Historical Cohort Study of US Man-Made Vitreous Fiber Production Workers: I. 1992 Fiberglass Cohort Follow-Up: Initial Findings

Abstract

This 1986 to 1992 update and expansion of an earlier historical cohort study examined the 1946 to 1992 mortality experience of 32,110 workers employed for 1 year or more during 1945 to 1978 at any of 10 US fiberglass (FG) manufacturing plants. Included are (1) a new historical exposure reconstruction for respirable glass fibers and several co-exposures (arsenic, asbestos, asphalt, epoxy, formaldehyde, polycyclic aromatic hydrocarbons, phenolics, silica, styrene, and urea); and (2) a nested, matched case-control study of 631 respiratory system cancer (RSC) deaths in male workers during 1970 to 1992 with interview data on tobacco smoking history. Our findings to date from external comparisons based on standardized mortality ratios (SMRs) in the cohort study provide no evidence of excess mortality risk from all causes combined, all cancers combined, and non-malignant respiratory disease. Also, excluding RSC, we observed no evidence of excess mortality risk from any of the other cause-of-death categories considered. For RSC among the total cohort, we observed a 6% excess (P = 0.05) based on 874 deaths. Among long-term workers (5 or more years of employment) we observed a not statistically significant 3% excess based on 496 deaths. Among the total cohort, we observed increases in RSC SMRs with calendar time and time since first employment, but these were less pronounced among long-term workers. RSC SMRs were not related to duration of employment among the total cohort or long-term workers. In an externally controlled analysis of male workers at risk between 1970 and 1992, we observed no association between RSC SMRs and increasing exposure to respirable FG. Our findings to date from internal comparisons based on rate ratios in the case-control study of RSC were limited to analyses of categorized study variables with and without adjustment for smoking. On the basis of these analyses, the duration of exposure and cumulative exposure to respirable FG at the levels encountered at the study plants did not appear to be associated with an increased risk of RSC. RSC risk also did not seem to increase with time since first employment. There is some evidence of elevated RSC risk associated with non-baseline levels of average intensity of exposure to respirable glass, but when adjusted for smoking this was not statistically significant, and there was no apparent trend with increasing exposure. This same pattern of findings was observed for duration of exposure, cumulative exposure, and average intensity of exposure to formaldehyde. None of the other individual co-exposures encountered in the study plants appeared to be associated with an increased risk of RSC. The primary focus of ongoing analyses is to determine the extent to which our present findings are robust to alternative characterizations of exposure.

Reevaluation of mortality risks from nasopharyngeal cancer in the formaldehyde cohort study of the National Cancer Institute

“…However, evidence exists that some workers from at least one of the 10 NCI formaldehyde plants (Plant 1) had possible occupational or non-occupational exposures to potential NPC risk factors outside of the plant (Marsh et al, 1996(Marsh et al, , 2002). Moreover, our experience with other multi-plant studies, such as our study of man-made mineral Wber workers (Marsh et al, 2001a) and our reanalysis of the NCI cohort study of acrylonitrileexposed workers (Marsh et al, 2001b) has found that one or more sites with unique confounding exposures are heavily inXuencing the exposure-response analysis. When such plant-speciWc, potential confounding exposures are present, a detailed evaluation of single plants is essential to a full understanding of the exposure-response relationship (or lack thereof) in question, and hence, was a major focus of our reanalysis.…”

Manejo de la fibra de vidrio en entorno laboral, potenciales efectos sobre la salud y medidas de control (Revisión)

“…Tampoco encontraron relación con el tiempo de exposición ni con el periodo de latencia, incluso pudieron observar que los trabajadores con un tiempo de exposición menor presentaban mayor riesgo de padecer un cáncer de pulmón que los que se habían encontrado expuestos a periodos más prolongados 38 . Este mismo autor realizó en 2001 un estudio de casos y controles sobre una población americana perteneciente a diez industrias relacionadas con la producción de FMA para estudiar el riesgo de desarrollar un cáncer de pulmón, sin que se obtuvieran incrementos significativos de este tipo de tumores en la población expuesta.…”

An Assessment of the Possible Extent of Confounding in Epidemiological Studies of Lung Cancer Risk Among Roofers

“…The PubMed search of asphalt workers resulted in more than 20 cohort studies (some with overlapping populations), (10,28,(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45)(46)(47)(48)(49)(50)68,69) 11 case-control studies, (51)(52)(53)(54)(55)(56)(57)(58)(59)(60)(61) and 7 proportionate mortality studies. (2,(62)(63)(64)(65)(66)(67) From this group of peer-reviewed epidemiological studies, the subset that specifically included roofers was identified, and the abstracted characteristics are presented by study type in Table I.…”