Deterministic and probabilistic health risk assessment of heavy metals in liquid herbal cough formulations from Western Uganda

Abstract

This study investigated the concentrations and human health risks (carcinogenic and non-carcinogenic) associated with heavy metals in liquid herbal cough formulations obtained from the Western Region of Uganda. Twelve brands of registered (government authority) herbal cough formulations from reputable pharmacies were obtained and analysed. The mixtures were acid digested prior to Atomic Absorption Spectroscopy (AAS) analysis to quantify cadmium (Cd), copper (Cu), iron (Fe), lead (Pb), nickel (Ni), and zinc (Zn) in the herbal formulations, followed by human health risk assessment, using two different approaches: deterministic and probabilistic (Monte Carlo simulation). The results showed significant variations in heavy metal concentrations, with Cu, Fe, Ni, Cd, Pb, and Zn ranging from 0.020 to 1.272, not detected (ND) to 6.734, ND to 0.129, 0.002 to 0.051, ND to 0.190, and 0.043 to 0.527 mg/L, respectively, within the World Health Organization limit (WHO). Multivariate statistical analysis revealed that anthropogenic activities were the major source of heavy metal contamination. The hazard index (HI) values obtained ranged from 7.0 × 10^-4 to 2.59 × 10^-2 in children and 6.0 × 10^-4 to 2.49 × 10^-2 in adults, indicating extremely low non-carcinogenic risk (HI < 1) of exposure to heavy metals. Similarly, the incremental lifetime carcinogenic risks (ILCRs) of Ni, Pb, and Cd for both the children and adults were below the acceptable limit of 1.0 × 10^-4, indicating no carcinogenic health risk. Moreover, the probabilistic risk assessment revealed that Pb and Cd had less than a 0.01% chance of exceeding the WHO limit (negligible risk). Findings from this study indicate that heavy metal concentrations in the brands of herbal cough formulations from Western Uganda are below the safety thresholds and are safe for consumption under realistic exposure conditions.