be accelerated with exposure to UV light. The degradation products are dependent on the mode of degradation, but can be expected to be an assortment of hydrocarbons, most being benign.

Potential health concerns: effectively none. I suppose you could get yourself worked up over the potential presence of catalyst (though this is usually not a heavy-metal catalyst), or the potential degradation products, but HDPE shouldn't have any more potential to harm you than anything else in your general environment.

Polyvinyl chloride (aka PVC; #3)

Uses: Pipes, tubing, plastic wrap (some formulations)

PVC is made from vinyl chloride. While vinyl chloride is highly toxic, once polymerized, the vinyl chloride is gone and therefore of little concern. PVC is often modified with additives and plasticizers to create the desired properties. It is often these additives that are the cause of much of the health concerns surrounding PVC.

Potential health concerns: moderate? The presence of unpolymerized vinyl chloride is a concern, as is the creation of toxic compounds by thermal degradation. PVC is generally heat-stable up to at least 200C, so as long as the PVC remains in contact with water, the risk is minimal. This is why microwaving foods, especially fatty foods, with PVC wrap, is not a great idea. The fat can splatter onto the plastic wrap, where it can heat the plastic wrap to over 100C (since it is no longer in contact with water). Additionally, because of the wide range of additives that may be included in a PVC product, it is difficult to determine the exact hazards. The good news is that PVC has long been recognized as a potential health hazard, so we have a relatively good idea about how to create, process, and use PVC products safely.

Low-density polyethylene (aka PE, LDPE, LLDPE; #4)

Uses: film, bags, trays, containers, waterproof coatings on cardboard liquid contains (e.g., juice and milk)

LDPE is chemically identical to HDPE, with the only difference being how much each chain branches (LDPE branches more), so please see the HDPE section for details.

Polypropylene (aka PP; #5)

Uses: Plastic hinges (e.g., Tic-Tac container), heat-resistant containers

The manufacture and chemical properties of PP are similar to those of PE, substituting propylene gas for ethylene gas in the manufacture.

Health concerns: minimal. The health risks are essentially identical to those for PE. However, because PP is generally used for higher-value uses, it is more likely to be modified with additives. In 2008, there was a report that some of these additives may potentially be a source of some potentially hazardous compounds. However, the concentration of these compounds was very low, and the compounds themselves are not intensely hazardous, so this shouldn't be a major concern given the current evidence.

Polystyrene (aka PS, #6)

Uses: Plastic utensils, some yogurt containers, foam cups

A synthetic chemist would tell you that PS is by dozens of different methods, but they all involve simply linking up a bunch of styrene molecules. It is sometimes copolymerized with other monomers to make tougher plastics (such as high-impact polystyrene and ABS, which is probably what the housings of most of your plastic items are made from), but these rarely see food contact.

Health concerns: minimal. PS has been evaluated as a food packaging material for over 50 years, and all governments (US, Europe, Hong Kong...) label it as safe. There may be underlying concerns about exposure to unpolymerized styrene, but you'll likely be exposed to more styrene from your food than from its container. It is also relatively heat stable.

A quick note on #7 plastics: #7 is a catch-all for anything listed above. So while all polycarbonate is #7, not all #7 is polycarbonate.

Polycarbonate (aka PC, #7)

Uses: Reusable water bottles, highly transparent food storage containers (e.g. some Cambro containers)

First we said that "#7" isn't specific enough. Well, PC sometimes isn't either. For these purposes, we're concerned about PC that is made from bisphenol-a (BPA), which encompasses most PC. However, it is certainly possible to make a plastic that would be called PC without using BPA. This is rare, though, and it should be safe to assume that unless a PC product says "NOT MADE WITH BPA," it's made with bpa.

Health concerns: moderate-significant. The concern with PC is both the presence of unreacted BPA and also the presence of BPA created as the PC degrades over time. While the leeching of minute amounts of precursor probably happens with all plastics, it's a much bigger concern for PC/BPA. This is because there are some studies that show that BPA can have health effects at extremely low concentrations by mimicking natural hormones. Strong bases (e.g., bleach) may accelerate the breakdown of PC into BPA. As I noted above, however, PC containers are hardly the only source of exposure to BPA, and so minimizing your use of a water bottle may have little net effect. And of course the science is inconclusive at this point as to both a) whether PC containers leech BPA and b) whether minute amounts of BPA have measurable heath effects.

Hopefully that gets you started. Most of the info is distilled from Wikipedia, with a few other sources thrown in, and then all run by my chemical-engineering-degree filter. While most of the info is pretty easy to find, it's often riddled with what seem like small errors (e.g., confusing teraphthalates with orthophthalates) that make a big difference in the final analysis.

ETA one last comment: The above summary deals mainly with the plastics themselves, and not the potential additives. Where common, I've tried to note them, but the presence of additives of course changes the analysis. If someone starts adding carcinogenic dyes to your milk container, it doesn't really matter how safe HDPE is, does it?

