Friday, November 6, 2009

Formaldehyde: Carcinogen in Vaccinations

Formaldehyde: carcinogen

The Agency for Toxic Substances and Disease Registry: the CDC's own information on the substance:

Formaldehyde is synthesized by the oxidation of methanol. It is among the 25 most abundantly produced chemicals in the world and is used in the manufacture of plastics, resins, and urea-formaldehyde foam insulation. Formaldehyde or formaldehyde-containing resins are used in the manufacture of chelating agents, a wide variety of organic products, glass mirrors, explosives, artificial silk, and dyes. It has been used as a disinfectant, germicide, and in embalming fluid. In the agricultural industry, formaldehyde has been used as a fumigant, preventative for mildew in wheat and rot in oats, a germicide and fungicide for plants, an insecticide, and in the manufacture of slow-release fertilizers. Formaldehyde is found in construction materials such as plywood adhesives.

Health Effects

Formaldehyde is an eye, skin, and respiratory tract irritant.

Children may be more susceptible than adults to the respiratory effects of formaldehyde.

Formaldehyde solution (formalin) causes corrosive injury to the gastrointestinal tract, especially the pharynx, epiglottis, esophagus, and stomach.

The systemic effects of formaldehyde are due primarily to its metabolic conversion to formate, and may include metabolic acidosis, circulatory shock, respiratory insufficiency, and acute renal failure.

Formaldehyde is a potent sensitizer and a probable human carcinogen.

Formaldehyde vapor produces immediate local irritation in mucous membranes, including eyes, nose, and upper respiratory tract.

Ingestion of formalin causes severe injury to the gastrointestinal tract.

The exact mechanism of action of formaldehyde toxicity is not clear, but it is known that it can interact with molecules on cell membranes and in body tissues and fluids (e.g., proteins and DNA) and disrupt cellular functions.

High concentrations cause precipitation of proteins, which results in cell death. Absorption from the respiratory tract is very rapid; absorption from the gastrointestinal tract is also rapid, but may be delayed by ingestion with food. Once absorbed, formaldehyde is metabolized to formic acid, which may cause acid-base imbalance and a number of other systemic effects.


Accumulation of formic acid can cause an anion-gap acid-base imbalance. If formalin is ingested, absorption of the methanol stabilizer may contribute to the imbalance and can result in an osmolal gap, as well as an anion gap.


In persons who have been previously sensitized, inhalation and skin contact may cause various skin disorders, asthma-like symptoms, anaphylactic reactions and, rarely, hemolysis. The immune system in children continues to develop after birth, and thus, children may be more susceptible to certain chemicals.


Ingestion of aqueous solutions of formaldehyde can result in severe corrosive injury to the esophagus and stomach. Nausea, vomiting, diarrhea, abdominal pain, inflammation of the stomach, and ulceration and perforation of the oropharynx, epiglottis, esophagus, and stomach may occur. Both formaldehyde and the methanol stabilizer are easily absorbed and can contribute to systemic toxicity.

Formaldehyde and cancer: current evidence and future perspectives

Can formaldehyde cause cancer?

Although the short-term health effects of formaldehyde exposure are well known, less is known about its potential long-term health effects. In 1980, laboratory studies showed that exposure to formaldehyde could cause nasal cancer in rats. This finding raised the question of whether formaldehyde exposure could also cause cancer in humans. In 1987, the U.S. Environmental Protection Agency (EPA) classified formaldehyde as a probable human carcinogen under conditions of unusually high or prolonged exposure (1). Since that time, some studies of industrial workers have suggested that formaldehyde exposure is associated with nasal sinus cancer and nasopharyngeal cancer, and possibly with leukemia. In 1995, the International Agency for Research on Cancer (IARC) concluded that formaldehyde is a probable human carcinogen. In June 2004, after evaluating all existing data, the IARC reclassified formaldehyde as a known human carcinogen (2).

