Title:Risk Assessment of Toxic Heavy Metal Exposure through Medicinal Herbs in the Indian State of West Bengal
Volume: 4
Author(s): Avijit Hazra*, Alok Kumar Hazra, Swapan Kumar Jana and Tapas Kumar Sur
Affiliation:
- Department of Pharmacology, Institute of Post Graduate Medical Education and Research, Kolkata, India
Keywords:
Lead, arsenic, cadmium, mercury, medicinal herb, medicinal plant, risk assessment, atomic absorption spectrophotometry.
Abstract:
Background: More than 80% of the world's population uses herbal remedies in some
form. Heavy metal contamination and the attendant health risks of Indian herbal medicines are
not adequately documented.
Objective: This study aimed to investigate the health risks associated with four common heavy
metal contaminants, namely lead, arsenic, cadmium, and mercury, present in raw medicinal herbs
cultivated or growing wild in the West Bengal state of India.
Methods: A total of 197 raw herbs obtained from herbal medicine practitioners or wild plant
collectors from 16 districts spread across 3 geographical zones (south, central, north) of West
Bengal were analyzed. In accordance with AOAC specifications, all samples were dried in a hot
air oven, ground into a coarse powder, and then processed and analyzed for heavy metals through
atomic absorption spectrometry. The mean concentrations were estimated along with standard
deviations, overall, zone-wise, and according to the botanical part tested. The standardized human
health risk indices were calculated from the results.
Results: Significant amounts of heavy metals were found in the herb samples analyzed in the
order: lead in 150 samples (76.1%), arsenic in 84 (42.6%), cadmium in 77 (39%), and mercury
in 47 (23.8%). Central zone samples had the highest concentrations of lead (10.06 μg/g), arsenic
(0.62 μg/g), and cadmium (0.54 μg/g), while the greatest amount of mercury (0.08 μg/g) was
obtained in herbs from South zone. There were also considerable variations with respect to the
source of the botanical part. Lead and cadmium concentrations showed a significant positive correlation
(r = 0.588). Although risk assessment using standardized measures indicated some risk,
the human Hazard Index (HI) was less than 1 for all metals, indicating that it was mostly safe to
use the herbs in the short-term. However, the risk of health issues from prolonged use still remains.
Conclusion: Significant contaminations were identified, but exposure would mostly be within
acceptable risk levels at present. However, since risk would be cumulative over time, programs
need to be in place to monitor pharmaceutical herb safety, identify local sources of pollution, and
take appropriate remedial action.
