At the height of the bug season, officials in New York are warning consumers not to use insect repellents with high levels of the chemical DEET because of health risks. They are also proposing that such products be banned.
DEET-related health problems include skin rashes and scarring in adults and, in a few cases, reports of neurological problems in children. A ban would affect products that are more than 30 percent DEET.
New York is the first state to propose such a ban. Makers of the repellent oppose a ban.
"Our position is that there should be no restriction on DEET because these are beneficial products," said Barbara Jorgensen, a spokeswoman for S. C. Johnson & Son of Racine, Wis., which makes Off.
DEET is in virtually every chemical repellent in concentrations ranging from 7 percent to 100 percent. It is listed on labels as N,N-diethyl-m-toluamide. Both Maximum Strength Off and Maximum Strength Cutter, which is made by Miles Inc. of Elkhart, Ind., are 100 percent DEET.
New York officials say repellents with stronger concentrations are no more effective than those with lower concentrations and that the stronger ones pose added health risks.
They said they decided to act because manufacturers have begun to promote stronger DEET formulas to cater to a public fearful of Lyme disease, which is caused by an organism carried by deer ticks.
"We don't think 50 percent DEET is any more effective than 30 percent, certainly not to justify the added health risk," said William Stasiuk, director of the Center for Environmental Health in the New York State Health Department.
State officials also say there is not enough data to judge how well strong DEET formulas work against the deer tick. Repellent manufacturers are carrying out new efficacy studies and some of that data may be presented today at a public hearing on the ban, which has been proposed by the Department of Environmental Conservation, which regulates pesticides.
Major producers of repellents say DEET, which has been used since the 1950s, is effective against many insects and is safe when used as directed. Ms. Jorgensen said that lower DEET formulas could lead to increased cases of Lyme disease.
New York State officials do not deny that DEET repels deer ticks. But they say they have seen little data, even from manufacturers, to judge what concentrations work best.
"Most of the efficacy information on DEET relates to mosquito repellency," said Anthony Grey, a scientist in the Health Department. "There is not a lot of information on ticks."
In one deer tick study reviewed by New York officials, a 30 percent DEET formula sprayed onto clothing was 92 percent effective. In a separate study, a 33 percent DEET product in a controlled-release form was only 17 percent effective.
The Chemical Specialties Manufacturers Association, a trade group in Washington, says that makers of repellents believe that a 40 percent concentration of DEET is necessary to protect against ticks.