Heavy Metals and Pesticide Residues in Medicinal Plants of Uzbekistan: Determination and Health Risk Assessment

Abstract

Medicinal plants are a cornerstone of Uzbekistan's traditional healthcare system and pharmaceutical industry, yet industrial development and agricultural chemical use increasingly threaten their safety. This study determined six heavy metals (Pb, Cd, As, Hg, Cr, Ni) and two classes of pesticide residues (organochlorines and pyrethroids) in six widely used medicinal plant species—Mentha piperita, Salvia officinalis, Glycyrrhiza glabra, Matricaria chamomilla, Artemisia absinthium, and Taraxacum officinale—collected from three production regions: the Fergana Valley, Tashkent Region, and Jizzakh Region. Analysis employed inductively coupled plasma mass spectrometry (ICP-MS) for heavy metals and gas chromatography-mass spectrometry (GC-MS) for pesticide residues. Human health risks were assessed using Target Hazard Quotient (THQ), Hazard Index (HI), and Carcinogenic Risk (CR) models. All samples complied with Uzbekistan's SanPiN 0366-19 maximum permissible concentrations for Pb, Cd, As, and Hg. However, Taraxacum officinale samples from the Tashkent ring road area showed elevated Pb concentrations (6.78 ± 0.42 mg/kg), approaching the regulatory limit. Chromium and nickel were detected at higher concentrations in samples from industrially influenced sites. Pesticide residues were largely below detection limits, with only trace fenvalerate and chlorpyrifos detected in a few samples. Health risk assessment revealed THQ values below 1 for all metals in both adults and children, with HI ranging from 0.42 to 0.78, indicating acceptable non-carcinogenic risk. However, the carcinogenic risk of arsenic (3.2 × 10⁻⁵) exceeded the USEPA threshold (1 × 10⁻⁶), warranting continuous monitoring. This study provides foundational data for quality standard development and recommends establishing routine monitoring systems for medicinal plant safety in Uzbekistan.