Claude Ostiguy

Estimating occupational exposure to carcinogens in Quebec

BACKGROUND We estimated the extent of exposure to occupational carcinogens in Quebec, Canada, to help raise awareness of occupational cancers. METHODS Proportions of workers exposed to 21 recognized and 17 probable carcinogens (according to Quebec occupational health regulation and the International Agency for Research on Cancer [IARC] classification) were extracted from various sources: workplace monitoring data, research projects, a population survey, radiation protection data, exposure estimates from the Carcinogen Exposure Canada (CAREX Canada) Project database, and published exposure data. These proportions were applied to Quebec labor force data. RESULTS Among the 38 studied, carcinogens with the largest proportions of exposed workers were solar radiation (6.6% of workers), night shift work/rotating shift work including nights (6.0%), diesel exhaust fumes (4.4%), wood dust (2.9%) and polycyclic aromatic hydrocarbons (2.0%). More than 15 carcinogens were identified in several industrial sectors, and up to 100,000 young workers are employed in these sectors. CONCLUSION Although crude, estimates obtained with different data sources allow identification of research and intervention priorities for cancer in Quebec.

Contribution of Breathing Frequency and Inhalation Flow Rate on Performance of N95 Filtering Facepiece Respirators

The investigation of particle penetration through filtering facepiece respirators under cyclic flows is very necessary because cyclic flows represent actual breathing flow patterns. This article reports the development of a procedure to investigate the individual impact of breathing frequency and flow rate on the performance of N95 filtering facepiece respirators. Experiments were performed for two peak inhalation flows (PIFs; 135 and 360 l min(-1)) and two breathing frequencies [24 and 42 breaths per minute (BPM)] for a total of four cyclic flows (Flow A: 135 l min(-1) and 24 BPM; Flow B: 135 l min(-1) and 42 BPM; Flow C: 360 l min(-1) and 24 BPM; and Flow D: 360 l min(-1) and 42 BPM). Each experiment was performed using two different set-ups: the first set-up included both inhalations and exhalations through the filter media and test chamber, while with the second set-up, only inhalation flows were considered. The results showed that, for the most penetrating particle size range, an increase in both PIF and breathing frequency could potentially enhance the penetration with both set-ups; however, the effect of PIF was observed to be much more pronounced than that of frequency. The results indicated that with both set-ups, when the PIF was increased from 135 to 360 l min(-1) (for the given frequency: 24 or 42 BPM), an increase of up to 139-152% in penetration was observed. On the other hand, only a 10-16% increase in penetration occurred when the frequency was changed from 24 to 42 BPM (for a given PIF: 135 or 360 l min(-1)). This suggests that, from low to high respiratory efforts, a huge portion of penetration enhancement is due to PIF variations and only a small portion is contributed by frequency variations.

Evaluation of N95 Filtering Facepiece Respirator Efficiency with Cyclic and Constant Flows

An increasing demand for protecting workers against harmful inhalable ultrafine particles (UFPs), by means of filtering facepiece respirators (FFRs), necessitates assessing the efficiency of FFRs. This article evaluates the penetration of particles, mostly in the ultrafine range, through one model of N95 FFRs exposed to cyclic and constant flows, simulating breathing for moderate to heavy work loads. The generated particles were poly-dispersed NaCl, within the range of 10–205.4 nm. The tests were performed for several cyclic flows, with mean inhalation flows (MIFs) ranging from 42 to 360 L/min, and constant flows with the same range. The measurements were based on filter penetration and did not consider particle leakage. With the penetrations recorded for the selected constant and cyclic flows, the worst-case scenario penetrations at the most penetrating particle size (MPPS) were obtained. The MPPS penetrations measured with the cyclic and constant flows equivalent to minute volume, MIF and peak inhalation flow (PIF) of the cyclic flows were then compared. It was indicated that the constant flows equivalent to the minute volume or PIF of the cyclic flow could not accurately represent the penetration of the corresponding cyclic flow: the constant flow equal to the minute volume of the cyclic flow significantly underestimated the MPPS penetration of the corresponding cyclic flow, while the constant flow equal to the PIF of the cyclic flow overestimated it. On the other hand, for the constant flow equal to the MIF of the cyclic flow, the MPPS penetrations were almost equal for both the constant and cyclic flows, for the lower flow rates (42 to 170 L/min). For higher flow rates (230 to 360 L/min), however, the MPPS penetration was exceeded under the constant flows, compared with the corresponding cyclic flows. It was therefore concluded that the constant flow equal to the MIF of the cyclic flow could better predict the results of corresponding cyclic flow, since it could provide the MPPS penetrations (worst-case scenario) equal to or greater than the MPPS penetrations of the cyclic flow.

