Aspartame and Formaldehyde (or not…)

A possibly easier to read version of this better for pinting is available at

There is also a separate entry which is a response to a Joe Mercola article posted to the Huffington Post which repeated some of the claims refuted here, as well as some additional ones.


Aspartame, more commonly known as NutraSweet, is frequently claimed to have any number of ill effects in the body. This article will focus on the claim that aspartame contains formaldehyde, leading to toxic effects in the body (such as headaches), and will also touch on the claim that it is a carcinogen (cancer causing agent). There are additionally claims that aspartame leads to seizures, but this is a much less popular one (perhaps because the NutraSweet acknowledges the danger in the small amount of PKU sufferers for which it would affect). Hopefully the reader will be convinced it is true that one of the by-products of the breakdown of aspartame is formaldehyde, this does not represent any actual health hazard.

Just what is aspartame?

Aspartame is a low-caloric sweetener (i.e. alternative to sugar). Wikipedia describes aspartame as1

a methyl ester of the dipeptide of the natural amino acids L-aspartic acid and L-phenylalanine. Under strongly acidic or alkaline conditions, aspartame may generate methanol by hydrolysis. Under more severe conditions, the peptide bonds are also hydrolyzed, resulting in the free amino acids

Claims and Discussion

A common claim is that aspartame contains formaldehyde which builds up in the body and creates all manner of ills. Others have claimed that it is a carcinogen (cancer causing agent) despite there being no studies that really demonstrate that.
Mark D. Gold and Ralph Walton are two of the more prolific writers on this topic out there. Gold’s website has a section title “Formaldehyde Poisoning from Aspartame“, which has the following:

In 1997 there was an increase in aspartame users reporting severe toxicity reactions and damage such as seizures, eye damage and vision loss, confusion, severe migraines, tremors, depression, anxiety attacks, insomnia, etc. In the same years, Ralph Walton, MD, Chairman, The Center for Behavioral Medicine showed that the only studies which didn’t find problems with aspartame where those funded by the manufacturer (Monsanto).

Given the agreement amongst independent scientists about the toxicity of aspartame, the only question was whether the formaldehyde exposure from aspartame caused the toxicity. That question has now been largely answered because of research in the late 1990s.
The following facts shown by recent scientific research:

  1. Aspartame (nutrasweet) breaks down into methanol (wood alcohol).
  2. Methanol quickly converts to formadehyde in the body.
  3. Formaldehyde causes gradual and eventually severe damage to the neurological system, immune system and causes permanent genetic damage at extremely low doses.
  4. Methanol from alcoholic beverages and from fruit and juices does not convert to formaldehyde and cause damage because there are protective chemicals in these traditionally ingested beverages.
  5. The most recent independent research in Europe demonstrates that ingestion of small amounts of aspartame leads to the accumulation of significant levels of formaldehyde (bound to protein) in organs (liver, kidneys, brain) and tissues.
  6. Excitotoxic amino acids such as the one which is immediately released from aspartame likely increases the damage caused by the formaldehyde.

What the science says

While it is true that aspartame does break down into methanol then formaldehyde, it actually happens much more in fruit juices (about 2x in a banana, or 6x in an 8oz glass of tomato juice2). Gold attempts to address this in item 4, but simply waves his hand as an explanation for why it can be ignored. The fact is that it simply is not enough to do anything and your body easily disposes of it.
The above quoted article has one of the more untrue statements you can find. Not only do “non-independent” researchers find no problems, “independent” ones did not either. Instead what you will find are people making hypothetical claims which are not backed by anything. Gold and Walton are excellent at taking a statement by one scientist and using it as an explanation for why aspartame has been found to be bad, when in fact it has not. In other words, they start with the premise that aspartame is harmful then look for explanations for why it might be.

The Walton set of research is frequently cited, but let’s break it down a bit. It actually was already rebutted here:

Dr Walton’s paper reveals that of the 92 pieces of “research,” 85 (not 84) are said to identify an adverse reaction to aspartame. However, of the 85:

  • Ten studies actually involve aspartate and not aspartame. Aspartate is the salt of aspartic acid. Aspartic acid is a very common component of food. These studies are therefore irrelevant to aspartame safety.
  • 18 of the studies do not actually draw any negative conclusions about aspartame.
  • Five are review articles, not peer-reviewed studies.
  • Two are “brief reports” or “case reports”, not peer-reviewed studies.
  • Five are anecdotes, based on the writers’ observations of patients.
  • 11 are conference proceedings, which are not peer-reviewed studies.
  • 19 are letters to various medical journals.
  • Three are different reports of the same study.
  • Two are exact duplicates of other documents appearing in the list.
  • Three are different reports of the same allegations.

