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How a Public Relations Campaign Deceives the Public About Formaldehyde Poisoning From Aspartame

October 15, 2000

I have recently been sent some information about aspartame and formaldehyde that looks like it might be part of one last public relations campaign to claim the chemical is 'safe'. The formaldehyde exposure number cited in the text is off by a factor of over 400,000 and would not be taken seriously by knowledgable scientists. The scientific literature cited has clearly not been read by the author. However, since a few consumers might inadvertently take the text seriously, I have chosen to point out some of the more obvious problems with the text.

> A simple MEDLINE search reveals that the levels of
> formaldehyde they are talking about (30 micrograms after the
> ingestion of 200 mg/kg/day of aspartame for 11 days) are
> well within 'safe' levels, even though 200 mg/kg is equal to
> about 60 Diet Cokes per day(!).

The truth is that there is no MEDLINE summary showing an exposure to or an accumulation of 30 micrograms (ug) of formaldehyde in humans after ingestion of 200 mg/kg/day of aspartame. This figure appears to be either fabricated or caused by some serious math errors. The actual figure can be calculated quite easily and is approximately 61.3 milligrams (mg) for ingestion of one liter of diet soda.

The actual measured amount of aspartame in one liter of diet soda is approximately 600 mg. [Ref. 1]. If a 60 kg (132 lbs) woman ingested one liter of diet soda, she would be ingesting 10 mg/kg of aspartame:

Aspartame breaks down into 10.9% methanol by weight [Ref. 2]. So that the amount of methanol obtained from 600 mg of aspartame is:

Methanol converts to formaldehyde in the body. [Note: Methanol from fruit and alcoholic beverages does not convert to formaldehyde because of protective factors/chemicals in the foods. See:] Methanol [CH(3)OH] has a molecular weight of approximately 32.0. Formaldehyde [HCHO] has a molecular weight of approximately 30.0. Therefore, 65.4 mg of methanol converts to:

If we had used a dose mentioned by the author in the industry public relations (PR) article of 200 mg/kg instead of an easily-obtainable dose of 10 mg/kg, the formaldehyde exposure would be 20 times greater or 1,226 mg of formaldehyde. If we used the length of exposure mentioned in this PR article of 11 days, the exposure to formaldehyde would be a further 11 times greater or 1,226 * 11 = 13,486 mg of formaldehyde.

The author of the PR article was off by a factor of:

Some scientists might argue that only 70 - 75% of the methanol from aspartame is absorbed and of that amount, approximately 90% is converted into formaldehyde during the metabolic process [Ref. 3]. Even if true, it is clear that the exposure to formaldehyde is somewhere from 283,000 to 449,533 times what was mentioned in the PR piece. Using these figures, the exposure to formaldehyde from a 600 mg dose of aspartame would be:

Rather than discussing an unobtainable daily dose of 200 mg/kg, it is preferable to discuss a very easily obtainable dose of 10 mg/kg of aspartame. Actually, a large number of people have reported to this author ingesting far in excess of this amount on a daily basis. Even the industry's own research shows that higher dosages are easily-obtainable by consumers [Ref. 4].

An exposure to a daily dose of 40.0 mg to 61.3 mg of formaldehyde is clearly enough to cause gradual damage (without even considering aspartame's excitotoxin that would likely worsen the damage as discussed at:

The daily dose of airborne formaldehyde exposure that was shown to cause irreversible genetic damage [Ref. 5] was:

The genetic damage from formaldehyde exposure at approximately 33.75 mg/day was seen after many years of exposure. The longer the exposure, the more genetic damage.

It is important to keep in mind that the health effects of methanol are different in humans as compared to rodents and non-human primates [Ref. 6], so experiments of the health effects of aspartame in rodents and non-human primates might not apply readily to health effects in humans. Methanol is many times more toxic to humans than to rodents.

Exposure to formaldehyde at levels much lower than the 33.75 mg per day (that causes irreversible genetic damage) has been shown to cause musculoskeletal problems, cardiovascular symptoms, gastrointestinal problems, and a wide range of other chronic toxicity symptoms. Formaldehyde exposure, especially in the presence of co-exposure to an excitotoxin from aspartame appears to cause gradual neurological damage and immunological system changes. Please see discussions at both: and for details and scientific references related methanol and formaldehyde toxicity.

The study by Trocho et al. [Ref. 7] showed that exposure to a single dose of 20 mg/kg of aspartame (or a chronic dose of 200 mg/kg) led to the accumulation of formaldehyde in the body. The accumulation of formaldehyde was seen throughout the body, in the organs (liver, kidneys, brain) and tissues. (See: The level of formaldehyde accumulation was calculated by Trocho et al. to be from 5% of the total methanol levels of aspartame given. For every 600 mg of aspartame (a 10 mg/kg dose in a 60 kg woman), the amount of formaldehyde estimated to accumulate is:

The research on formaldehyde toxicity and damage is based upon exposure only. If formaldehyde from aspartame accumulates in organs and tissues as the Trocho et al. experiment appears to demonstrate, then it is like a ticking time bomb for those who ingest aspartame (even if they have not yet experienced symptoms).

