Biomonitoring of DEET and DCBA in Canadian children following typical protective insect repellent use.

N,N-diethyl-m-toluamide (DEET) is an ingredient found in many consumer insect repellents and its use is recommended to Canadians by government agencies, including Health Canada, for protection against insect bites including mosquitos and ticks. The majority of research on DEET exposure and toxicokinetics in humans has focused on adult populations with little information from vulnerable populations, including children. We aimed to fill this knowledge gap by examining real-world exposure data for DEET and its metabolite 3-diethylcarbamoyl benzoic acid (DCBA) in a sample population of Canadian children. We conducted a 24-h observational exposure human biomonitoring study at three overnight summer camps in Ontario, Canada through July and August 2019. Participating children aged 7-13 years provided multiple spot urine samples over a 24-h period and completed a journal to document insect repellent use and factors that could influence absorption of DEET. Children were instructed to use insect repellent as they usually would while attending a summer camp. Exposure was quantified using the information from the participant's journal and the change in the mass of their insect repellent containers over the course of the study. A total of 389 urine samples were collected from 124 children. Among participants using insect repellent, urinary levels of DEET were elevated between 2 and 8 h post-application and decreased thereafter but remained qualitatively higher than concentrations in participants who did not use insect repellent on the study day, even at 18-22 h post-application. DCBA was the predominant metabolite of DEET exposure in urine. DCBA was elevated between 8 and 14 h post-application, and declined thereafter, but not to the level observed among those who did not use insect repellent on the study day. Children who used more insect repellent, or used higher concentration insect repellent (10%-30% DEET) excreted higher levels of DEET and DCBA. Excreted DEET and DCBA accounted for 0.001% (median) and 1.3% (median) of the estimated applied DEET, respectively. Children did not reach an undetectable level of DEET or DCBA in urine, even among those not using insect repellent during the study day, indicating a potentially complex multi-route exposure to insect repellents in a real world scenario. This work provides targeted biomonitoring data for children intentionally using DEET-based insect repellents for normal protective use, and will support the risk re-evaluation of DEET by Health Canada.

Development of an observational exposure human biomonitoring study to assess Canadian children's DEET exposure during protective use.

Biomonitoring data of N,N-diethyl-meta-toluamide (DEET) in children is scarce and limited to controlled exposure and surveillance studies. We conducted a 24-hour observational exposure and human biomonitoring study designed to estimate use of and exposure to DEET-based insect repellents by Canadian children in an overnight summer camp setting. Here, we present our study design and methodology. In 2019, children between the ages of 7 and 13 took part in the study (n = 126). Children controlled their use of DEET-based insect repellents, and provided an account of their activities at camp that could impact insect repellent absorption. Children provided a total of 389 urine samples throughout the study day, and reported the time that they applied insect repellent, which allowed us to contextualize urinary DEET and metabolite concentrations with respect to the timing of insect repellent application. DEET (2.3%

Activity-related dyspnea in older adults participating in the Canadian Longitudinal Study on Aging.

BACKGROUND: Dyspnea is associated with functional impairment and impaired quality of life. There is limited information on the potential risk factors for dyspnea in an older adult population. OBJECTIVES: Among older adults aged 45 to 85 years of age, what sociodemographic, environmental, and disease related factors are correlated with dyspnea? DESIGN: We used cross-sectional questionnaire data collected on 28,854 participants of the Canadian Longitudinal Study of Aging (CLSA). Multinomial regression was used to assess the independent effect of individual variables adjusting for the other variables of interest. KEY RESULTS: The adjusted odds ratios for dyspnea "walking on flat surfaces" were highest for obesity (OR, 5.71; 95%CI, 4.71-6.93), lung disease (OR, 3.91; 95%CI, 3.41-4.49), and depression (OR, 3.68; 95%CI, 3.15-4.29), and were greater than 2 for lower income, and heart disease. The effect of diabetes remained significant after adjusting for sociodemographics, heart disease and BMI (OR, 1.61; 95%CI, 1.39-1.86). Those with both respiratory disease and depression had a 12.78-fold (95%CI, 10.09-16.19) increased odds of exertional dyspnea, while the corresponding OR for the combination of heart disease and depression was 18.31 (95%CI, 13.4-25.01). CONCLUSIONS: In a community sample of older adults, many correlates of dyspnea exist which have significant independent and combined effects. These factors should be considered in the clinical context where dyspnea is out of proportion to the degree of heart and lung disease. Whether or not diabetes may possibly be a risk factor for dyspnea merits further investigation.

Urban air pollution and emergency department visits related to central nervous system diseases.

