2514

Background The main impetus for the current assessment and management of hazardous chemicals is on its doses and health effect, but fewer studies have evaluated types of chemical mixtures, number of exposed chemicals and the vulnerable groups in general public. This study investigated exposure load through national biomonitoring program to pursue the exposure complexity over general population and to assess multipollutant exposure burden. Methods We obtained data from the Korean National Environmental Health Survey (2015-2017) and 6,167 participants were recruited including 571 preschoolers(3 to 5), 887 school-aged children(6 to 11) , 922 adolescent(12 to 18) and 3,787 adults(19 and older). All subjects were sampled for urinary levels of mercury, cadmium, polycyclic aromatic hydrocarbon(PAH) metabolites, volatile organic compound(VOC) metabolites, phthalate metabolites, parabens, environmental phenols, pyrethroid metabolite and cotinine. Additionally, blood lead and blood mercury levels were measured for ages 12 and older. In total, 26 chemicals were included in the analysis. We conducted several exposure load calculations with binary values for each individual analyte with different age groups and thresholds(limit of detection(LOD), 50^th, 75^th ,95^th). Results Using LOD as exposure thresholds, 20% of all participants(age 3 to 86) were exposed to more than 25 chemicals. With 50^th, 75^th ,95^th percentile thresholds, 20% of each population were exposed to more than 18, 11 and 2 chemicals, respectively. For participants who had the highest exposure to each chemical(95^th percentile) cadmium was the most frequent chemical and 17.2% of all population had more than one heavy metal(mercury, lead, cadmium) exposure. For each age group, the most frequent chemical differed; cadmium for adults, bisphenol F and A for adolescent, monobenzyl phthalate for school-aged children, and 1-hydroxyphenanthrene for preschoolers. Conclusions These results can improve multipollutant exposure burden assessment, especially for the highly susceptible population and can strengthen national chemical management practice.

2555

Background: Long-term exposure to particulate matter less than 2.5 μm (PM_2.5) is considered a risk factor for premature death. However, only a few studies have been conducted in areas with moderate PM_2.5 concentrations. Moreover, an aging society may be more susceptible to environmental exposure and future health impacts of PM_2.5. Methods: This study estimates hazard ratios (HRs) for all-cause and cause-specific mortality from long-term exposure to moderate PM_2.5 concentrations in the elderly populations of seven cities in South Korea. We also projected nationwide elderly mortality caused by long-term exposure to PM_2.5, accounting for population aging until 2045. Mortality in 1,720,230 elderly adults aged 65 years and older in 2008 was monitored across 2009-2016 and linked to modeled PM_2.5 concentrations. Results: A total of 421,100 deaths occurred in 2009-2016, and the mean of annual PM_2.5 concentration ranged between 21.1 μg/m³ and 31.9 μg/m³ in most regions. The overall HR for a 10 μg/m³ increase in a 36-month PM_2.5 moving average was 1.024 (95% confidence intervals: 1.009, 1.039). We estimated that 11,833 all-cause nationwide elderly deaths were attributable to PM_2.5 exposure. Annual death tolls may increase to 17,948 by 2045. However, if PM_2.5 is reduced to 5 μg/m³ by 2045, the tolls may decrease to 3,646. Conclusions: The long-term exposure to moderately high levels of PM_2.5 was associated with increased mortality risk among the elderly. Thus, PM_2.5 reduction in response to the projected aging-associated mortality in South Korea is critical.