> Well, this published MEDLINE study states that the safe level
> of formaldehyde consumption for humans is 3 mg/kg/day. So
> someone who weighs 70kg (154 pounds) can safely
> consume 70 x 3 = 210 milligrams of formaldehyde per day.

This is a complete misrepresentation of the formaldehyde research. Formaldehyde is not readily abosrbed from foods [Ref. 8]. But the methanol in aspartame is readily and quickly absorbed and then converted into formaldehyde once in the body [Ref. 9, Ref. 10]. (Methanol in fruits has protective factors/chemicals to prevent conversion into formaldehyde.)

Therefore, any comparison to formaldehyde in foods, is useless. A closer comparison (but still not ideal) is a comparison to the inhalation toxicity of formaldehyde since formaldehyde is easily introduced into the bloodstream through inhalation or from methanol derived from aspartame ingestion. The toxicity differences between inhalation of formaldehyde and formaldehyde derived from aspartame appear to relate to:

  1. Aspartame also breaks down into an excitotoxin that would be expected to increase the toxicity of the formaldehyde and its metabolite, formic acid. Please see discussions at both: and

  2. Inhalation exposure to formaldehyde likely leads to a greater exposure of formaldehyde to organs other than the liver. But the Trocho et al study makes it clear that at least some of the formaldehyde derived from aspartame is distributed to other organs and tissues.

To conclude, the 30 microgram figure was obviously off by a factor of over 400,000. The amount of formaldehyde exposure is more than what has been seen to cause chronic toxicity in independent formaldehyde exposure research. When one considers 1) the total formaldehyde exposure, 2) the long term exposure to and accumulation of formaldehyde, 3) the excitotoxin obtained from aspartame that would likely increase the toxicity of the formaldehyde, 4) the permanent damage that can result from chronic formaldehyde poisoning, 5) the huge numbers of people reporting serious health problems from long-term aspartame use (, and 6) the fact that independent controlled human studies nearly always find problems with aspartame (even though the experiments are quite short), it is a good idea to avoid any aspartame ingestion.


Tsang, Wing-Sum, et al., 1985. "Determination of Aspartame and Its Breakdown Products in Soft Drinks by Reverse- Phase Chromatography with UV Detection," Journal Agriculture and Food Chemistry, Vol. 33, No. 4, page 734-738.

Aspartame is composed of: C(14) O(5) N(2) H(18) [See Journal of AOAC International, Volume 76, No. 2, 1993: "Determination of Aspartame and Its Major Decomposition Products in Foods."]

The molecular weights are:
The total molecular weight of methanol is approximately 32.0 as described above. Therefore, aspartame breaks down into:

Kavet, Robert, Kathleen M. Nauss, 1990. "The Toxicity of Inhaled Methanol Vapors," Critical Reviews in Toxicology, Volume 21, Issue 1, page 21-50.

Porikos, Katherine P., Theodore B. Van Italie, 1984. "Efficacy of Low-Calorie Sweeteners in Reducing Food Intake: Studies with Aspartame" IN Stegink, L., Filer L., 1984. "Aspartame: Physiology and Biochemistry," Marcel Dekker, Inc., N.Y., page 273-286.

Shaham, J., Y. Bomstein, A. Meltzer, Z. Kaufman, E. Palma, J. Ribak, 1996. "DNA--protein Crosslinks, a Biomarker of Exposure to Formaldehyde--in vitro and in vivo Studies," Carcinogenesis, Volume 17, No. 1, page 121-125.

Roe, O., 1982. "Species Differences in Mehtanol Poisoning," CRC Critical Reviews In Toxicology, October 1982, page 275-286.

Trocho, C., et al., 1998. "Formaldehyde Derived From Dietary Aspartame Binds to Tissue Components in vivo," Life Sciences, Vol. 63, No. 5, pp. 337+, 1998

Restani, Patrizia, Corrado Galli, 1991. "Oral Toxicity of Formaldehyde and Its Derivatives," Critical Reviews in Toxicology, Volume 21, Issue 5, pages 315-328.

Haggard, H., L. Greenberg, 1939. "Studies in the absorption, distribution and elimination of alcohol IV. The elimination of methyl alcohol," Journal of Pharmacology and Experimental Therap., Volume 66, pages 479-496.

Stegink, Lewis, 1984. "Aspartame Metabolism in Humans: Acute Dosing Studies," IN Stegink, L., Filer L., 1984. "Aspartame: Physiology and Biochemistry," Marcel Dekker, Inc., N.Y., page 509-553.