BackgroundThe aim of the study was to investigate whether exposure to formaldehyde, organic solvents or other chemicals in the wood-processing industry affects the fertility of women. Methods For this purpose, a retrospective study on time to pregnancy was conducted among female wood workers who had given birth during 1985-1995. Data on pregnancy history, time to pregnancy, occupational exposures, and potential confounders were collected by a questionnaire; 64% (699/1,094) participated. The exposure assessment was conducted by an occupational hygienist. The data on time to pregnancy were analyzed with the discrete proportional hazards regression. Results Exposure to formaldehyde was significantly associated with delayed conception: adjusted fecundability density ratio, FDR, was 0.64 (95% CI 0.43-0.92). At high exposure if no gloves were used, the FDR was 0.51 (% CI 0.28-0.92). Exposure to phenols, dusts, wood dusts, or organic solvents was not related to the time to pregnancy. Additionally, an association was observed between exposure to formaldehyde and an increased risk of spontaneous abortion (concerning previous spontaneous abortions, reported by the women). Associations between exposure to formaldehyde or to organic solvents and endometriosis, and between exposure to organic solvents or to dusts and salpingo-oophoritis were also suggested. ConclusionsThe study suggests that a woman's occupational exposure to formaldehyde has an adverse effect on fertility.

As part of an International Agency for Research on Cancer (IARC) international epidemiological study of workers in the pulp and paper industry, previously unpublished exposure measurements were assembled in a database. This article summarizes the results of 3,873 measurements carried out in the production departments of paper and paperboard mills and recycling plants in 12 countries. In the paper and paperboard mills, most of the agents were measured in the pulping and refining departments and in on-machine coating and winding of paper/paperboard. Exposures to asbestos, carbon monoxide, formaldehyde, fungal spores, bacteria, nitrogen dioxide, minerals dusts, paper dust, sulphuric acid and different solvents sometimes exceeded exposure limit values. In the re-pulping and de-inking departments of recycling plants high exposures to formaldehyde, fungal spores, bacteria and paper dust were observed. High exposures to asbestos, bioaerosols, carbon monoxide and paper dust were found in many departments; ammonia, formaldehyde, mineral and paper dust and solvents were found in coating machines; and diphenyl and polychlorobiphenyls (PCBs) were found in some special circumstances. Measurements in the newsprint and uncoated paper machine departments revealed only a few elevated exposures. In nearly all departments, measurements of epichlorohydrin, PCBs, sulphur dioxide, hydrogen sulphide and mercaptans tended to be low, often even below their detection limits. In spite of some uncertainties in the measurement data, the study provides new insights into the level and variation of occupational exposures of production workers in the paper and paperboard industry.

The highest monoterpene concentration (GM), in the breathing zone, measured during processing of pine, was less than one-fourth of the Finnish occupational exposure limit (OEL, 570 mg/m(3)). Verbenol concentrations in postshift urine samples reflected accurately the exposure to monoterpenes. The concentrations of inhalable dust (GM) were less than one-half the Finnish OEL (5 mg/m(3)). No significant differences in dust exposure were observed among tree species processed. Work-related symptoms appeared to correlate with monoterpene exposure during processing of pine and with wood dust exposure during processing of spruce.

A data management system and a department-exposure matrix (PAPDEM) was designed and constructed to facilitate exposure assessment for a large multinational study on cancer risks among pulp, paper, and paper product workers. Exposure to 25 major agents was described by prevalence, P (i.e., proportion of the exposed, classified %-range), and level, L (i.e., annual mean concentration at work, classified). Some agents could be assessed only in qualitative terms. The assessment was specific to mill, work department, agent, and time period. The results of industrial hygiene measurements, information from detailed company questionnaires, and the professional judgments of the assessment team were the cornerstones of the assessment. Validity and consistency of the assessment were aimed at by setting default values for P and L prior to the assessment, accurately defining agents and exposure classes, dividing assessment work by subindustry, working in pairs, testing interrater agreement, and finalizing the estimates in a meeting. In spite of these precautions, good agreement between different assessors was difficult to reach. Exposure to chemical agents turned out to be widespread and complex with frequent multiple exposures. A computer-assisted exposure assessment system such as PAPDEM may save time and facilitate assessment in large epidemiological studies requiring complicated exposure assessment procedures. It also provides a good documentation of exposure assignments, which may be useful in the interpretation of the results and in future updates of the study.

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