Overwhelming indeed. My own analysis is available here. What I found entertaining is how many of them (18 or 19) don’t even find anything negative… yet Walton, either brazenly or unknowingly, still includes them in his number. All in all, Walton is quite sloppy.
The only reasonable study (which I believe is also the one being referenced in #5 above), but still frequently questioned is:

  1. Trocho, C., et al., 1998. “Formaldehyde Derived From Dietary Aspartame Vinds(sic) to Tissue Components in vivo,” Life Sciences, Vol. 63, No. 5, pp. 337+, 1998
Note the misspelling as “Vinds”… when it should be “Binds”. It’s generally cited as “Vinds” though.. a good indication that most of the sites claiming to do research are simply copy/pasting from this one guy.

…The administration of labelled aspartame to a group of cirrhotic rats resulted in comparable label retention by tissue components, which suggests that liver function (or its defect) has little effect on formaldehyde formation from aspartame and binding to biological components. The chronic treatment of a series of rats with 200 mg/kg of non-labelled aspartame during 10 days resulted in the accumulation of even more label when given the radioactive bolus, suggesting that the amount of formaldehyde adducts coming from aspartame in tissue proteins and nucleic acids may be cumulative. It is concluded that aspartame consumption may constitute a hazard because of its contribution to the formation of formaldehyde adducts.

One of the primary responses is from Tephyl, quoted by Butchko et al3:

However, according to Tephly (1999), the dose of aspartame used in the study (20 mg/kg body wt=2mg of methanol/kg body wt) would not yield blood methanol concentrations outside control values. Further, the administration of aspartame at 200 mg/kg body wt (equal to that in a single bolus of about 25 liters of beverage sweetened 100% with aspartame) to adult humans results in no detectable increase in blood formate concentrations (Stegink et al., 1981). Administration of [14C]methanol itself at 3000 mg/kg body wt to monkeys produces no detectable [14C]formaldehyde in body fluids and tissues (McMartin et al., 1979)…The lack of formaldehyde accumulation at very high doses of methanol question considerably the conclusion that formaldehyde adducts are forming from low doses of methanol (derived from high doses aspartame). Thus, Tephly (1999) concluded, “the normal flux of one-carbon moieties whether derived from pectin, aspartame, or fruit juices is a physiologic phenomenon and not a toxic event.”

To break it down:
  1. Formaldehyde build-up has not in fact been detected even when 200mg/kg is given to humans (which is a huge amount)
  2. Even when large does of direct methanol (which is what breaks down into formaldehyde) were given to monkeys, it did not produce formaldehyde build-up
  3. There are other explanations for the labelled-carbon staying in the body, aside from formaldehyde build-up which will also occur with other substances (such as fruit pectin).
Going back to the original comments about Gold and Walton, we have a situation of someone trying to explain the build-up for formaldehyde, when no other scientists are able to actually see a build-up in the first place. Instead it seems that the labelled molecules are making their way through the basic chemistry of the process, but the full molecule is not.

Systematic Reviews

Let’s continue one with some of the large overviews which discuss the overall safety of aspartame in the broader scope, and occasionally look at studies purporting to show harm.

US Food and Drug Administration (FDA)

Both the FDA and the European Commission have determined that aspartame is safe. However they kicked off additional reviews in response to a study done by the European Ramazzini Foundation (linked here4) that claimed to demonstrate that aspartame was a carcinogen. The European review found this to not at all be supported by the data. The US FDA decided to do its own separate review of the study and had similar findings5:

FDA has completed its review concerning the long-term carcinogenicity study of aspartame entitled, “Long-Term Carcinogenicity Bioassays to Evaluate the Potential Biological Effects, in Particular Carcinogenic, of Aspartame Administered in Feed to Sprague-Dawley Rats,” conducted by the European Ramazzini Foundation (ERF), located in Bologna, Italy. FDA reviewed the study data made available to them by ERF and finds that it does not support ERF’s conclusion that aspartame is a carcinogen. Additionally, these data do not provide evidence to alter FDA’s conclusion that the use of aspartame is safe.


