Modifying factors and temporal trends of adverse health effects of short-term exposure to PM2.5 in Canada (2001-2018).

Considerable evidence has been accumulated on serious acute health outcomes associated with short-term exposure to ambient fine particulate matter (PM2.5). Modifying factors of those associations, however, have been less explored and need further analyses. In this national study, we investigated whether short-term effects of PM2.5 are modified according to region, cause of mortality/hospitalization, season, age, and sex. PM2.5-related adverse health effects were estimated by an ecological time-series study, covering about 80 % of the Canadian population for 18 years (2001-2018). We estimated city-specific associations using daily averages of PM2.5 and temperature, and daily counts of hospitalizations and mortality (non-accidental all-cause, circulatory, and respiratory). National and regional associations were then estimated with a 2-stage model. We considered potential modifying factors of PM2.5-related adverse health effects, and examined linear trends in the annual associations. Nationally, PM2.5 exposure was associated with both hospitalizations and mortality, and there was evidence of differences by the modifying factors. Of the various causes, circulatory mortality and respiratory hospitalization were more attributable to PM2.5 exposure. We found regional differences for both all-cause hospitalization and all-cause mortality, and seasonal differences for respiratory hospitalization (warm season) and circulatory hospitalization (cold season). Circulatory mortality risk was significant for seniors and females. All-cause hospitalizations appeared to gradually decrease over time, but annual all-cause mortality remained constant at 0.6 % of the population. Adverse health effects of PM2.5 exposures may depend on not only PM2.5 concentration, but also other factors (region, cause, season, age, sex). National estimates for the baseline (age ≥ 1 year, both sexes) risk cannot be interpreted without consideration of the differences by modifying factors. Study findings can be used by seniors, women, and those who have pre-existing health conditions to make informed decisions regarding their health risks from daily exposure to ambient PM2.5.

Measurement of 24 phthalate metabolites in 1st trimester urine samples: The MIREC study.

Phthalates are non-persistent chemicals measured as metabolites in urine. Over time, new metabolites have been identified. In the original Maternal-Infant Research on Environmental Chemicals (MIREC) study (2008-2011), we measured 11 phthalate metabolites in first trimester urine samples. The goal of the present study was to develop a method to measure new metabolites, to increase the sensitivity for some previously measured metabolites, and to measure these new metabolites in biobanked urine samples from MIREC participants. Using Ultra Performance Liquid Chromatography with a tandem mass spectrometer, we developed a method to measure 24 metabolites from 10 different parent phthalates. Chromatographic interpretation of some of the di-iso-decyl phthalate metabolites (mono-(2-propyl-6oxoheptyl) phthalate (MOiDP), mono-(2,7-methyl-7-carboxyheptyl) phthalate (MCiNP), mono-(2-propyl-6-hydroxy-heptyl) phthalate (MHiDP)) and di-iso-nonyl phthalate metabolites (mono(oxo-isononyl) phthalate (MOiNP), mono(carboxy-isooctyl) phthalate (MCiOP), mono(hydroxy-isononyl) phthalate (MHiNP) and mono-isononyl phthalate (MiNP)) was challenging as these are complex isomeric mixtures. To validate and confirm our quantitation peaks, an assay using a high-resolution detection technique was developed on a Quadrupole Time-of-Flight (QToF) system. This system has a mass resolution of at least 0.005 amu, compared to 0.5 amu for the MS/MS detector. Using the QToF system, the distinction between an isomer and possible interference was achieved with the use of the exact mass. In about 1800 MIREC samples, mono-cyclo-hexyl phthalate (MCHP), mono-(7-carboxy-n-heptyl) phthalate (MCHpP), mono-iso-decyl phthalate (MiDP), and mono-n-octyl phthalate (MnOP) were rarely detected, while detection of MMP was improved. MCiOP, MiNP and MCiNP had to be reported semi-quantitatively. Given the complexity of isomeric mixtures of some phthalates, researchers must be careful in their determination of the analytes and the approach used in their quantification when generating biomonitoring data. This study produced biomonitoring data for a large population of pregnant people that can be used in risk assessment of phthalates. Future work will examine associations with birth and child outcomes.