Herbal medicine use in Ekiti state, Nigeria: epidemiological study and analysis of toxic constituents

Herbal medicines (HM) use and popularity as a form of complementary and alternative medicine (CAM) continue to increase globally. However, public health and safety concerns also continue to grow. Contamination of HM samples with chlorinated pesticides and heavy metals has been reported, likewise adulteration with prescription medication. In this research, an interdisciplinary method drawn from public health and forensic chemistry was adopted. It examined the knowledge and use of HM in Ekiti state, Southwest Nigeria, with a population of over two million. A survey was used to explore public knowledge, use, and perception of HM effectiveness and safety. Textual analysis, inferential and descriptive statistics were used to analyse survey data. Hospital data from the state was also examined to determine HM related casualty and fatality figures over a period of 5 years (2010 to 2014) and the findings were compared with the survey findings. Ten commonly used HM identified in the survey were then analysed for the possible presence of prescription medicines and heavy metals using Gas Chromatography-Mass Spectrometry (GC-MS) and Inductive Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) respectively. Findings of this research showed that 85.0% of the respondents have used HM in the last two years. Although 57.0% had concerns about the safety of uncertified HM, 37.3% used them anyway, while 31.9% used both uncertified and certified HMs. The use of HM (85.0%) was attributed to its effectiveness by 39.6% of users; while poor service delivery was the primary reason 45.2% of respondents did not use the orthodox health system. There was a significant association between HM use and the age, gender, level of education, religion, annual income and occupation of respondents, using the Chi-square analysis at a significance level of 0.05. Hospital records of patients (n=94,323) showed a small number of HM associated paediatric admissions (0.5%), adult admissions (0.06%), paediatric deaths (3.2%) and adult deaths (0.2%). Analysis of all the studied HMs showed that cadmium and copper were detected at above World Health Organization (WHO) permissible limits and one of the samples also had lead and zinc above the limit. However, none of the target pharmaceutical compounds was detected in the HM samples. This research investigated the issues surrounding the use of HMs, their potential toxicity, casualties, and fatalities. The onset and progression of some medical problems as highlighted in this research may be connected with exposure to heavy metals when present above permissible limits. Additionally, even when metals are present below permissible limits, prolonged exposure may result in accumulative toxicity. Therefore this study highlights a major public health concern and a need to monitor and control HMs through appropriate legislative changes. This is the first multidisciplinary investigation of HMs in the study population and the wider public.