SAN DIEGO -- Cigarettes are deadly not only for humans, but also for fish, according to San Diego State University researchers who want cigarettes butts labeled as toxic hazardous waste, it was reported Monday.

Researchers believe the label would help change the public's perception about the harm cigarette butts cause the environment and prompt more rules to reduce their presence, The San Diego Union-Tribune reported.

The San Diego scientists are scheduled to present their findings in Philadelphia Monday at the 137th annual meeting of the American Public Health Association. The researchers also submitted their results for publication in a peer-reviewed journal, according to the newspaper.

"It's another way of looking at cigarettes as a societal hazard," Tom Novotny, an SDSU public health professor, said in remarks reported by the Union- Tribune. "If we reframe the butts as toxic hazardous waste, that adds another opportunity to change the social acceptability of smoking."

Rick Gersberg, a fellow SDSU professor of public health, helped design an experiment in which he let smoked filters soak in containers of water for 24 hours. Then he put fish in the polluted water and monitored them for five days, according to the newspaper. Half the fish died, Gersberg said.

The effort is not without critics. Robert Best, regional director of the smokers' rights group Citizens Freedom Alliance in Ventura County, told the Union-Tribune that he is skeptical.

"This is just another attack on smokers and an attack on the entire tobacco industry, including farmers and distributors, in the midst of an economic crisis," Best said. "We already have littering laws in the state of California that say you cannot throw any trash out on the ground or in the waterways."