EUROPE – The European Food Safety Authority (EFSA) has estimated that 0.05 mg/kg is the highest concentration for grayanotoxins, a natural compound found in honey, that would not negatively affect honey consumers.

EFSA conducted a risk assessment on the risks to human health posed by the presence of grayanotoxins in honey following a request from the European Commission.

The study included all structurally related grayananes found in honey and other foods alongside grayanotoxins.

Grayananes are a type of chemical produced by certain flower species. When consumed, they can have an impact on a person’s heart, neurological system, and muscles.

Symptoms from ingesting grayananes include atrioventricular block, seizures, confusion, agitation, syncope, and respiratory depression.

The substance can accumulate in honey produced by honeybees that collect the nectar of flowering plants containing grayananes.

Rhododendron ponticum, R. luteum, and R. ferrugineum are the three most significant species of grayanane-producing plants used in commercial honey production.

These flower species can be found in the Pyrenees, the Alps, and Turkey.

In the French island of La Réunion, non-Rhododendron honey from Agarista salicifolia has also been linked to acute grayanane intoxications in people.

Although certain acute intoxications have also been attributed to honey from other countries, acute intoxications documented in recent decades from European countries are primarily linked to imported honey from Turkey or Nepal.

Thus far, there have been no cases of intoxication documented for honey from the EU.

There are about 20 grayananes that have been found in or linked to honey.

Grayananes have been demonstrated to have short-term effects on the circulatory system, respiration rate, and nervous system in investigations on acute animal toxicity.

Reduced blood pressure and bradycardia stood out among these as the signs of intoxication in people the most.

Grayanotoxin levels in Rhododendron honey that have been linked to acute poisoning in humans have also been reported to range from 0.5 to 54 milligrams per kilogram (mg/kg) and range from 5-150 grams of the product.

In many cases, the nervous and cardiovascular systems were affected by symptoms that appeared suddenly.

Symptoms of poisoning remained for a few hours to a few days, with a normal recovery time of 1-2 days.

Using the margin of exposure (MOE) technique, which is a ratio between the dose at which demonstrable adverse effects are detected and the level of exposure to a drug for a specific population, EFSA was able to evaluate the health risk posed by grayanotoxins in honey.

A ratio of 10,000 or above denotes a low concern for consumers.

Grayanotoxins in honey were calculated to have MOEs under 100, which raises questions about their potential for acute toxicity.

According to EFSA, the maximum amount of grayanotoxins in honey that won’t affect children’s heart rates and blood pressure is 0.05 mg/kg, and the agency is 75% confident that this level is safe for all age groups.

Only a small number of the more than 1,000 intoxication cases that were located in published literature, however, included quantitative data on the amount of grayananes in the honey.

To this end, EFSA notes that further study is needed to improve the risk assessment for humans and lower uncertainties because there is generally a shortage of published data.

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