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Background Fluoride may be a developmental neurotoxicant at elevated exposures. We merged new data from a prospective Odense Child Cohort (OCC) with results from two previous birth cohort studies from Mexico and Canada to characterize the dose–effect relationship in greater detail. Methods The OCC contributed 837 mother–child pairs to the total of >1500. We measured creatinine-adjusted urine-fluoride concentrations in maternal urine samples obtained during late pregnancy. Child IQ was determined at age 7 years using an abbreviated version of the Wechsler Intelligence Scales for Children. Findings from the three cohorts were used to calculate the joint benchmark concentration (BMC) and the lower confidence limit (BMCL) after adjustment for covariables. Results In the OCC, urine-fluoride concentrations varied between 0.08 and 3.04 mg/l (median 0.52 mg/l) but were not significantly associated with full-scale IQ at age 7 years (β = 0.08; 95% confidence interval −1.14 to 1.30 for a doubling in exposure). No difference was apparent between boys and girls. In the OCC, the BMC was 0.92 mg/l, with a BMCL of 0.30 mg/l. The joint analysis of all three cohorts showed a statistically significant association between urine-fluoride and IQ, with a BMC of 0.45 mg/l (BMCL, 0.28 mg/l), slightly higher than the BMC previously reported for the two North American cohorts alone. Conclusions As the BMCL reflects an approximate threshold for developmental neurotoxicity, the results suggest that pregnant women and children may need protection against fluoride toxicity. [ABSTRACT FROM AUTHOR]

Background Antibiotic prescription for uncomplicated upper respiratory tract infection (URTI) in children is not recommended but remains common. The primary objective was to evaluate the relationship between antibiotic prescription for URTI prior to age 2 and antibiotic prescription for URTI after age 2. It was hypothesized that antibiotic prescription for URTI in early childhood may increase the risk of antibiotic use for subsequent URTIs. The secondary objective was to investigate whether this relationship was different for acute otitis media (AOM), for which antibiotics may be indicated. Methods A prospective cohort study was conducted between December 2008 and March 2016 at 9 primary care practices in Toronto, Canada. Healthy children aged 0–5 years that met TARGet Kids! cohort eligibility criteria were included if they had at least one sick visit prior to age 2 and least one sick visit after age 2. Generalized Estimating Equation (GEE) models were used to evaluate this relationship while considering within-subject correlation. Results Of 2380 participants followed for a mean duration of 4.6 years, children who received an antibiotic prescription for URTI prior to age 2 had higher odds of receiving an antibiotic prescription for URTI in later childhood (adjusted odds ratio: 1.39; 95% confidence interval: 1.19 to 1.63; P  < .001). This relationship did not appear to be different for AOM compared to non-AOM URTI. Conclusion Antibiotic prescription for URTI before age 2 was associated with antibiotic prescription for URTI in later childhood. Reducing early life antibiotic prescription for URTI may be associated with reduction in antibiotic prescription for subsequent URTIs. [ABSTRACT FROM AUTHOR]

Background: Since 2006, banning smoking in cars with children has become a rapidly growing tobacco control policy. However, to date, there have been few studies examining support and correlates of support for car smoking bans, and none of the existing studies have been international in nature. We conducted such a study among smokers in four countries. Methods: 6716 adult current smokers from the 2007 Wave of the International Tobacco Control Four Country Survey, a nationally representative, longitudinal cohort telephone survey of smokers in the USA, Canada, UK and Australia. Controlling for demographics, heaviness of smoking, smoking health knowledge/beliefs and quit intentions, we compared support and correlates of support for banning smoking in cars with children across the four countries. Results: The majority of smokers supported banning smoking in cars with children. Support was highest in Australia (83%), followed by the UK (75%) and Canada (74%); support was lower—but still high—in the USA (60%). Support was highest among smokers who: had stronger quit intentions, were lighter smokers, had lower education, had no children in the home, believed that cigarette smoke is dangerous to non-smokers and could cause asthma in children, and were concerned about modelling smoking to children. Conclusions: These findings indicate that a majority of smokers in the four countries support banning smoking in cars with children, and lend support to banning smoking in cars with children. Additionally, they suggest that support may be increased by educating smokers about the dangers of cigarette smoke exposure. [ABSTRACT FROM AUTHOR]