Durdana Khan

Background/Objectives: Urinary fluoride (UF) is the most well-established biomarker for fluoride exposure, and understanding its distribution can inform risk assessment for potential adverse systemic health effects. To our knowledge, this study is the first to report distributions of UF among youth according to sociodemographic factors in a nationally representative United States (US) sample. Methods: The study included 1191 children aged 6-11 years and 1217 adolescents aged 12-19 years from the National Health and Nutrition Examination Survey (NHANES) 2015–2016. We examined UF according to sociodemographic variables as well as Spearman correlations between UF and plasma fluoride. Survey-weighted quantile regression examined associations between tap water fluoride and UF levels adjusted for covariates. Results: The average age of participants was 12.5 years. The median (IQR) UF and water fluoride concentrations were 0.52 (0.50) mg/L and 0.39 (0.54) mg/L, respectively. Children had higher UF levels than adolescents and males had higher UF levels than females. UF differed according to race/ethnicity among both children and adolescents. Specifically, non-Hispanic Black youth tended to have higher UF levels than all participants except for those classified as other race/multiracial. UF and plasma fluoride were moderately correlated for children and adolescents. Higher water fluoride levels were associated with higher UF levels, and the magnitudes of association were larger at higher quantiles of UF (β = 0.14, p < 0.001; β = 0.20, p< 0.001 at the 25th and 50th quantiles, respectively). The magnitude of association between water fluoride and UF was the largest for non-Hispanic Black participants (predictive margin = 0.3, p < 0.001). Conclusions: Non-Hispanic Black youth in the US may have greater fluoride exposure and receive more of their fluoride intake from tap water than youth of other races/ethnicities. Factors contributing to potential racial/ethnic disparities in fluoride exposure within the US warrant further investigation so that they can be mitigated to reduce the potential for harm.

Current conceptualizations of dental caries etiology center primarily on the local role of sugar, starch, or other fermentable carbohydrates on tooth enamel demineralization—a well-established and empirically supported mechanism. However, in addition to this mechanism, studies dating back to the early 1900s point to an important systemic role of diet and nutrition, particularly from pasture-raised animal-source foods (ASF), in dental caries etiology and arrest. Findings from animal and human studies suggest that adherence to a diet high in calcium, phosphorus, fat-soluble vitamins A and D, and antioxidant vitamin C, as well as low in phytates, may contribute to arrest and reversal of dental caries, particularly among children. Furthermore, findings from observational and experimental studies of humans across the life-course suggest that fat-soluble vitamins A, D, and K2 may interact to protect against dental caries progression, even within a diet that regularly contains sugar. While these historic studies have not been revisited in decades, we emphasize the need for them to be reinvestigated and contextualized in the 21st century. Specifically, methodologically rigorous studies are needed to reinvestigate whether historical knowledge of systemic impacts of nutrition on dental health can help to inform current conceptualizations of dental caries etiology, prevention, and arrest.

Background: Shift work, especially rotating and night shift work, has been linked to a wide range of detrimental health outcomes. Occupational factors like shift work and their potential impact on cognitive functions have received little attention, and the evidence is inconclusive. The objective of our study is to explore associations between shift work exposure and cognitive impairment indicators based on comparisons with the normative standards from the Canadian population. Methods: Cross-sectional analyses were performed using baseline Canadian Longitudinal Study on Aging database, including 47,811 middle-aged and older adults (45–85 years). Three derived shift work variables were utilized: ever exposed to shift work, shift work exposure in longest job, and shift work exposure in current job. Four cognitive function tests were utilized, Rey Auditory Verbal Learning Tests (immediate and delayed) representing memory domain, and Animal Fluency, and Mental Alteration, representing the executive function domain. All cognitive test scores included in study were normalized and adjusted for the participant’s age, sex, education and language of test administration (English and French), which were then compared to normative data to create “cognitive impairment’ variables. Unadjusted and adjusted multivariable logistic regression models were used to determine associations between shift work variables and cognitive impairment individually (memory and executive function domains), and also for overall cognitive impairment. Result: Overall, one in every five individuals (21%) reported having been exposed to some kind of shift work during their jobs. Exposure to night shift work (both current and longest job) was associated with overall cognitive impairment. In terms of domain-based measures, night shift work (longest job) was associated with memory function impairment, and those exposed to rotating shift work (both current and longest job) showed impairment on executive function measures, when compared to daytime workers. Conclusion: This study suggests disruption to the circadian rhythm, due to shift work has negative impact on cognitive function in middle-aged and older adults and this warrants further investigation.

Objective: To investigate the association between shift work exposure and frailty. Methods: Longitudinal secondary data analyses were performed using Canadian Longitudinal Study on Aging. Individuals aged 45 to 85 years were included at baseline (N = 47,740). Primary shift work (SW) variables were derived at baseline: ever exposed to SW, SW exposure in longest job, and SW exposure in current job. Multinomial regression models were constructed to evaluate the association between SW and frailty at 3 years of follow-up. Results: Participants ever exposed to SW were associated with frailty compared with those who worked only daytime. Particularly, females worked in rotating shifts in their longest jobs were more likely to be classified as frail compared with those who worked only daytime. Conclusions: This study suggests that SW may play a role in development of frailty and this warrants further investigation.

Objective: A wide range of negative health outcomes have been associated with shift work (SW) particularly night and rotating SW. However, little is known about effects of SW exposure on reproductive health outcomes. The objective of our study is to prospectively investigate the association between SW exposure and the variations in age at natural menopause among adult Canadian workers. Methods: Secondary data analyses were performed using the Canadian Longitudinal Study on Aging database. Premenopausal women (N = 3,688) at baseline were followed prospectively for 3 years. Three derived variables were used to measure SW primary exposure: 1) ever exposed to SW, 2) SW exposure in current job, and 3) SW exposure in the longest job. Cox proportional hazard regression models were used to evaluate risk of variations in age at natural menopause after adjusting for potential confounders. Result: One out of five women (20%) reported to be ever exposed to SW during their jobs. Overall, women who were ever exposed to SW were significantly associated with a delayed onset of menopause compared with daytime workers (hazard ratios [HR] = 0.77, 95% CI, 0.61-0.98). Particularly, when compared with daytime workers, rotating shift worker in the current and longest job were significantly related to delayed onset of menopause (HR = 0.64, 95% CI, 0.46-0.89 and HR = 0.65, 95% CI, 0.49-0.86), respectively. Conclusion: Our results suggest a relationship between rotating shift and delayed onset of menopause. We speculate that disruptive circadian stimuli may play a role in menopausal onset and this warrants further investigation. Video Summary: http://links.lww.com/MENO/A940.