Food safety eye regulation of tutin poisons in honey

Food safety experts are scrambling to obtain quantities of the toxins tutin and hyenanchin -- implicated in the Easter honey poisonings -- so that they can pin down their exact toxicity and possibly set regulatory limits.

Specific chemical standards will allow regulators to impose testing on commercial honey if necessary.

At present, regulators only require apiarists to record information on the risk of tutu toxins entering their honey and the actions they have taken to mitigate the risk. Few checks are made on the records until after an outbreak of poisoning.

Test results released today confirmed that the two tutu toxins were in comb honey from the Coromandel Peninsula eaten by 22 people who reported falling ill.

Tutin toxin is difficult to identify in the human body, but Food Safety Authority (NZFSA) animal products manager Jim Sim said the confirmation came through testing of leftovers provided by people who fell ill after eating the honey from Whangamata's Projen Apiaries at Easter.

High levels of both the toxin tutin and its derivative hyenanchin were found.

Tests on guinea pigs and rats 40 years ago showed tutin can be lethal at very low levels, as small as 0.01mg/kg, but some scientists have said it is likely that humans are actually more susceptible to the toxins than animals. In rats, hyenanchin is lethal at doses of 0.09mg/kg.

Tutin can kill by acting on the central nervous system, causing epileptic-like convulsions, affecting breathing and causing faecal and urinary incontinence, and loss of memory in survivors, according to Poisonous Plants in NZ, by Henry Connor.

Test results combined with the reported symptoms in the Easter outbreak were "consistent with acute poisoning from tutin and hyenanchin," Mr Sim said.

Toxic honey is caused when bees feed on "honeydew" secreted from the rear end of tiny sap-sucking vine-hopper insects feeding on the tutu plant. The honey is extremely dangerous and outbreaks of honey poisoning have been documented for over a century, mainly in the Coromandel, eastern Bay of Plenty and Marlborough Sounds during hot dry summers, when vine hopper numbers are high.

Beekeepers are supposed to remove their hives from risk areas when toxic honeydew is abundant.

About 20 packages of potentially toxic comb honey branded as Wentworth Valley or Moana Point brands are still unaccounted for, and Mr Sim said they should be handed in to their nearest public health unit.

NZFSA is testing honey from other companies and had so far found no evidence of tutin, though hyenanchin at levels well below those that might result in illness have been detected. The poisons usually only cause problems in comb honey, because they are heavily diluted when apiarists pool "suspect" honey with honey collected from other areas.

NZFSA has focused continuing sampling on honey from areas where those positive samples were obtained, and has been checking harvest records.

"Right now, what we need is more information about the affected areas and amount of contamination," he said. Mr Sim said no decision has yet been made on whether to prosecute the beekeeper.