Electroencephalographic and behavioral effects of intracerebroventricular or intraperitoneal injections of toxic honey extract in adult Wistar rats and GAERS

Risks for human health related to the presence of grayanotoxins in certain honey

The European Commission asked EFSA for a scientific opinion on the risks for human health of the presence of grayanotoxins (GTXs) in 'certain honey' from Ericaceae plants. The risk assessment included all structurally related grayananes occurring with GTXs in 'certain' honey. Oral exposure is associated with acute intoxication in humans. Acute symptoms affect the muscles, nervous and cardiovascular systems. These may lead to complete atrioventricular block, convulsions, mental confusion, agitation, syncope and respiratory depression. For acute effects, the CONTAM Panel derived a reference point (RP) of 15.3 μg/kg body weight for the sum of GTX I and III based on a BMDL10 for reduced heart rate in rats. A similar relative potency was considered for GTX I. Without chronic toxicity studies, an RP for long-term effects could not be derived. There is evidence for genotoxicity in mice exposed to GTX III or honey containing GTX I and III, showing increased levels of chromosomal damage. The mechanism of genotoxicity is unknown. Without representative occurrence data for the sum of GTX I and III and consumption data from Ericaceae honey, acute dietary exposure was estimated based on selected concentrations for GTX I and III reflecting concentrations measured in 'certain' honeys. Applying a margin of exposure (MOE) approach, the estimated MOEs raised health concerns for acute toxicity. The Panel calculated the highest concentrations for GTX I and III below which no acute effects would be expected following 'certain honey' consumption. The Panel is 75% or more certain that the calculated highest concentration of 0.05 mg for the sum of GTX I and III per kg honey is protective for all age groups regarding acute intoxications. This value does not consider other grayananes in 'certain honey' and does not cover the identified genotoxicity.

Mad honey: uses, intoxicating/poisoning effects, diagnosis, and treatment

Honey has been used as a folk medicine since 2100 BC; however, mad honey is different from normal natural or commercially available honey as it is contaminated with grayanotoxins, which leads to intoxication/poisoning upon consumption. Grayanotoxin is generally found in Rhododendron genus (family: Ericaceae) and is extracted by bees from nectar and pollens of flowers. Mad honey has been commonly used as an aphrodisiac (sexual stimulant), in alternative therapy for gastrointestinal disorders (peptic ulcer disease, dyspepsia, and gastritis), and for hypertension for a long time. Grayanotoxin acts on sodium ion channels and muscarinic receptors, leading to cardiac disorders (hypotension and different rhythm disorders including bradycardia, bradydysrhythmias, atrial fibrillation, nodal rhythm, atrioventricular block, and complete atrioventricular block) and respiratory depression. Patients may also exhibit any one symptom out of or combination of dizziness, blurred vision, diplopia, nausea, vomiting, vertigo, headache, sweating/excessive perspiration, extremity paresthesia, impaired consciousness, convulsion, hypersalivation, ataxia, inability to stand, and general weakness. Mad honey intoxication is diagnosed with honey intake history before the appearance of the signs and symptoms (clinical presentation), and the treatment is symptomatic. Prompt treatment includes intravenous infusions of atropine sulfate and fluids (saline infusions or simultaneous infusion of saline with atropine sulfate) if the patient presents bradycardia and severe hypotension. In case of a complete atrioventricular block, a temporary pacemaker is employed. Except for a single case from Lanping County (Southwest China), the prognosis for mad honey intoxication is very good, and no fatalities have been reported in modern medical literature excluding a few in the 1800s. Although fatalities are very rare, mad honey ingestion may still lead to arrhythmias, which can be life-threatening and hard to recognize. This article provides a brief introduction to honey, mad honey and its uses, the effects of mad honey intoxication/poisoning, and its diagnosis, prognosis, and treatment.

Honey has been used as a folk medicine since 2100 BC; however, mad honey is different from normal natural or commercially available honey as it is contaminated with grayanotoxins, which leads to intoxication/poisoning upon consumption.