Evaluation of Heavy Metals and Microbial Contamination in Herbal Medicines Used for Chronic Illnesses in Nairobi Metropolis

The World Health Organization estimates that 70-80% of the world’s population uses herbal medicines for their primary health care needs. Herbal medicines may be contaminated with toxic metals, microbes and pesticide residues among other contaminants. In spite of their popularity and immense contribution to the primary health care, many African countries lack or have insufficient quality control systems to assure the safety of these products. This study sought to evaluate marketed herbal products for two important quality parameters, heavy metals and microbial contamination, in Nairobi metropolis that comprises of Nairobi City County and sections of Kiambu, Kajiado and Machakos Counties. Experimental Herbal medicine samples used for the management of chronic illnesses namely diabetes, human immunodeficiency virus/acquired immune deficiency syndrome, rheumatoid arthritis, peptic ulcer disease, tuberculosis, cancer and hypertension were obtained from pharmacies, open-air markets and supermarkets within Nairobi metropolis. Heavy metals namely lead, cadmium, mercury and arsenic were quantitatively determined using inductively coupled plasma mass spectrometry. Microbial analysis was performed according to the British pharmacopeia, 2017 specifications for herbal medicines. Principal component analysis was performed in order to detect potentially harmful herbal medicines using Origin Pro 9.1 software (OriginaLab Corporation, MA, USA) while quantitative risk assessment was conducted to evaluate the potential public health risk posed by consumption of herbal medicines using target quotient and cancer risk methodology as elaborated by the United States Environmental Protection Agency. Results and Discussion A total of 89 herbal products were sampled for this study. A large proportion of the samples (42, 47.2%) were collected from Nairobi City County because it is the core distributive centre of the other metropolis regions. The remaining 47 samples (52.8%) were from the other three counties. Among the 89 samples, 55 ...