Evaluation of the SureSpot Direct-Reading Instrument for the Determination of Polymeric MDI Aerosols

Recent studies in our laboratories have focused on the reliability of direct-reading instruments for the determination of airborne isocyanate concentrations. The evaluation of airborne isocyanates is complicated because these substances exist as diisocyanate monomers and polyisocyanate oligomers, both in the vapor and aerosol phases. The studies showed that a number of direct-reading instruments, including the SureSpot test kit, do not allow an accurate determination of isocyanates in the aerosol phase. Using a test chamber, concentrations of various commercial polymeric methylenediphenyl diisocyanates (PMDI) were generated in the aerosol phase to examine the correlation between the SureSpot monitor and two laboratory methods. The results obtained with the SureSpot and laboratory methods correlated poorly. More precisely, the results indicated that the SureSpot direct-reading instrument had a distinctive response to each commercial PMDI and, in addition, it was not accurate for the determination of total PMDI in the aerosol phase. It seemed that the analytical response of the SureSpot is based on a calibration curve only reliable for MDI and not for the determination of PMDIs in the aerosol phase. Further investigation also indicated that the calibration provided by the manufacturer could not be converted into a linear curve over the suggested MDI concentrations range. An appropriate calibration procedure was developed in our laboratories for the SureSpot to accurately determine all commercial PMDIs without great variability.

Risk Management and Good Practices Guidelines

Abstract Numerous studies indicate that workers exposed to some engineered nanomaterials (ENMs) could be at risk of developing adverse health effects. In the absence of regulated occupational exposure limits and because toxicological data as well as exposure levels are still limited, the risk is normally impossible to fully quantify in most workplaces. Alternative qualitative or semiquantitative approaches such as control banding are widely used to take into consideration these uncertainties to safely manage the exposures in several situations. Overall, risk management programs based on the precautionary approach should be carried out to minimize exposures to ENMs. These programs, elaborated at the design stage, should include intrinsic safety, engineering controls, administrative procedures, and personal protective equipment. Train and raise the safety awareness of workers, evaluate the efficiency of the preventive measures, and establish safe work practices and good emergency plans are essential constituents of the prevention program.

Mapping the Use of Engineered NM in Quebec's Industries and Research Laboratories

Engineered NanoMaterials (NM) offer an opportunity to develop a wide variety of new products with unique properties but many studies have shown potential OHS risks specific to NM. Addressing these risks requires knowledge about release of NM into the workplaces. This research aimed to map the state of nanotechnology OHS practices in Quebec through a questionnaire following a first contact by telephone when possible and by compiling the type and volumes of NM used as well as gathering information related to the working conditions and OHS aspects. This survey was conducted among 1310 Quebec industries and 653 researchers working in different specialties potentially involved in the development/production/distribution/integration of NM and use of NM containing products. Overall, 90 questionnaires, including 51 from the industries, were completed. These showed that NM are mainly used into the powder form, in many different sectors and deserve a wide range of markets. The prevention measures implemented vary widely from a workplace to another but about one third of the participants report that they have implemented NP adapted prevention measures but they remain worried on some specific operations. More than 50% of the participants request more information about the safe laboratory/plant design, toxicity, regulation, good work practices and prevention measures, efficiency of personal protective equipment and environmental impacts.

Carcinogens exposure prevalence as a first step toward preventing occupational cancers: challenges and drawbacks

Objectives Ascertainment of the occurrence of exposure to carcinogens and its quantification are the first steps toward preventing occupational cancer. A descriptive study was set up to estimate the importance of potential exposure to carcinogens among the Quebec 3,5 million workers. Methods For agents considered carcinogenic or probably carcinogenic to humans in the Quebec legislation and in the IARC classification (groups 1 and 2A), we obtained estimates of potential exposures by industrial sector from 5 sources: laboratory analyses of chemicals monitored in Quebec workplaces by public health agencies, the 1998 Quebec Social and Health Population Survey, a few specific industrial hygiene research projects, data produced by CAREX Canada (the University of British Columbia equivalent of CAREX), and published data from the French SUMER survey and from the MATGÉNÉ job-exposure matrices project. Labour force data were extracted from the 2006 Canadian Census. Results Potential exposure data were obtained for 19 recognised and 19 suspected carcinogens. Using CAREX Canada data (available for the largest number of carcinogens), the most common exposures were solar radiation (5.7%), diesel exhaust fumes (4.4% of workers), polycyclic aromatic hydrocarbons (2.0%) and wood dust (1.8%). Occasionally, different estimates were obtained from other sources of data; for example, the 1998 Quebec population survey produced a larger estimate for wood dust exposure (10.7%). Conclusions Variations between estimates obtained with different data sources pose a challenge for calculation of the exposed population. However, targeting key population groups for intervention and identification of research priorities and knowledge gaps remain feasible with these data.