Considering results from the large number of studies on aspartame’s safety, including five previously conducted negative chronic carcinogenicity studies, a recently reported large epidemiology study with negative associations between the use of aspartame and the occurrence of tumors, and negative findings from a series of three transgenic mouse assays, FDA finds no reason to alter its previous conclusion that aspartame is safe as a general purpose sweetener in food.

Kind of interesting that the folks doing the study were not willing to actually submit it to a full review. If you take a look at the study’s tables (here and here), the bit that stands out to me is the lack of a consistent dose-response effect as you get higher doses of aspartame. They had to get up to an insane amount (2500mg/kg… or the equivalent of 500mg/kg for humans) to get a statistically significant effect.

European Commission – Scientific Committee on Food

For reasons unknown, people against Aspartame link to to the “European Commission updates their opinion” study as if the EC had determined that aspartame was now unsafe. The update was kicked off because of the Ramazzini Foundation study claiming carcinogenity. If you actually read the update, it is quite clear that they very much still find it to be safe.

Some important bits from the text (in all cases emphasis is my own)6:

The estimates of intake by mean and high level consumers are fairly consistent between European countries even though slightly different approaches were used. High level consumers, both adults and children, are unlikely to exceed the ADI of 40 mg/kg bw for aspartame. Special groups such as diabetics that are likely to be high consumers of foods containing aspartame are also well below the ADI. Therefore, from the available data it appears that no group is likely to exceed the ADI for aspartame on a regular basis.

All this is really saying is that the actual amount that most people would consume is well below the worldwide maximum level allowed (40-50 mg/kg).

If you view the table in the document, you can see that the mean is in the 2-3mg/kg bw/d, with high levels around 6-10.

Animal studies have demonstrated that the metabolic breakdown products of aspartame are absorbed and metabolised similarly whether they are given alone or derived from aspartame. The extensive presystemic metabolism of aspartame results in little or no parent compound reaching the general circulation.

This is in alignment to the Butchko/Tepyhl comments above: aspartame by-products (methanol, then formaldehyde) to not make it into the bloodstream.

And the key parts:

The aspartate component is rapidly metabolised and thus the plasma aspartate concentrations are not significantly elevated following aspartame doses of 34 to 50 mg/kg bw, whereas plasma Phe concentrations may increase depending on dose (Stegink, 1984). Methanol is also rapidly metabolised and blood levels are usually not detectable unless large bolus doses of aspartame (>50 mg/kg bw) are administered.

Trocho is discussed:

…Besides the fact that aspartame at high doses has never induced liver cancer in rats, Trocho’s studies did not identify the radioactivity found in the proteins and DNA. Consequently, the formation of adducts of formaldehyde on the proteins and nucleic acids from aspartame, in vivo, remains to be proved

French Food Safety Agency (AFSSA)

The AFSSA published its own systematic review (here hosted on the UK Food standards agency… FDA equivalent). They go over much of the same material as those above. On the subject of the aspartame leading to headaches, they have to say7:

Another study…was also a randomised double-blind placebo-controlled cross-over trial, concluded that aspartame was no more likely than placebo to trigger headaches (Schiffman et al., 1987). This study consisted of 40 subjects who complained of aspartame-related headachesWhile 35% of subjects developed headaches while on aspartame, 45% developed headaches while on placebo.

I found it interesting that the Shiffman study actually used people who were already pre-disposed to believe that they got headaches from aspartame, and even then it could not be demonstrated.


The fact of the matter is there is not a convincing body of evidence (or none at all depending on how you look at it) to indicate that there is any reason to be concerned with normal intake of foods and beverages containing aspartame–unless you somehow manage to consume 12 liters of soda in a single sitting, in which case you have worse things to worry about. If there is interest, another article could focus on the supposed “excitotoxin” aspects of aspartame and some of the other proposed effects.The problem with these claims is that there is a large amount of urban myth around aspartame which do not have any studies (or reproduced studies) to back them up. They are essentially made up from whole cloth, which actually makes them more difficult to disprove. If there are specific studies that you have found convincing, then they could serve as a new jumping off point for another essay. Until then, there seems no reason to not consume diet beverages and other “light” foods.
UPDATE July 15, 2012 – Corrected external link to rebuttal of Walton’s “independent” aspartame studies

1 – Wikipedia page on aspartame. Used for general overview. Visited 3/5/2010

2 Magnuson, B. “Straight facts on aspartame & health”. The Beverage Institute. Visited 6/13/2010. The actual numbers quoted come from the peer-reviewed paper by the same author, but I was unable to find a working full text link.

