Association of Formaldehyde Exposure to Myeloid Leukemia in Workers in Guangdong, China
Condition: Epidemiology; Industrial Hygiene; Neoplasms
Study type: Observational

Summary: 
      Background:

        -  Research suggests that occupational exposure to formaldehyde is associated with
           increased risk for myeloid leukemia, but the significance of these findings is uncertain
           because of inconsistencies among studies and lack of knowledge of how formaldehyde can
           cause leukemia.

        -  Damage to the DNA of myeloid cells (type of white blood cell) or an environmental factor
           not affecting the cell genetic machinery may be involved.

      Objective: To determine if formaldehyde exposure is associated with genetic or other changes
      in myeloid cells.

      Eligibility: Workers exposed to high levels of formaldehyde and unexposed workers in
      Guangdong Province, China.

      Design:

        -  40 exposed workers and 40 unexposed workers will be enrolled.

        -  Subjects wear small instruments at work that measure chemicals in the air for 1 or 2
           days.

        -  Subjects have a brief physical examination and provide blood, urine, and mouth rinse
           samples.

        -  Subjects answer a questionnaire about work, smoking and drinking, use of medicines,
           medical history, general health, exposure to radiation and exposure to various
           substances at home.
    

Detailed description: 
      Research in industrial workers and professionals exposed to formaldehyde suggests that
      occupational exposure to this important chemical is associated with increased risk for
      myeloid leukemia. The significance, however, of these observations for occupational and
      environmental health is uncertain because of inconsistencies among epidemiologic studies and
      lack of a demonstrated mechanism through which formaldehyde can cause leukemia. Cytogenetic
      damage is one potential leukemogenic mechanism, but there are few studies of
      formaldehyde-exposed humans. Some experimental data suggest that epigenetic changes in
      myeloid cells could also be involved. We plan to study 40 workers exposed to high levels of
      formaldehyde and 40 unexposed controls to examine the hypothesis that formaldehyde is
      associated with these changes. To determine formaldehyde exposure, we will incorporate a
      number of methods, including questionnaires to determine potential past exposure and on-site
      monitoring to determine current average and peak intensities of exposure. We will then
      examine differences in aneuploidy and structural abnormalities in myeloid progenitor cells
      cultured from peripheral blood. We will specifically look for differences in genes associated
      with myeloid leukemia such as monosomy 7 and trisomy 8 using interphase and Octochrome FISH.
      We will also determine whether aberrant methylation in progenitor cells, specifically
      hypermethylation of genes associated with myeloid leukemia, is higher in those exposed to
      formaldehyde. This study will substantially contribute to our understanding of the
      leukemogenic potential of formaldehyde, which has important public health and regulatory
      implications.
    

Observational model: Other
Time perspective: Cross-Sectional
Sampling method: Probability Sample
Study population: 
        We identified one factory that produced formaldehyde-melamine resins and one factory that
        used formaldehyde-melamine resins to manufacture plastic utensils. Monitoring of
        formaldehyde levels was performed in these factories during an initial screening and it was
        established that there were no other exposures to known or suspected leukemogens or
        hematotoxicants (e.g., benzene, phenol, chlorinated solvents). We selected a control
        population from three workplaces in the same @@@geographic region as factories with
        formaldehyde exposure and enrolled workers who had comparable demographic and socioeconomic
        characteristics and who were engaged primarily in manufacturing. Detailed inspection of the
        control workplaces did not identify potential for occupational exposure to formaldehyde or
        any other@@@hematotoxic or genotoxic chemicals in excess of exposure levels in the general
        population.
      
Keywords: Industry Hygiene; Molecular Epidemiology; Cancer Susceptability; Genotoxocity; FISH