Maryam Shekarrizfard

Spatial variations in ambient ultrafine particle concentrations and the risk of incident prostate cancer: A case-control study

Background: Diesel exhaust contains large numbers of ultrafine particles (UFPs, <0.1 &mgr;m) and is a recognized human carcinogen. However, epidemiological studies have yet to evaluate the relationship between UFPs and cancer incidence. Methods: We conducted a case‐control study of UFPs and incident prostate cancer in Montreal, Canada. Cases were identified from all main Francophone hospitals in the Montreal area between 2005 and 2009. Population controls were identified from provincial electoral lists of French Montreal residents and frequency‐matched to cases using 5‐year age groups. UFP exposures were estimated using a land use regression model. Exposures were assigned to residential locations at the time of diagnosis/recruitment as well as approximately 10‐years earlier to consider potential latency between exposure and disease onset. Odds ratios (OR) and 95% confidence intervals (95% CI) were calculated per interquartile range (IQR) increase in UFPs (approximately 4000 particles/cm3) using logistic regression models adjusting for individual‐level and ecological covariates. Results: Ambient UFP concentrations were associated with an increased risk of prostate cancer (OR=1.10, 95% CI: 1.01, 1.19) in fully adjusted models when exposures were assigned to residences 10‐years prior to diagnosis. This risk estimate increased slightly (OR=1.17, 95% CI; 1.01, 1.35) when modeled as a non‐linear natural spline function. A smaller increased risk (OR=1.04, 95% CI: 0.97, 1.11) was observed when exposures were assigned to residences at the time of diagnosis. Conclusions: Exposure to ambient UFPs may increase the risk of prostate cancer. Future studies are needed to replicate this finding as this is the first study to evaluate this relationship. HighlightsWe conducted a case‐control study of UFPs and prostate cancer.Exposures were estimated using a land use regression model.Ambient UFPs were associated with an increased risk of prostate cancer.Risks were greatest when using addresses 10‐years prior to diagnosis.

The association between the incidence of postmenopausal breast cancer and concentrations at street-level of nitrogen dioxide and ultrafine particles

Background There is scant information as to whether traffic‐related air pollution is associated with the incidence of breast cancer. Nitrogen dioxide (NO2) and ultrafine particles (UFPs, <0.1 &mgr;m), are two pollutants that capture intra‐urban variations in traffic‐related air pollution and may also be associated with incidence. Methods We conducted a population‐based, case‐control study of street‐level concentrations of NO2 and UFPs and incident postmenopausal breast cancer in Montreal, Canada. Incident cases were identified between 2008 and 2011 from all but one hospital that treated breast cancer in the Montreal area. Population controls were identified from provincial electoral lists of Montreal residents and frequency‐matched to cases using 5‐year age groups. Concentrations of NO2 and UFPs were estimated using two separate land‐use regression models. Exposures were assigned to residential locations at the time of recruitment, and we identified residential histories of women who had lived in these residences for 10 years or more. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using logistic regression models adjusting for individual‐level and ecological covariates. We assessed the functional form of NO2 and UFP exposures using natural cubic splines. Results We found that the functional form of the response functions between incident postmenopausal breast cancer and concentrations of NO2 and UFPs were consistent with linearity. For NO2, we found increasing risks of breast cancer for all subjects combined and stronger associations when analyses were restricted to those women who had lived at their current address for 10 years or more. Specifically, the OR, adjusted for personal covariates, per increase in the interquartile range (IQR=3.75 ppb) of NO2 was 1.08 (95%CI: 0.92–1.27). For women living in their homes for 10 years or more, the adjusted OR was 1.17 (95%CI: 0.93–1.46; IQR=3.84 ppb); for those not living at that home 10 years before the study, it was 0.93 (95%CI: 0.64, 1.36; IQR=3.65 ppb). For UFPs, the ORs were lower than for NO2, with little evidence of association in any of the models or sub‐analyses and little variability in the ORs (about 1.02 for an IQR of ˜3500 cm−3). On the other hand, we found higher ORs amongst cases with positive oestrogen and progesterone receptor status; namely for NO2, the OR was 1.13 (95%CI: 0.94–1.35) and for UFPs it was 1.05 (95%CI: 0.96–1.14). Conclusions Our findings suggest that exposure to ambient NO2 and UFPs may increase the risk of incident postmenopausal breast cancer especially amongst cases with positive oestrogen and progesterone receptor status. HighlightsThis is a population‐based case‐control study of postmenopausal breast cancer.We developed land‐use regression models for NO2 and ultrafine particles.We linked the exposure surfaces to subjects’ addresses.We found associations for NO2.Little evidence for associations with ultrafines.

Estimating the health benefits of planned public transit investments in Montreal

Background Since public transit infrastructure affects road traffic volumes and influences transportation mode choice, which in turn impacts health, it is important to estimate the alteration of the health burden linked with transit policies. Objective We quantified the variation in health benefits and burden between a business as usual (BAU) and a public transit (PT) scenarios in 2031 (with 8 and 19 new subway and train stations) for the greater Montreal region. Method Using mode choice and traffic assignment models, we predicted the transportation mode choice and traffic assignment on the road network. Subsequently, we estimated the distance travelled in each municipality by mode, the minutes spent in active transportation, as well as traffic emissions. Thereafter we estimated the health burden attributed to air pollution and road traumas and the gains associated with active transportation for both the BAU and PT scenarios. Results We predicted a slight decrease of overall trips and kilometers travelled by car as well as an increase of active transportation for the PT in 2031 vs the BAU. Our analysis shows that new infrastructure will reduce the overall burden of transportation by 2.5 DALYs per 100,000 persons. This decrease is caused by the reduction of road traumas occurring in the inner suburbs and central Montreal region as well as gains in active transportation in the inner suburbs. Conclusion Based on the results of our study, transportation planned public transit projects for Montreal are unlikely to reduce drastically the burden of disease attributable to road vehicles and infrastructures in the Montreal region. The impact of the planned transportation infrastructures seems to be very low and localized mainly in the areas where new public transit stations are planned. HighlightsAn integrated burden of transportation in association with planned modifications of the public transit infrastructure.Based on our results planned public transit projects in Montreal will not reduce significantly the burden of transportation.Future work needs to address land use and public transit projects needed to further reduce the burden of transportation.