Edited January 5, 2011 by emannths (log)

[JBailey]

Emannths

That was a most interesting and fascinating primer, thank you. Does manufacturing of the plastics and plastic products in plants in the U.S., using chemicals and products sourced both domestically and off-shore make a difference in quality and safety of the output versus a plant located for cheaper labor in another part of the world? I think of the melamine (?) issues discovered in China over the last couple years in products like dog food and baby formula. Should we be looking for a 'made in America' or 'made in western Europe' sourcing labels?

In the meantime, I will be disposing of my platic bottles in the back seat of my Corvair without the seat belts!

[rooftop1000]

Since I have nothing Technical to add to this discussion...I will hit on re-using water bottles.

The worry is that many people Do Not Wash them in between uses...just take that last sip, close it up, and refill at next opportunity. On my last vacation I started the day with a fresh Diet Coke bottle and when it was empty just refilled it all day from public water fountains. Some normal person who drinks coffee in the morning might have just run with 1 bottle all week...

I caught a few seconds of this on the news a few days ago and the speaker said it's like using a dirty fork for a month.

tracey

[paulraphael]

My research corresponds prettly closely with emmanth's.

Here are my notes, which at the risk of oversimplifying the issues, are a bit easier to follow:

Recycling

Symbol Type Hazard

1 PET / PETE Don't Reuse

(porous / hard to clean)

2 HDPE No Known Hazards

3 PVC May leach various plasicizers

4 LDPE No Known Hazards

5 PP No Known Hazards

6 PS Can leach carcinogens /

endocrine disruptors

7 Other Many plastics with many characteristics.

Some contain BPA;

some are forms of PVC

It's certainly possible that closeer scrutiny will find more and more trace compounds with potential hazards in any of these materials. But this isn't limited to plastics; stuff leaches out of glass, ceramic glazes, and stainless steel as well. This is in fact the case with everything in the world: the more closely we look, the more potentially scary stuff we find. The trick is evaluating the risks, which requires educated (or wild) guesses.

Bear in mind that we're all gonna die from something.

[JasonW]

First off, excellent post by Emannths.

*** I would like to preface this post by saying I am not an expert and definitely do not have a chemical engineering background.

I also love wikipedia and never go a day without using it. However I feel that it is not the best source for topics without a good consensus in the scientific community. Regarding bisphenol A; I think alot of 'popular science' tends to find its way onto the internet and into wikipedia faster than any meta analyses or good systematic reviews.

Although alot more research is still needed, at the moment I believe there are some things we are fairly confident in:

1. some natural estradiols are carcinogens

2. BPA can mimic these effects

But the there is insufficient evidence to conclude:

1. BPA is associated with increased cancer incidence

2. early life BPA exposure leads to pre-neoplastic lesion

3. pre natal exposure to environmentally relevant doses of BPA increases markers for breast cancer risk in humans

To clear up some things that have been thrown around in the news or online:

1. low dose mouse studies have shown breast/prostate anomalies. Many of these studies used injections (not oral) and looked for enlarged prostates - which are not necessary pre-neoplastic (nor do pre-neoplastic lesions necessarily lead to neoplasia).

2. our diverse sources of BPA are way below (400x) the acceptable intake set by the EPA (although some of these figures are disputed by prominent endocrine/toxicological journals)

3. BPA can cause neurological changes in rats. These studies are not of the highest quality and have not shown great (or any) reproducibility.

Although Health Canada (first country) did ban BPA in polycarbonate baby bottles, they do state very strongly that there are no adverse effects on the general population.

I personally doubt there is any significant risk to our BPA consumption as in Nalgene bottles or canned foods but it is probably reasonable to go to greater lengths to protect babies even though the evidence is not that strong.

Just my 2 cents,

Jason

[Kent Wang]

Should I not use the plastic take-out / doggy bag containers in the microwave?

[paulraphael]

If you were convinced of the evils of BPA, you'd want to eliminate canned foods. The amount of bpa leached from a polycarbonate cambro container is trivial compared with what leaches into canned anything.

>> Should I not use the plastic take-out / doggy bag containers in the microwave?

Most takeout containers are polypropylene. I microwave them without a second thought.

[weinoo]

>> Should I not use the plastic take-out / doggy bag containers in the microwave?

Most takeout containers are polypropylene. I microwave them without a second thought.

Yes, but I'll bet you don't use them to store your mouse and rat foods.

[JasonW]

Does anyone use cling film or plastic wrap for blind baking tart shells? I've seen professionals use it and Claire Clark calls for it in her book. Any advantage over parchment or aluminum foil? perhaps better conformation to the dough? Does it stand the heat of a hot oven?

[andiesenji]

Does anyone use cling film or plastic wrap for blind baking tart shells? I've seen professionals use it and Claire Clark calls for it in her book. Any advantage over parchment or aluminum foil? perhaps better conformation to the dough? Does it stand the heat of a hot oven?

No, I use the very thin aluminum pie pans and put weights in them. They maintain the shape better and the upper edge protects the edge of the dough from getting too brown.