The Canadian Healthy Infant Longitudinal Development (CHILD) birth cohort study: Assessment of environmental exposures

The Canadian Healthy Infant Longitudinal Development birth cohort was designed to elucidate interactions between environment and genetics underlying development of asthma and allergy. Over 3600 pregnant mothers were recruited from the general population in four provinces with diverse environments. The child is followed to age 5 years, with prospective characterization of diverse exposures during this critical period. Key exposure domains include indoor and outdoor air pollutants, inhalation, ingestion and dermal uptake of chemicals, mold, dampness, biological allergens, pets and pests, housing structure, and living behavior, together with infections, nutrition, psychosocial environment, and medications. Assessments of early life exposures are focused on those linked to inflammatory responses driven by the acquired and innate immune systems. Mothers complete extensive environmental questionnaires including time-activity behavior at recruitment and when the child is 3, 6, 12, 24, 30, 36, 48, and 60 months old. House dust collected during a thorough home assessment at 3–4 months, and biological specimens obtained for multiple exposure-related measurements, are archived for analyses. Geo-locations of homes and daycares and land-use regression for estimating traffic-related air pollution complement time-activity-behavior data to provide comprehensive individual exposure profiles. Several analytical frameworks are proposed to address the many interacting exposure variables and potential issues of co-linearity in this complex data set

The Canadian Urban Environmental Health Research Consortium - A protocol for building a national environmental exposure data platform for integrated analyses of urban form and health

Background: Multiple external environmental exposures related to residential location and urban form including, air pollutants, noise, greenness, and walkability have been linked to health impacts or benefits. The Canadian Urban Environmental Health Research Consortium (CANUE) was established to facilitate the linkage of extensive geospatial exposure data to existing Canadian cohorts and administrative health data holdings. We hypothesize that this linkage will enable investigators to test a variety of their own hypotheses related to the interdependent associations of built environment features with diverse health outcomes encompassed by the cohorts and administrative data. Methods: We developed a protocol for compiling measures of built environment features that quantify exposure; vary spatially on the urban and suburban scale; and can be modified through changes in policy or individual behaviour to benefit health. These measures fall into six domains: air quality, noise, greenness, weather/climate, and transportation and neighbourhood factors; and will be indexed to six-digit postal codes to facilitate merging with health databases. Initial efforts focus on existing data and include estimates of air pollutants, greenness, temperature extremes, and neighbourhood walkability and socioeconomic characteristics. Key gaps will be addressed for noise exposure, with a new national model being developed, and for transportation-related exposures, with detailed estimates of truck volumes and diesel emissions now underway in selected cities. Improvements to existing exposure estimates are planned, primarily by increasing temporal and/or spatial resolution given new satellite-based sensors and more detailed national air quality modelling. Novel metrics are also planned for walkability and food environments, green space access and function and life-long climate-related exposures based on local climate zones. Critical challenges exist, for example, the quantity and quality of input data to many of the models and metrics has changed over time, making it difficult to develop and validate historical exposures. Discussion: CANUE represents a unique effort to coordinate and leverage substantial research investments and will enable a more focused effort on filling gaps in exposure information, improving the range of exposures quantified, their precision and mechanistic relevance to health. Epidemiological studies may be better able to explore the common theme of urban form and health in an integrated manner, ultimately contributing new knowledge informing policies that enhance healthy urban living

Temporal trends of phthalate exposures during 2007–2010 in Swedish pregnant women

Background: The general population is exposed to phthalates, a group of chemicals with strong evidence for endocrine disrupting properties, commonly used in a large number of consumer products. Based on published research and evidence compiled by environmental agencies, certain phthalate applications and products have become restricted, leading to an increasing number of “new generation compounds” coming onto the market during recent years replacing older phthalates. Some examples of such newer compounds are di-iso-nonyl phthalate (DiNP), di-iso-decyl phthalate (DiDP), and most recently di-isononyl-cyclohexane-1,2-dicarboxylate (DiNCH). Objectives: In order to evaluate temporal trends in phthalate exposure, first trimester urinary biomarkers of phthalates were measured in the Swedish SELMA study over a period of 2.5 years (2007–2010). Methods: We collected first morning void urine samples around week 10 of pregnancy from 1651 pregnant women. Spot samples were analyzed for 13 phthalate metabolites and one phthalate replacement and least square geometric mean (LSGM) levels of the metabolites were compared between the sampling years when adjusted for potential confounders. Results: All 14 metabolites were detectable in more than 99% of the SELMA subjects. The levels were generally comparable to other studies, but the SELMA subjects showed slightly higher exposure to butyl-benzyl phthalate (BBzP) and di-butyl phthalate (DBP). Di-ethyl-hexyl phthalate (DEHP) metabolites levels decreased while DiNP, DiDP/di-2-propylheptyl phthalate (DPHP), and DiNCH metabolites levels increased during the sampling period. Conclusions: Urinary metabolite levels of the older phthalates and more recently introduced phthalate replacement compound changed during the short sampling period in this Swedish pregnancy cohort. Our results indicate that replacement of phthalates can make an impact on human exposure to these chemicals. During this particularly vulnerable stage of life, phthalate exposures are of particular concern as the impacts, though not immediately noticeable, may increase the risk for health effects later in life