Filtering by
- All Subjects: Environmental health
- Creators: Berger, Christopher
The objective of this dissertation was to investigate the occurrence and quantity of select, potentially harmful, anthropogenic chemicals in various environmental matrices and to explore the diagnostic value of analytical assays for informing public health decision-making. This dissertation (i) is the first to report spatio-temporal variations and estrogenic burdens of five parabens in sewage sludge from at the U.S. nationwide scale; (ii) represents the first China-wide survey to assess the occurrence and toxic emissions of parabens, triclosan, triclocarban, as well as triclocarban metabolites and transformation products contained in Chinese sewage sludge; (iii) documents the first use of a dispersive solid phase extraction method for indoor dust to measure dust-borne parabens, triclosan and triclocarban and estimating associated human exposures from dust ingestion; and (iv) is the first U.S. study to assess population-level alcohol and nicotine consumption in three U.S. communities using wastewater-based epidemiology (WBE). Obtained data on baseline levels of selected emerging contaminants in sewage sludge and indoor dust can serve to inform the future monitoring needs, risk assessment, and policy making. This work showcases the utility of WBE and urban metabolism metrology via dust and sewage sludge analysis to assess human behavior (e.g., drinking and smoking) and exposure risks more rapidly, efficiently and anonymously than traditional approaches can.
This study investigated the effect of environmental heat stress on physiological and performance measures during a ~4 mi time trial (TT) mountain hike in the Phoenix metropolitan area. Participants (n = 12; 7M/5F; age 21.6 ± 2.47 [SD]) climbed ‘A’ mountain (~1 mi) four times on a hot day (HOT; wet bulb globe temperature [WBGT] = 31.6°C) and again on a moderate day (MOD; WBGT = 19.0°C). Physiological and performance measures were made before and throughout the course of each hike. Mean pre-hike hydration status (urine specific gravity [USG]) indicated that participants began both HOT and MOD trials in a euhydrated state (1.016 ± 0.010 and 1.010 ± 0.008, respectively) and means did not differ significantly between trials (p = .085). Time trial performance was impaired by -11% (11.1 minutes) in the HOT trial (105 ± 21.7 min), compared to MOD (93.9 ± 13.1 min) (p = .013). Peak core temperatures were significantly higher in HOT (38.5 ± 0.36°C) versus MOD (38.0 ± 0.30°C) with progressively increasing differences between trials over time (p < .001). Peak ratings of perceived exertion were significantly higher in HOT (14.2 ± 2.38) compared to MOD (11.9 ± 2.02) (p = .007). Relative intensity (percent of age-predicted maximal heart rate [HR]), estimated absolute intensity (metabolic equivalents [METs]), and estimated energy expenditure (MET-h) were all increased in HOT, but not significantly so. The HOT condition reduced predicted maximal aerobic capacity (CRFp) by 6% (p = .026). Sweat rates differed significantly between HOT (1.38 ± 0.53 L/h) and MOD (0.84 ± 0.27 L/h) (p = .01). Percent body mass loss (PBML) did not differ significantly between HOT (1.06 ± 0.95%) and MOD (0.98 ± 0.84%) (p = .869). All repeated measures variables showed significant between-subjects effects (p < .05), indicating individual differences in response to test conditions. Heat stress was shown to negatively affect physiological and performance measures in recreational mountain hikers. However, considerable variation exists between individuals, and the degree of physiological and performance impairment is probably due, in part, to differences in aerobic fitness and acclimatization status rather than pre- or during-performance hydration status.