LEAD AND ARSENIC INADVERTENT OCCUPATIONAL HEALTH RISK ASSESSMENT IN INSTRUCTIONAL LABORATORIES IN MOI UNIVERSITY AND UNIVERSITY OF ELDORET, KENYA

Abstract

Settled surface indoor dust is of environmental importance since it can act as a medium of human exposure to heavy metals. Universities laboratories are involved in varied activities some of which may expose arsenic (As) and lead (Pb) to workers. The objective of this study was to estimate potential health risks due to inadvertent occupational exposure to As and Pb in select instructional laboratories within Uasin Gishu County, Kenya. The research employed a cross-sectional study design. Sampled indoor settled dusts in ten sampling stations from Moi University and University of Eldoret were analyzed for Pb and As concentrations using F-AAS and XRF, respectively, alongside a descriptive study on laboratory safety and hygiene. Univariate data analysis, one-way ANOVA and t-test were done to describe and ascertain variations and the results compared with internationally stipulated standards. Estimation of occupational health risk was done in accordance with risk assessment models as described by U.S. EPA. The study found out that there were no vacuum cleaning equipment, waste collection schedules and occupational injuries and illness form. The facilities lacked a risk assessment tool, electronic inventories of safety data sheets (SDS) and personal protective equipment (PPE) were not only inadequate but also poorly maintained. Mean Pb levels ranged from 344.890±12.267-754.438±76 mg/kg, which were significantly above WHO/FAO: EU: U.S. EPA (95% CI: p = 0.000: p = 0.000-0.01197: p = 0.000-0.0991) recommended standards, respectively. Mean As levels ranged from 0.42-131.73 mg/kg, which were significantly lower (p = 0.01210.998) in most (80%) sampling stations than EU/FAO/WHO standards while 60% of the stations significantly (p = 0.024-0.795) surpassed U.S. EPA standards. NonCarcinogenic risk for Pb HQ results in the entire study area were found to be above unit (p = 0.048607; p = 0.00413). These results were in agreement with both central tendency exposure (CTE) and reasonable maximum exposure (RME) non-carcinogenic risks. However, As HQ results in the entire study area were found to be less than unit (p = 0.243459; p = 0.20453) for men and women, respectively. Aggregate HI were significantly above unit (p = 0.053234 and p = 0.004819). Comparison with U.S. EPA’s acceptable excess lifetime cancer risk (ELCR) of 1x10-6 - 1x10-4 in the entire area found out that men Pb risk was within acceptable levels (p = 0.382236) while women risk was significantly higher (p = 0.035785). The CTE and RME carcinogenic risks for Pb were both within ELCR levels. Arsenic cancer risk was within acceptable ELCR levels (p = 0.180078; p = 0.155792), however, CTE and RME cancer risks were above ELCR acceptable levels for men and women, respectively. Aggregate risks were all above acceptable risks. The study concluded that RMD work-unit was found to be the most exposed work-unit for both Pb and As cancer and non-cancer risks and that instructional laboratories are not entirely safe from Pb and As exposure risks. The study recommends that universities adhere to laboratory safety rules, come up with chemical hygiene plans (CHP) and process-specific risk assessments.