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Health Concerns

Acetaldehyde Formaldehyde

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Formaldehyde

The primary way formaldehyde may enter the body is by inhalation of contaminated air. Experimental studies indicate that most of the formaldehyde inhaled into the lungs is rapidly broken down into other compounds (metabolized) at the site of contact and quickly absorbed into the body through the lining of the nose or from the upper part of the lungs (ATSDR, 1997). Due to this rapid local metabolism, inhalation exposure to even moderately high ambient concentrations of this compound has not been found to effect the amount of formaldehyde present in the blood. In fact, rapid local metabolism is why "... little if any intact formaldehyde can be found in the blood..." at any time (ATSDR, 1997). Rapid local metabolism also results in toxicity primarily at the site of contact.

Formaldehyde is a normal metabolic product of animal cell metabolism. Thus, almost all the tissues in the body are able to metabolize this compound. Formaldehyde is primarily metabolized to formate which can be incorporated into other essential molecules or pass from the body in the urine or be further metabolized to carbon dioxide which leaves the body in exhaled air. If metabolism to formate is inhibited or the metabolic mechanism overloaded, internal levels of formaldehyde may increase to the point where it can form bonds between proteins or between proteins and deoxyribonucleic acid (DNA). Formaldehyde and formate are both part of routine animal cell metabolic processes and neither is stored to any extent in the body (ATSDR, 1997).

Inhalation of ambient levels of formaldehyde vapors between .4 and 3 ppm (490 ug/m 3 to 3700 ug/m 3 ), even for short periods of time, can irritate the eyes, nose, and throat and cause increased tearing and itching. Upper respiratory tract symptoms are believed to predominate because rapid local metabolism may prevent much formaldehyde from reaching the lower respiratory tract (ATSDR, 1997). Some studies indicate that long-term exposure to similar levels might adversely impact respiratory function while other studies do not support this contention. Short-term exposure to very high ambient levels may result in coughing wheezing, chest pains and bronchitis.

Some people are known to be more sensitive to formaldehyde than others and repeated exposure, including via inhalation of vapors, is believed to cause an increase in sensitivity in some individuals. Although one large study suggests that those with asthma may be particularly sensitive to formaldehyde vapors, many other studies have not made this finding.

Experimental studies with laboratory rats have found that long-term inhalation of highly elevated ambient levels of formaldehyde can cause nasal cancer (squamous cell carcinoma) in the rats. There is limited evidence that long-term inhalation of low levels of this compound might be associated with an increase in cancer in humans (ATSDR, 1997).

Formaldehyde has been shown to be a contact irritant, regardless of the route of exposure. Limited studies indicate that formaldehyde is rapidly absorbed from the gastrointestinal tract and meets the same metabolic fate as inhaled formaldehyde vapors (ATSDR, 1997). Ingestion of elevated amounts of this compound can irritate the mouth, esophagus and gastric mucosa (ATSDR, 19997). Lesions of the gastric mucosa have been noted in laboratory animals experimentally exposed to formaldehyde in drinking water for various periods of time. Human consumption of very large amounts of formaldehyde (i.e., suicide attempts) can result in severe abdominal pain, acidosis, central nervous system depression, coma and death (ATSDR, 1997).

Two studies indicate that an increase in the amount of formaldehyde in the diet of some milk producing animals such as cows, sheep and goats, can increase the amount of formaldehyde present in the milk produced. The reason for this is not clear. However, it is postulated that perhaps fundamental differences exist between the way humans and ruminants metabolize formaldehyde.

Although very small amounts of formaldehyde can be absorbed into the body through intact skin, dermal contact with this compound can result in sensitization. Dermal contact with liquid formaldehyde can irritate the skin. Allergic reactions of the skin and in extreme cases, anaphylaxis are reported in the literature (ATSDR, 1997).

Formaldehyde has been classified as Class B1: Probable Human Carcinogen by the United States Environmental Protection Agency and as a Group 2A: Probable Human Carcinogen by the International Agency for Research on Cancer.

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Last Updated: 1/31/03

 

   
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