The Danger of Pesticides

LONDON — European food regulators said on Tuesday that a class of pesticides linked to the deaths of large numbers of honey bees might also harm human health, and they recommended that the European Commission further restrict their use.

Dead bees in an anti-pesticide demonstration in Bulgaria. All neonicotinoid pesticides could be affected by Europe’s stance.

The commission, which requested the review, has already taken a tougher stance than regulators in other parts of the world against neonicotinoids, a relatively new nicotine-derived class of pesticide. Earlier this year, some were temporarily banned for use on many flowering crops in Europe that attract honey bees, an action that the pesticides’ makers are opposing in court.

Now European Union regulators say the same class of pesticides “may affect the developing human nervous system” of children. They focused on two specific versions of the pesticide, acetamiprid and imidacloprid, saying they were safe to use only in smaller amounts than currently allowed. Imidacloprid was one of the pesticides placed under a two-year ban this year.

The review was prompted by a Japanese study that raised similar concerns last year.

Imidacloprid is one of the most popular insecticides, and is used in agricultural and consumer products. It was developed by Bayer, the German chemicals giant, and is the active ingredient in products like Bayer Advanced Fruit, Citrus & Vegetable Insect Control, which can be purchased at stores internationally, including Home Depot in the United States.

Acetamiprid is sold by Nisso Chemical, a German branch of a Japanese company, though it was developed with Bayer’s help. It is used in consumer products like Ortho Flower, Fruit & Vegetable Insect Killer.

The action by European regulators could affect the entire category of neonicotinoid pesticides, however.

James Ramsay, a spokesman for the European Food Safety Authority, which conducted the review, said the agency was recommending a mandatory submission of studies related to developmental neurotoxicity “as part of the authorization process in the E.U.”

“We’re advising that all neonicotinoid substances be evaluated as part of this testing strategy, providing that they show a similar toxicological profile to the two substances we’ve assessed in this opinion,” he said.

Research by the Environmental Protection Agency in the United States has also raised concerns about the effect of the pesticides on honey bees, but the agency has not yet seen enough evidence to take action. The E.P.A. did not immediately have a response on Tuesday.

Bayer sharply disputed the European assessment on Tuesday.

“Imidacloprid has no developmental neurotoxicity potential in humans,” Richard Breum, a spokesman for Bayer CropScience, said in a statement. He raised questions about the Japanese research, which he said “reports investigations in rat cell cultures, i.e. in an artificial system.”

“Bayer CropScience has also evaluated the publication and can confirm that few conclusions can be drawn from it,” he added.

Bayer’s stock fell slightly in European trading Tuesday. Bayer, along with two competitors, Syngenta and BASF, is already disputing the existing limited ban on neonicotinoids in the European courts.

A spokesman for Nisso Chemical could not be reached Tuesday evening in Europe.

In a statement, the European Food Safety Authority said it “recognizes the available evidence has limitations and recommends further research be carried out to provide more robust data,” but added that “health concerns raised in the review of the existing data are legitimate.”

The matter now goes before the European Commission, the executive arm of the European Union. It will probably take several months before any action is taken, as was the case when the food safety authority recommended action to safeguard bee populations.

Frédéric Vincent, a spokesman for the commission, said the process of reviewing the findings would allow Bayer and Nisso to comment on the recommendation.

Previously, neonicotinoids have been seen by many scientists as a potential culprit in unusually large die-offs of honey bees in North America and Western Europe that were first noticed in 2006. Bayer attributes the deaths to the varroa mite, a parasite that has long been a threat to bees.

But in October, a study in the Proceedings of the National Academy of Sciences journal examined how a neonicotinoid made by Bayer “adversely affects the insect immune response and promotes replication of a viral pathogen in honey bees bearing covert infections.”