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DNA damage & formaldehyde exposure

Formaldehyde is a commonly used chemical in anatomy and pathology laboratories as a tissue preservative and fixative. Because of its sensitising properties, irritating effects and cancer implication, formaldehyde accounts probably for the most important chemical-exposure hazard concerning this professional group.

Researchers from Portugal and Spain have been investigating occupational exposure to formaldehyde using the comet assay.  For a full list of the author’s affiliations, please refer to the original publication











The researchers conducted a literature review and concluded that evidence for genotoxic effects and carcinogenic properties of formaldehyde in humans is insufficient and conflicting. They were particularly interested in the ability of inhaled formaldehyde to induce toxicity on other cells besides first contact tissues, such as buccal and nasal cells, but found that this is currently a subject with limited information. 

To evaluate the effects of exposure to formaldehyde in human peripheral blood lymphocytes, a group of 84 anatomy pathology laboratory workers exposed occupationally to formaldehyde and 87 control subjects were tested for chromosomal aberrations and DNA damage (comet assay). The level of exposure to formaldehyde in the workplace air was evaluated. During this investigation, the estimated mean level of formaldehyde exposure was 0.38±0.03 ppm.

The alkaline comet assay was performed with minor modifications and you may access the full experimental information in the original publication. Two gels were prepared for each donor and a ‘blind’ scorer examined 50 randomly selected cells from each gel (100 cells/donor).  Microscopic analysis was performed on a Nikon Eclipse E400 Epi-fluorescence microscope. Image capture and analysis was performed with Comet Assay IV software (Perceptive Instruments). The percentage of DNA in the comet tail (%TDNA) was the DNA damage parameter evaluated.


The researchers concluded that all the cytogenetic endpoints (assessed by both the chromosome aberration test and comet assay % tail DNA) were significantly higher in formaldehyde-exposed workers compared with controls. Data obtained in this study showed a potential “health risk situation” of anatomy pathology laboratory workers routinely exposed to formaldehyde. The researchers believe that implementation of security and hygiene measures, such as periodic air sampling and medical surveillance, as well as good practice campaigns, may be crucial to decrease this risk. The scientists involved in this study also believe that the conclusions established here may provide important data to be used by health care programs and governmental agencies responsible for occupational health and safety.

For more information on this study, please refer to the original article:

Increased levels of chromosomal aberrations and DNA damage in a group of workers exposed to formaldehyde

Solange Costa, Sandra Carvalho, Carla Costa, Patrícia Coelho,  Susana Silva, Luís S. Santos,  Jorge F. Gaspar,   Beatriz Porto, Blanca Laffon and João P. Teixeira. Mutagenesis, 2015, 1–11