THE ROLE OF COMBINATION EFFECTS ON THE ETIOLOGY OF MALIGNANT NASAL TUMORS IN THE WOOD-WORKING INDUSTRY - MOST RECENT FINDINGS AND ANALYSIS OF 147 INDEMNIFIED CASES OF ADENOCARCINOMAS

Adenocarcinomas of the nose are regarded as an occupational disease in Germany and other European countries, and workers exposed to oak or b eech wood-dust in the course of their work receive compensation if the y incur adenocarcinoma of the nose. This has prompted a joint research project to record the functional and morphological changes of the nas al mucosa and/or paranasal sinus of 149 exposed subjects and 33 contro ls in accordance with a defined occupational exposure. To ensure the q uantitative and qualitative reliability of the exposure data, 1,349 me asurements at the company workplace were taken and analyses of 614 woo d samples performed; parallel to this, the genotoxic effects of the mo st important substances used in the wood-working industry were tested. Apart from this, latency periods and morbidity rates in Germany were investigated. Partial findings of this research projects have been eva luated by the International Agency for Research on Cancer (IARC). Acco rding to these evaluations and the findings presented here, the follow ing points can be made: i) Morphological changes in the nasal mucosa a fter exposure to wood-dust resulted in an increase in cylindrocellular hyperplasias and, in functional terms, a tendency towards improved na sal clearance was observed. Chromium and Formaldehyde, on the other ha nd, tended to give rise to an increase in the number of squamous metap lasias. This might explain the preference for the histological types o f adenocarcinoma among subjects exposed to wood-dust. ii) In tissue sa mples more dysplasias were found among those exposed to oak and beech wood-dust. Subjects exposed to wood preserving agents had dysplasias o nly if they were simultaneously exposed to oak and beech wood-dust. Th e latter effect did not quite reach the level of significance (p = 0.0 7) on account of the low numbers of cases, iii) The investigation of g enotoxic effects showed that oak and beech contain genotoxic substance s that can be dissolved by means of ethanol and cyclohexane; they also showed that 3 out of 8 wood preservatives, 5 out of 16 stains, and 2 out of 11 paints from the wood-working industry are genotoxic too. Apa rt from this, lindane and PCP have proved to be genotoxic in the nasal cells of rats and human beings. Analysis of 614 wood samples from woo d-preserving agents showed that almost 73% contained agents of this ty pe, even in woods described by the companies as being guaranteed free of wood preservatives. iv) According to an analysis of 147 cases accep ted since 1985 as a pensionable occupational illness by the Holz-Beruf sgenossenschaft (an industrial compensation society for employees in t he wood-working industry), the disease was much more apparent in small companies where there is multi-factorial exposure, than in large comp anies where the exposure factor tends to have a single component. This points to the combined effects of hardwood dusts and chemicals as bei ng the cause, v) According to published findings, the incidence of the disease in England seems to be on the decline. In Germany, increasing latency; periods also point to a decline in the number of cases, alth ough both countries have only very recently introduced effective preve ntion measures against exposure to wood-dust. This also leads to the a ssumption that wood-dusts cannot be the only cause of this type of can cer. vi) These findings tally with the evaluation by the IARC confirmi ng the special part that hardwood dusts play in the development of nas al cancer. The findings presented here also indicate combined effects as being the cause of this type of cancer. This hypothesis cannot be c onfirmed until the conclusion of long-term animal experiments, current ly being conducted, to test how the effects of chemicals such as linda ne, PCP, and chromate compare with use of oak wood-dust.