3 Butchko, HH., Stargel, WW., Comer, CP., Mayhew, DA. “Aspartame: Review of Safety”. Regulatory Toxicology and Pharmacology 35, S1–S93 (2002)

4 Soffritti, M., Belpoggi F. et al. “First Experimental Demonstration of the Multipotential Carcinogenic Effects of Aspartame Administered in the Feed to Sprague-Dawley Rats”. Environ Health Perspect. 2006 March; 114(3): 379–385.

5 US Food and Drug Administration. “FDA Statement on European Aspartame Study”. CFSAN/Office of Food Additive Safety. April 20, 2007. Accessed 6/13/2010

6 European Commission Scientific Committee on Feed. “Opinion of the Scientific Committee on Food:Update on the Safety of Aspartame”. December 4, 2002. Accessed 6/13/2010.

7 French Food Safety Agency (AFSSA). “Opinion on a possible link between the exposition to aspartame and the incidence of brain tumours in humans”. May 7, 2002. Accessed 6/13/2010.

Water Bottles and Cancer

A printable and easier to read version can be found at:



I thought it would be interested to look into the oft-quoted idea that water bottles are not reusable and that if you do anything other than drink from them and toss them, that you would get cancer. I personally had not heard many of the claims and in even looking them up, the first few results were usually previous debunkings. This almost made be stop by I figured for my few readers I may as well summarize some of the results. Plus I thought it would be nice to look into something where there was nobody I could offend, which is nice. This is part of an ongoing series that has included energy drinks and water intake requirements.

A comment-enabled version can be found on my blog at:

Note: BPA will be covered in another essay, as the FDA and CDC are currently awaiting for new studies to be completed. They were supposed to report back Nov 30, but this has come and gone. Currently the official position is that BPA as it is currently used is safe.


Your water bottle is not going to kill you. The best thing to do any time you hear that some every day item is going to kill you is to head on over to Snopes. Most stories like this are quickly found to be based on complete fabrications. This particular one happens to have very minute amounts of “real” science (e.g. dioxins and DEHA do exist and DEHA is in microwave-safe plastics) but that actual effects are in no way realistic. Additionally, DEHA is not actually carcinogenic as far as anyone can tell. Whether or not you personally believe in any claim of this sort, please refrain from passing it on before you have validated that it is credible.


I am not a doctor or scientist, no words of mine should be construed as medical advice. My intent is only to find the best available scientific or medical evidence for or against claims that comes for authoritative sources. If you have credible studies that would contradict them, please let me know.


Claim 1: Leaving a bottle of water in the car can make it cancerous

Personally I had never really heard about this one, but I did some searching and it looks to be a popular one, having originated with an email hoax purporting to come from “Johns Hopkins” and claiming that leaving a water bottle in the car can cause it to leak “dioxins”. Occasionally the email will include the claim that Sheryl Crow was on Ellen to warn others about this happening to her.


From one blog that has pasted the email (and claims it came from a breast cancer doctor): [1]

Cancer Update from Johns-Hopkins

Bottled water in your car isvery dangerous!

On the Ellen show, Sheryl Crow said this is what caused her breast cancer. It has been identified as the most common cause of the high levels of dioxin in breast cancer tissue.

Sheryl Crow’s oncologist told her:

women should not drink bottled water that has been left in a car.The heat reacts with the chemicals in the plastic of the bottle which releases dioxin into the water. Dioxin is a toxin increasingly found in breast cancer tissue. So please be careful and do not drink bottled water that has been left in a car. Pass this on to all the women in your life.