Ambient air pollution has been associated with adverse neurological health outcomes. Ambient pollutants are thought to trigger oxidative stress and inflammation to which vulnerable populations, such as elderly may be particularly susceptible. Our study investigated the possible association between concentrations of ambient air pollutants and the number of emergency department (ED) visits for nervous system disorders among people residing in a large Canadian city. A time-stratified case-crossover study design combining data from the National Ambulatory Care Reporting System (NACRS) and the National Air Pollution Surveillance (NAPS) between 2004 and 2015 was used. Two air quality health indices were considered in additional to specific pollutants, including carbon monoxide (CO), nitrogen dioxide (NO2), sulfur dioxide (SO2), ozone (O3) and fine particulate matter (PM2.5). Weather condition data were included in the models. ED visits with a discharge diagnosis were identified using ICD-10 codes (G00-G99). The analysis was stratified by sex and age, also by seasons. The associations were investigated in arrays organized as 18 strata and 15 time lags (in days) for each pollutant. Overall, 140,511 ED visits were included for the analysis. Most ED visits were related to episodic and paroxysmal diagnoses (G40-G47, 64%), with a majority of visits for migraines (G43, 39%). Among females, an increase of 0.1ppm ambient CO was associated with an increased risk of paroxysmal diagnoses at day 1 (RR = 1.019 (95%CI 1.004-1.033)), day 6 (1.024 (1.010-1.039)) and day 7 (1.022 (1.007-1.036). PM2.5 and SO2, and air quality indices were similarly associated with ED visits for episodic and paroxysmal disorders in days 6 and 7. Findings highlight that ambient air pollution is associated with an increased number of ED visits for nervous system disorders, particularly visits for paroxysmal diagnoses.

Temporal variation of total mercury levels in the hair of pregnant women from the Maternal-Infant Research on Environmental Chemicals (MIREC) study.

Prenatal exposure to total mercury (T-Hg) comes from both natural and anthropogenic sources. T-Hg can cross the blood-brain and placental barriers, and may be associated with future neurological and physiological dysfunctions. Scalp hair is an optimal and non-invasive indicator of chronic T-Hg exposure. As part of the Maternal-Infant Research on Environmental Chemicals (MIREC) Study, hair samples from 350 women were collected within weeks after giving birth, to determine temporal variations in T-Hg levels from preconception to delivery, and to compare these levels to corresponding levels measured in other matrices (maternal and umbilical cord blood, and infant's meconium). A maximum of 12 one-cm hair segments were cut starting at the scalp; segments closer to the scalp reflected recent exposure (within the last month). For proper comparison, the hair segments were matched with the collection dates for other matrices. GM hair T-Hg levels greatly decreased during pregnancy, from 0.26 µg g-1 (preconception or full-length hair) to 0.18 µg g-1 (at delivery or segments closer to the scalp). A similar decreasing trend was found for T-Hg in maternal blood: 1st trimester (0.60 µg L-1) to 3rd trimester (0.47 µg L-1). The median hair-to-blood ratios of T-Hg levels varied from 364 (1st trimester), to 408 (3rd trimester), to 229 (cord blood). Very low T-Hg levels were detected in meconium. Mercury levels in blood and hair correlated with consumption of large predatory fish.

The association between air pollution and hospitalization for patients with systemic lupus erythematosus in Chile: A daily time series analysis.

Genetic and environmental factors are thought to influence the activity of systemic lupus erythematosus (SLE), but relatively little is known about the effects of ambient air pollution. Using pollution data from air monitoring stations in the urban centers in Santiago Chile, along with daily patient hospitalization data from 2001 to 2012, an association between ambient air pollution and daily hospital admissions for SLE was tested using generalized linear models. Averaged over all regions pollutant mean 24 h concentrations were: 0.96 ppm carbon monoxide (CO), 64 ppb ozone (O3), 43 ppb nitrogen dioxide (NO2), 9 ppb sulphur dioxide (SO2), 29 µg/m3 particulate matter ≤ 2.5 µm in mean aerodynamic diameter (PM2.5), and 67 µg/m3 particulate matter ≤ 10 µm in diameter (PM10). The relative risk estimates in single pollutant models for an interquartile range (IQR) increase in pollutant were: RR = 1.34 (95% CI: 1.06-1.83) for SO2, RR = 1.60 (95% CI: 1.15-2.24) for CO, and RR = 1.41 (95% CI: 1.14-1.86) for PM2.5. In two-pollutant models, the significance of SO2 and PM2.5 persisted despite adjustments for each of the other measured pollutants. These findings suggest that acute increases in air pollution increase the risk of hospitalization with a primary diagnosis of SLE.