An article in today’s Seattle Times reports that three King County residents were recently affected by foodborne toxins. Unfortunately, one came from a sample of local honey.
According to the article a man became ill after eating a portion of honey he had purchased at a local farmer’s market. He reported vomiting and “intestinal difficulties” which began about an hour after consuming the honey. The honey sample was sent to the state department of agriculture, but tests were unable to confirm the presence of a toxin.
However, the man’s symptoms led officials to believe the honey contained grayanotoxin, a material found in rhododendron plants. The condition, also known as “rhododendron poisoning” or “honey intoxication,” is well-documented but rare.
Grayanotoxin is a naturally-occurring neurotoxin found in the nectar of rhododendrons. According to Wikipedia, symptoms include salivation, perspiration, vomiting, dizziness, and low blood pressure. The condition is rarely fatal and usually abates within 24 hours.
In a cruel hit to small honey producers, the author of the Seattle Times piece writes that local honey is much more likely to contain toxic levels of grayanotoxin than honey coming from large commercial producers because commercial producers mix honeys from many sources–a variation on “dilution is the solution to pollution.”
The ABC & XYZ of Bee Culture mentions that both the nectar and pollen of rhododendron are poisonous to bees as well as humans. Although the toxin can kill the bees, it is well diluted with water in the nectar. But as the water is driven from the nectar to produce honey, the grayanotoxin is concentrated to poisonous levels.
I didn’t find any references to how frequently honey intoxication occurs but the numbers must be low. The Puget Sound area is overrun with rhododendrons–in fact it is the Washington state flower–but few cases of poisoning are reported. My own property is loaded with both honey bees and rhododendrons but I have never seen a honey bee on a rhododendron flower. These observations lead me to believe that rhododendron is not a preferred forage for honey bees and they probably collect it only in rare circumstances when other more favorable blooms are not available.
If you are interested in foodborne toxins, the Seattle Times article is interesting. Besides honey intoxication you can read about toxic squash syndrome and combroid fish poisoning. So, what’s for dinner?
Rusty
Rhododendron ten feet from a busy hive
OK —- related to this, the Slow Foods Ark of Taste includes Italian rhododendron honey. I have friends who brag about eating this and my reaction has always been “omg poison!” So, are their rhododendrons different? Or is the standard for poisoning not so high in heirloom foods? I have been trying to figure this out for like, six months so I’m really glad you wrote about this.
Jess,
Wikipedia says, “Honey from Japan, Brazil, United States, Nepal, and British Columbia is most likely to be contaminated with grayanotoxins, although very rarely to toxic levels.” Also, The ABC & XYZ of Bee Culture says that there are several species and hybrids of rhododendron, including R. ponticum, that produce the toxin. So it looks like just certain species are bad and those species don’t seem to have come from Italy.
The bees must be able to tell the difference, at least most of the time. Interesting. I’d like to try Italian rhododendron honey.