OIA2007 TOXICITY WHO GUIDELINE

Self-treatment risk

Herbal medicines are widely available without prescription and marketed as "side effect-free," leading to inappropriate self-medication.

Unqualified practitioners

Unlicensed individuals may prescribe unverified remedies, worsening health outcomes.

Sub-standard products

Products may have incorrect or absent active ingredients, or harmful adulterants due to poor manufacturing controls.

Improper storage issues

Loss of potency or contamination can occur if plant materials are stored improperly (e.g., exposure to moisture, pests).

Adulteration

Some products are mixed with other plants or synthetic drugs without disclosure, leading to toxicity or interactions.

Environmental contamination

Herbal products may contain pollutants like ozone, NO₂, CO, particulate matter, molds, and infectious microbes.

Contaminant entry points

Can enter during cultivation, harvesting, drying, or storage due to poor hygiene or environmental exposure.

Pesticide residues

Result from agricultural practices; may accumulate in the plant material.

Heavy metal contamination

Caused by industrial pollution — arsenic, mercury, lead, cadmium are common culprits.

Radioactive contamination

Rare, but possible post-nuclear accidents; must be monitored per IAEA and WHO guidelines.

Potentiation of drug toxicity

Herbs can increase the toxicity of conventional drugs by affecting metabolism

Pharmacokinetic interactions

Alterations in drug absorption, distribution, metabolism (especially via CYP enzymes), or excretion.

Pharmacodynamic interactions

Herbs may antagonize or synergize with drug action (e.g., St. John’s Wort reducing warfarin efficacy).

Definition of quality control

Assessment of identity, purity, and content of herbal medicines, or evaluation of manufacturing processes.

Identity

Confirms correct plant species and plant part used.

Purity

Ensures absence of contaminants like other herbs, chemicals, microbes, or heavy metals.

Content or assay

Measures active constituent concentration within specified limits.

Microscopic evaluation

Visual (color, odor, fracture) and microscopic (tissue features) assessment of raw drug.

Foreign matter

Includes non-plant material (e.g., stones, soil, animal waste) or incorrect plant parts.

Foreign matter detection methods

Manual picking or Lycopodium spore method for quantification.

Total ash

Measures total residual material after incineration (includes plant and non-plant residues).

Acid-insoluble ash

Estimates silica (sand/soil) by boiling total ash with HCl and incinerating the residue.

Water-soluble ash

Difference between total ash and residue left after washing with water; measures water-soluble inorganic salts.

Common heavy metals tested

Mercury, lead, cadmium, copper, and arsenic.

WHO limits (ppm)

Arsenic: 10 ppm, Mercury: 1 ppm, Lead: 10 ppm, Cadmium: 0.3 ppm.

Testing techniques (heavy metals)

Atomic absorption spectrophotometry (AAS), inductively coupled plasma (ICP), and neutron activation analysis (NAA).

Sources of microbial contamination

Improper harvesting, handling, drying, or storage conditions.

Aflatoxins

Toxins from Aspergillus flavus and A. parasiticus; highly carcinogenic.

USP limit for aflatoxins

Aflatoxin B₁ ≤ 5 ppb; total aflatoxins ≤ 20 ppb.

Detection methods for aflatoxins

Primarily chromatographic techniques (e.g., HPLC, TLC).

Herbal drugs and pesticides

Common due to spraying and soil treatment; concern for chronic toxicity.

WHO pesticide testing guideline

Tests for general pesticide groups (e.g., organochlorine, organophosphorus), not individual chemicals.

European Pharmacopoeia standard

Aligns with WHO guidelines for evaluating broad pesticide categories.

Causes of radioactive contamination

Environmental fallout from nuclear accidents or improper plant sourcing.

Governing bodies

Guidelines by IAEA, WHO, and FAO must be followed for plant safety assessments.

Most common toxicity causes

Self-medication, product adulteration, improper dosing, and interactions with modern drugs.

Population at higher risk

Immunocompromised individuals, children, pregnant women, elderly — more vulnerable to herbal toxicity.

Public health risk

Unregulated use of contaminated herbal products can result in outbreaks of poisoning or chronic diseases.

Consumer awareness

Necessary to improve understanding of herbal product risks and ensure proper use under guidance.

Global harmonization

International guidelines aim to standardize herbal medicine safety through strict quality control and regulation.