CEFIC - formaldehyde sector group


health and safety

Inside buildings the persistence of formaldehyde in the air is low: the time needed for 50% of formaldehyde to disappear ("half-life") is less than 24 hours. This process can be accelerated by increasing sun radiation (for example in summer, middle of the day, etc). The half-life then falls to 2 hours. Indoors, the process can be increased dramatically by ensuring ventilation (e.g. by opening windows, doors etc). It is therefore very difficult for high levels of formaldehyde to accumulate.

The formaldehyde is transformed mainly into carbon monoxide and carbon dioxide.

The occupational health hazards of formaldehyde are mainly related to its irritant effects. It is irritant on inhalation, direct contact with skin or eyes and on ingestion.

Note that direct human exposure to high dosages is highly improbable because the odour is intolerable and the atmosphere unbreathable. 

Measures of formaldehyde exposure associated with nasopharyngeal cancer in the NCI study

 

Inhalation:

Formaldehyde vapour irritates the respiratory system. Individual sensitivity varies broadly, but irritancy can occur below 1 to 2 ppm (1 ppm = 1,2 mg/m³ at 25°C). Immediate strong discomfort is caused at a level of 10 ppm. Disorientation is possible.

Skin contact:

Formaldehyde solution is a moderate skin irritant and a repeated contact can cause hardening and cracking of skin. This may give rise to dermatitis. In addition there is a potential for skin sensitisation (allergy).

Eye contact:

Formaldehyde solution is a severe eye irritant. If it comes into contact with eyes, it may lead to permanent eye damage. Exposure to vapour or formaldehyde containing dust may cause inflammation of the eyelids.

Ingestion:

The swallowing of formaldehyde solution causes immediate irritation of the mouth, throat and stomach, resulting in nausea and vomiting. In extreme cases severe abdominal pain is experienced, possibly followed by loss of consciousness (by collapse).

  1. Formaldehyde is classified as a carcinogenic hazard. Two separate classifications have been published:
    International Agency for Research on Cancer (IARC) has classified formaldehyde as 1 ("carcinogenic to humans"). The latest review on this was done in June 2004 (see our press release). IARC is a non-regulatory body.
    This classification is based on relatively rare nasopharyngeal cancers observed in workers exposed to high levels of formaldehyde some decades ago. A large number of human studies have provided no convincing evidence that formaldehyde produces cancer in man. However, exposure at the workplace has to be kept as low as reasonably practicable. Compliance with workplace occupational limit values should minimise the risk to health from inhalation of formaldehyde.
  2. In the EU countries formaldehyde is classified according to the Dangerous Substances Directive as a category 3 (C3) carcinogen leading to a risk phrase R 40 (Limited evidence of a carcinogenic effect). This is the weakest class of carcinogenic hazard.


As with many other substances, there are indications that in the very unlikely event of prolonged exposure to very high emissions of formaldehyde one would encounter negative health effects, including possibly cancer.

 Formaldehyde thresholds in Europe (August 2005) 

Measures of formaldehyde exposure associated with nasopharyngeal cancer in the NCI study

(Hauptmann et al., 2004)

The exposure assessment in the NCI study (Hauptmann et al., 2004), which served as the basis for the IARC classification has been described as follows:
"Exposure to formaldehyde was estimated from work histories collected through 1980 on the basis of job titles, tasks, visits to the plants by study industrial hygienists, discussions with workers and plant managers, and monitoring data [not further characterized]... No measurements of peak exposures [generally < 15 minutes] were available in this study. Peak exposures were therefore estimated by an industrial hygienist from knowledge of the job tasks and a comparison with the 8-hour time-weighted average."
Thus – evaluation is based on retrospectively estimated exposures from 1934 to 1980. Workplace exposure measurements are rare. In particular, information on formaldehyde exposure after 1980 was not available.

Nevertheless, the authors of the study use the following four exposure measures:
• average intensity of exposure
• highest peak exposure
• cumulative exposure
• duration of exposure

They argue that relative risks for nasopharyngeal cancer increased with all of these measures. They use a test for trend (with categories of increasing exposure) the p-value of which is significant for highest peak and cumulative exposure only. Since there were only 9 cases of nasopharyngeal cancer (out of the total cohort of 25,619 workers; 2 of these cases not exposed to formaldehyde), misclassification of exposure of a single case would change the trend analysis considerably.
However, all 7 workers who were exposed to formaldehyde and died from nasopharyngeal cancer had been exposed to formaldehyde peaks >= 4.0 ppm; in addition, they had been exposed to particulates as well. Cumulative exposure >= 5.5 ppm-years was also associated with an increased relative risk of nasopharyngeal cancer; but all nasopharyngeal cancer cases with cumulative exposure >= 5.5 ppm-years had also peak exposures >=4.0 ppm.

The two other large recently published studies of formaldehyde-exposed workers (Coggon et al., 2003; Pinkerton et al., 2004) have not observed an increased risk of nasopharyngeal cancer.

Current workplace exposure limits are based on sensory irritation with TWA in most countries at or below 0.5 ppm, and they limit peak exposure to 1.0 ppm or less. If they are strictly observed, peak exposures of 4.0 ppm and more - the concentrations for which an increased risk of nasopharyngeal cancer has been observed in the NCI study - will not occur.

References:

Coggon D et al. Extended follow-up of a cohort of British chemical workers exposed to formaldehyde.
J Natl Cancer Inst 2003;95:1608-1615.

Hauptmann M et al. Mortality from solid cancers among workers in formaldehyde industries.
Am J Epidemiol 2004;159:1117-1130.

Pinkerton LE et al. Mortality among a cohort of garment workers exposed to formaldehyde: an update.
Occup Environ Med 2004;61:193-200.