Several NCI studies have found that anatomists and embalmers, people who are potentially exposed to formaldehyde in their professions, are at an increased risk of leukemia and brain cancer compared with the general population. In 2003, a number of cohort studies were completed among workers exposed to formaldehyde. One study, conducted by NCI, looked at 25,619 workers in industries with the potential for occupational formaldehyde exposure and estimated each worker’s exposure to the chemical while at work (3). The results showed an increased risk of death due to leukemia, particularly myeloid leukemia, among workers exposed to formaldehyde. This risk was associated with increasing peak and average levels of exposure, as well as with the duration of exposure, but not with cumulative exposure. Using an additional 10 years of data, a follow-up study published in 2009 continued to show a possible link between formaldehyde exposure and cancers of the hematopoietic and lymphatic systems, particularly myeloid leukemia, as was previously reported (4). As in the previous study, the risk was highest earlier in the follow-up period and declined steadily over time, such that the cumulative excess risk of myeloid leukemia was no longer statistically significant. The researchers noted that similar patterns of risks over time had been seen for other agents known to cause leukemia.
A separate study of 11,039 textile workers performed by the National Institute for Occupational Safety and Health (NIOSH) also found an association between the duration of exposure to formaldehyde and leukemia deaths (5).

Formaldehyde undergoes rapid chemical changes immediately after absorption. Therefore, some scientists think that formaldehyde is unlikely to have effects at sites other than the upper respiratory tract. However, some laboratory studies suggest that formaldehyde may affect the lymphatic and hematopoietic systems. Based on both the epidemiologic data from cohort studies and the experimental data from laboratory research, NCI investigators have concluded that exposure to formaldehyde may cause leukemia, particularly myeloid leukemia, in humans. However, inconsistent results from other studies suggest that further research is needed before definite conclusions can be drawn.

Selected References

1 U.S. Environmental Protection Agency, Office of Air and Radiation. Report to Congress on Indoor Air Quality, Volume II: Assessment and Control of Indoor Air Pollution, 1989.
2 International Agency for Research on Cancer (June 2004). IARC Monographs on the Evaluation of Carcinogenic Risks to Humans Volume 88 (2006): Formaldehyde, 2-Butoxyethanol and 1-tert-Butoxypropan-2-ol. Retrieved May 4, 2009, from:
5 Pinkerton LE, Hein MJ, Stayner LT. Mortality among a cohort of garment workers exposed to formaldehyde: An update. Occupational Environmental Medicine 2004; 61:193–200.

(pgs 57-62 for cancer related charts)

Studies on formaldehyde's causation as a carcinogen:

Zhang L, Freeman LE, Formaldehyde and leukemia: Epidemiology, potential mechanisms, and implications for risk assessment.Environ Mol Mutagen. 2009 Sep 29.

Excerpt: Here, we provide a summary of the symposium at the Environmental Mutagen Society Meeting in 2008, which focused on the epidemiology of formaldehyde and leukemia, potential mechanisms, and implication for risk assessment, with emphasis on future directions in multidisciplinary formaldehyde research. Updated results of two of the three largest industrial cohort studies of formaldehyde-exposed workers have shown positive associations with leukemia, particularly myeloid leukemia, and a recent meta-analysis of studies to date supports this association. Recent mechanistic studies have shown the formation of formaldehyde-induced DNA adducts and characterized the essential DNA repair pathways that mitigate formaldehyde toxicity.

Hauptmann M, Lubin JH, Mortality from lymphohematopoietic malignancies among workers in formaldehyde industries. J Natl Cancer Inst. 2003 Nov 5;95(21):1615-23.

Feron VJ, Til HP, Formaldehyde must be considered a multipotential experimental carcinogen.Toxicol Ind Health. 1990 Dec;6(6):637-9.

Soffritti M, Belpoggi F, Results of long-term experimental studies on the carcinogenicity of formaldehyde and acetaldehyde in rats.Ann N Y Acad Sci. 2002 Dec;982:87-105.

Soffritti M, Maltoni C, Formaldehyde: an experimental multipotential carcinogen. Toxicol Ind Health. 1989 Oct;5(5):699-730.

Excerpt: The experimental results presented in this report give scientific support to the epidemiological observation of a higher incidence of leukemias and of gastro-intestinal cancers among the people occupationally exposed.

Blackwell M, Kang H, Formaldehyde: evidence of carcinogenicity.Am Ind Hyg Assoc J. 1981 Jul;42(7):A34, A36, A38, passim.

Shaham J, Bomstein Y, DNA--protein crosslinks, a biomarker of exposure to formaldehyde--in vitro and in vivo studies. Carcinogenesis. 1996 Jan;17(1):121-5.

Excerpt: Formaldehyde (FA) is a widely produced industrial chemical. Sufficient evidence exists to consider FA as an animal carcinogen. In humans the evidence is not conclusive. DNA-protein crosslinks (DPC) may be one of the early lesions in the carcinogenesis process in cells following exposures to carcinogens... We conclude that our data indicate a possible mechanism of FA carcinogenicity in humans and that DPC can be used as a method for biological monitoring of exposure to FA.

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