Human health risk assessment of trace elements in commonly consumed herbs in Ibadan, Nigeria

Abstract

Elemental contamination of medicinal herbs is a major barrier to its general use. This study assessed the concentrations and health risks of Manganese, Iron, Copper, Zinc, Chromium, Cadmium, Cobalt, Nickel, Lead and Selenium via consumption of commonly sold medicinal herbs in Ibadan, Nigeria. Exactly 180 medicinal herb samples, purchased from 10 markets across Ibadan, were digested using aqua-regia. Quantification via Inductively Coupled Plasma-Optical Emission Spectrometry (ICP–OES) was done and validated via recovery (99.6–101%) and linearity (R2 > 0.999) procedures. The health risk associated with the consumption of medicinal herbs was estimated as Chronic Daily Intake (CDI), Hazard Quotient (HQ), Hazard Index (HI) and Target Carcinogenic Risk (TCR). The concentrations (mg kg-1) of Iron, Manganese, Copper, Zinc, Chromium, Selenium and Cobalt ranged from 65.4 to 369, 32.7–184, 17.0–96.0, 36.1–203, 5.41–30.5, 0.028–0.159 and 0.675–3.81 respectively. The average concentrations of Iron, Copper, Zinc and Chromium exceeded the WHO permissible limits. Although some elemental HQ values <1, all medicinal herbs had HI values > 1. Likewise, TCR values exceeded the 1 × 10–4 USEPA limit for cancer suggesting that consumption of these medicinal herbs is not safe for both adults and children.