Three-quarters of the world’s honey contains nerve agent pesticides that pose a potential health hazard to humans, a study suggests.
Scientists tested 198 honey samples from six continents – and 75% of them contained at least one type of neonicotinoid chemical, which is also harmful to bees.
Two-fifths of the samples contained two or more varieties of the pesticides, and 10% held residues from four or five.
Concentrations of pesticides were highest in European, North American and Asian samples.
Environmental campaigners are now demanding a “complete and permanent” ban of neonicotinoids on farm crops in Europe.
Experts have described the findings as “alarming”, “sobering” and a “serious environmental concern” – but stressed most of the pesticide levels in honey were well below the safe limits for human consumption.
Dave Goulson, professor of biology at the University of Sussex, said: “Beyond doubt… anyone regularly eating honey is likely to be getting a small dose of mixed neurotoxins.
“In terms of acute toxicity, this certainly won’t kill them and is unlikely to do measurable harm.
“What we don’t know is whether there are long-term, chronic effects from lifetime exposure to a cocktail of these and other pesticides in our honey and most other foods.”
Professor Goulson added that, for practical reasons, it is “impossible to do a proper experiment to test this”.
Neonicotinoids are neuroactive chemicals similar to nicotine and have been highly effective at protecting crops from pests – especially aphids and root-eating grubs – and can either be sprayed on leaves or coated on seeds.
This can allow them to infiltrate every part of the growing plant.
Research shows that, under controlled conditions, the chemicals are toxic to honey bees and bumblebees – causing brain damage that can affect learning and memory, as well as impair their ability to forage for nectar and pollen.
Results from the world’s largest bee colony field trial in three European countries in June found that neonicotinoid exposure reduced the survival of both honey and wild bees in the UK and Hungary.
The research, published in the Science journal, comes as the European Commission discusses whether to make the ban permanent or more wide-ranging.
A total ban would have a huge impact on cereal growers in the UK.