What the science says

Let’s get the Sheryl Crow part of it out of the way right away. On her official site she posted real information about dioxins that specifically goes against the claim (i.e. she acknowledges that it is a hoax). It can currently be found on page 23 of her “news items” (the items are chronological, and this item is from October of 2006). It is a news item called “What You Need to Know About Dioxins (Updated with Notes from Gregg Dempsey”. In case that link doesn’t get you there, an Internet Archive version exists of her older site which had the same news item. She actually ends up quoting from some of the same stuff that will come below.
Regardless, I think it should be stressed as always that celebrities should not be where you get your science or medical information from. This also goes for the ones I agree with.

The Internet is flooded with messages warning against freezing water in plastic bottles or cooking with plastics in the microwave oven. These messages, frequently titled “Johns Hopkins Cancer News” or “Johns Hopkins Cancer Update,” are falsely attributed to Johns Hopkins and we do not endorse their content.

Freezing water does not cause the release of chemicals from plastic bottles.

Additionally, they have another response that goes into some more detail[3]:

Question: What do you make of this recent email warning that claims dioxins can be released by freezing water in plastic bottles?

Answer: No. This is an urban legend. There are no dioxins in plastics. In addition, freezing actually works against the release of chemicals. Chemicals do not diffuse as readily in cold temperatures, which would limit chemical release if there were dioxins in plastic, and we don’t think there are.

The FDA has a page about dioxins. You are exposed to it quite often. Their page makes absolutely no mention of plastic bottles.

Technically some studies have shown that high levels of exposure could potentially cause cancer[4]:

G2. Why are people concerned about dioxins?

One of the main concerns over health effects from dioxins is the risk of cancer in adults. Several studies suggest that workers exposed to high levels of dioxins at their workplace over many years have an increased risk of cancer. Animal studies have also shown an increased risk of cancer from long-term exposure to dioxins.

G4. How might I be exposed to dioxins?

Most of the population has low-level exposure to dioxins. Although dioxins are environmental contaminants, most dioxin exposure occurs through the diet, with over 95% coming through dietary intake of animal fats (see also F3 and F4). Small amounts of exposure occur from breathing air containing trace amounts of dioxins on particles and in vapor form, from inadvertent ingestion of soil containing dioxins, and from absorption through the skin contacting air, soil, or water containing minute levels of dioxins.

But again it has absolutely nothing to do with plastic bottles (or even, as far as I know, any plastics you would use regularly).


It is true that dioxins could be potentially hazardous, but it does not seem that the average person would be getting anywhere near the exposure that could be harmful. And it certainly has nothing whatsoever to do with water bottles.

Claim 2: Heating of Freezing Water Bottles Causes them to Leach Chemicals such as DEHA


As a seventh grade student, Claire Nelson learned that DEHA, di(ethylhexyl)adepate, considered a carcinogen, is found in plastic wrap. She also learned that the FDA had never studied the effect of microwave cooking on plastic-wrapped food. Claire began to wonder: “Can cancer-causing particles seep into food covered with household plastic wrap while it is being microwaved?”

Three years later, with encouragement from her high school science teacher, Claire set out to test what the FDA had not. Although she had an idea for studying the effect of microwave radiation on plastic-wrapped food, she did not have the equipment. Eventually, Jon Wilkes at the National Center for Toxicological Research in Jefferson, Arkansas, agreed to help her. The research center, which is affiliated with the FDA, let her use its facilities to perform her experiments, which involved microwaving plastic wrap in virgin olive oil. Claire tested four different plastic wraps and “found not just the carcinogens but also xenoestrogen was migrating [into the oil]….” Xenoestrogens are linked to low sperm counts in men and to breast cancer in women.


On Channel 2 (Huntsville, AL) this morning they had a Dr. Edward Fujimoto from Castle Hospital on the program. He is the manager of the Wellness Program at the hospital. He was talking about dioxins and how bad they are for us. He said that we should not be heating our food in the microwave using plastic containers. This applies to foods that contain fat. He said that the combination of fat, high heat and plastics releases dioxins into the food and ultimately into the cells of the body. Dioxins are carcinogens and highly toxic to the cells of our bodies.

