Non-asbestiform elongate mineral particles and mesothelioma risk: Human and experimental evidence.

The presentations in this session of the Monticello II conference were aimed at summarizing what is known about asbestiform and non-asbestiform elongate mineral particles (EMPs) and mesothelioma risks based on evidence from experimental and epidemiology studies. Dr. Case discussed case reports of mesothelioma over the last several decades.

A case study of the translocation, bioprocessing and tissue interactions of EMP following inhalation exposure.

Human autopsied lung sections from a resident in the Quebec asbestos region were examined. The study utilized high resolution transmission electron microscopy, scanning transmission electron microscopy (HRTEM/STEM) with the analytical capabilities of electron energy loss spectroscopy (EELS) and energy dispersive spectroscopy (EDS) detectors. We report the first analytical ultrastructural characteristics of EMPs, detailing chemical concentration gradients inside the iron-protein coatings and lateral elemental gradients in the local tissue regions.

Overreliance on a single study: there is no real evidence that applying quality criteria to exposure in asbestos epidemiology affects the estimated risk.

A critical need exists for reliable risk management policies and practices that can effectively mitigate asbestos-related health threats, and such policies and practices need to be based on sound science that adequately distinguishes hazardous situations from those that are not. Toward that end, the disparate means by which study quality has been addressed in recent meta-analyses used to establish potency factors (K ( L ) and K ( M ) values) for asbestos cancer risks were compared by conducting additional sensitivity analyses. Results suggest that, other than placing undue emphasis on the influence of the K ( L ) and K ( M ) values reported from a single study, there appears to be little to no evidence of a systematic effect of study quality on K ( L ) or K ( M ) values; none of the findings warrant excluding studies from current or future meta-analyses.

Pleural mesothelioma surveillance: validity of cases from a tumour registry.

Background: Pleural mesothelioma is a rare tumour associated with exposure to asbestos fibres. Fewer than than one-quarter of cases registered in the Quebec Tumour Registry (QTR) have been compensated as work-related. While establishing a surveillance system, this led to questioning as to whether there has been over-registration of cases that are not authentic pleural mesotheliomas in the QTR.

Accuracy of urine cytology and the significance of an atypical category.

The "atypical urothelial cell" cytologic category is nonstandardized. We subclassify atypical cases to "atypical, favor a reactive process" or "atypical, unclear if reactive or neoplastic." We evaluated the predictive significance of atypical cases by looking at their histologic follow-up.

Risk of mesothelioma and occupational exposure to asbestos and man-made vitreous fibers: evidence from two case-control studies in Montreal, Canada.

Objective: To examine the effects of exposure to occupational asbestos and man-made vitreous fibers (MMVF) across a wide range of occupations on risk of mesothelioma.

Methodology: Two population-based case-control studies (1979-1986 and 1996-2001) provided 35 histologically confirmed mesothelioma cases and 1965 controls. A detailed job history was obtained to evaluate occupational exposure to many agents, including asbestos and MMVF.

Occupational exposure to asbestos and man-made vitreous fibers, and risk of lung cancer: evidence from two case-control studies in Montreal, Canada.

Objective: To examine the effects of occupational asbestos and man-made vitreous fibers (MMVF) on the risk of lung cancer in two population-based case-control studies entailing exposure at lower levels than in historic cohort studies.

Methodology: Study I (1979 to 1986) comprised 857 cases and 1066 population and cancer controls. Study II (1996 to 2001) comprised 858 cases and 1295 population controls.

Correlation of cytotechnologists' parameters with their performance in rapid prescreening of papanicolaou smears.

Background: Efficient quality control is essential to ensure high sensitivity of Papanicolaou (Pap) smears. For this purpose, rescreening of 10% random negative smears is increasingly felt to be ineffective. Rapid rescreening (RR) of all negative Pap smears is more practical and has received widespread acceptance, especially in Europe, although its sensitivity is difficult to monitor and its retrospective nature may influence the vigilance of the screeners.

Mineralogical and exposure determinants of pulmonary fibrosis among Québec chrysotile miners and millers.

Objectives: Lung fibre content was determined for 86 former chrysotile miners and millers in two Québec mining regions: Thetford mines (TM) and the Asbestos region (AR).

Methods: Fibres were assessed using transmission electron microscopy (TEM) and energy dispersive X-ray spectrometry (EDS). Asbestos body (AB) concentrations were assessed by microscopy of tissue digests.