What the Science Says

Others have done better research on this hoax (actually for both parts), a good one being at As usual, Snopes is a good source on this one ( Another one to take a look at
I actually couldn’t put it better than Snopes:

It’s a pretty good assumption that if using plastic containers in microwaves posed a significant risk of cancer, you’d be hearing it somewhere other than an e-mail forward of an anomymous summary of a morning news spot on a Hawaiin television station

Replace the item and the danger, and you have a large percentage of all the supposed health hazards out there from normal household items.. which are also not backed by any actual science.
From (arguably potentially biased) site[5]:

The student’s thesis incorrectly identifies di(2-ethylhexyl) adipate (DEHA), a plastics additive, as a human carcinogen. DEHA is neither regulated nor classified as a human carcinogen by the U.S. Occupational Safety & Health Administration, the National Toxicology Program or the International Agency for Research on Cancer, the leading authorities on carcinogenic substances.

In 1991, on the basis of very limited data, the U.S. Environmental Protection Agency classified DEHA as a “possible human carcinogen.” However, in 1995, EPA again evaluated the science and concluded that “…overall, the evidence is too limited to establish that DEHA is likely to cause cancer.”

Further, DEHA is not inherent in PET as a raw material, byproduct or decomposition product. DEHA is a common plasticizer that is used in innumerable plastic items, many of which are found in the laboratory. For this reason, the student’s detection of DEHA is likely to have been the result of inadvertent lab contamination. This is supported by the fact that DEHA was detected infrequently (approximately 6% of the samples) and randomly, meaning that the frequency of detection bore no relationship to the test conditions.

Moreover, DEHA has been cleared by FDA for food-contact applications and would not pose a health risk even if it were present.

Finally, in June 2003, the Swiss Federal Laboratories for Materials Testing and Research conducted a scientific study of migration in new and reused plastic water bottles from three countries. The Swiss study did not find DEHA at concentrations significantly above the background levels detected in distilled water, indicating DEHA was unlikely to have migrated from the bottles. The study concluded that the levels of DEHA were distinctly below the World Health Organization guidelines for safe drinking water.

Or if you don’t trust “”, how about the American Cancer Society[6].

These emails are apparently based on a student’s college thesis. In fact, DEHA is not inherent in the plastic used to make these bottles, and even if it was the U.S. Environmental Protection Agency (EPA) says DEHA “cannot reasonably be anticipated to cause cancer, teratogenic effects, immunotoxicity, neurotoxicity, gene mutations, liver, kidney, reproductive, or developmental toxicity or other serious or irreversible chronic health effects.” Meanwhile, the International Agency for Research on Cancer (IARC), says diethylhexyl adipate “is not classifiable as to its carcinogenicity to humans.”

The IARC study that both reference can be found online here. The above have already quoted it, so the link is just for reference.

Or how about the EPA (you will note that they make no mention of water bottles)[7]:

What is di(2-ethylhexyl) adipate?

Di(2-ethylhexyl) adipate is a light-colored, oily liquid with an aromatic odor.

What are di(2-ethylhexyl) adipate’s health effects?

Some people who drink water containing di(2-ethylhexyl) adipate well in excess of the maximum contaminant level (MCL) for many years could experience toxic effects such as weight loss, liver enlargement, or possible reproductive difficulties.

How does di(2-ethylhexyl) adipate get into my drinking water?

The major source of di(2-ethylhexyl) adipate in drinking water is discharge from chemical factories.


The FDA, EPA, and American Cancer Society are well aware of DEHA,water bottles and plastics. They make absolutely no claims about them being carcinogenic when frozen or heated. In fact they make sure to point that these claims are specifically untrue.

Claim 3: Water bottles are unsafe for re-use because of bacteria


Well, yeah. You should re-use any container without rinsing it with soap and water. Why would water bottles be any different. Claiming that water bottles are any different means that as soon as you open a bottle of water you must throw it away after the first drink if you don’t finish it. Does that make any sense?

Further References

Not surprisingly, Brian Dunning of Skeptoid covered this already (in 2007 no less) at:

It has also been covered on pretty much every email-hoax debunking site.


1 Smith-Batchen, Lisa. “Cancer Update from Johns Hopkins”. April 11, 2009.

2 Johns Hopkins School of Public Health.


4 Food and Drug Administration. “Questions and Answers about Dioxins”. Visited 2009/12/06

5 American Chemistry Council. “FAQs: The Safety of Plastic Beverage Bottles”. Visited 12/6/2009

6 American Cancer Society.

7 Environmental Protection Agency. “Basic Information about Di(2-ethylhexyl) adipate in Drinking Water”.