After a long battle with Yale’s administration, some New Haven residents are still questioning the University’s use of pesticides, which they said have infiltrated surrounding neighborhoods.

Laura Cahn, who lives on Cleveland Avenue bordering Yale’s athletic fields, has been leading efforts against the University’s pesticide use for several years. Cahn said that in the past Yale has sprayed athletic fields, residential college sidewalks, city sidewalks and tree beds with pesticides. This year she noticed pesticides were being sprayed on either side of Central Avenue and that the workers were not wearing any protective gear. Cahn and other neighbors are concerned that these chemicals are jeopardizing local water and posing public health threats to neighbors, workers and students.

“I’ve smelled that smell before,” Cahn said about the pesticides which she said were sprayed this past August.

The University responded that Yale’s actions are legal. University Spokesman Tom Conroy said that Yale only uses approved products and methods and that there have been no violations of environmental regulations.

Even if the University is using approved amounts of pesticides, small mistakes in their application could lead to problems for the environment, said Joel Bader, the national coordinator for Aquatic Animal Health.

“While the science shown to the public says that the use of proper amounts of pesticides are not harmful and produce the desired results, every year there is improper application,” Bader said.

Moreover post-application rain frequently flushes pesticides into the watershed, impacting wildlife and threatening public health, Bader added.

Bader said more science is needed both to better understand the effects of chemicals on public health and the surrounding ecosystems and to explore alternative, less risky methods of maintaining lawns and fields.

Jeanne Dubino, Cahn’s neighbor was less critical of Yale. She said Yale has responded to her concerns by using fewer pesticides and informing neighbors of which pesticides it uses. Yet Dubino said she is still concerned that pesticides, though considered safe now, will have unforeseen consequences.

Dubino said she would ultimately like to see Yale stop using pesticides all together.

As one of the world’s leading universities, Dubino said Yale should ban pesticides in order to be a role model in environmental policy.

In the meantime, Cahn said she would like Yale to inform neighbors before they apply pesticides and to post pesticide flags on each gate in the neighborhood.

Fields in Branford and Cheshire have already banned pesticides, said Jerry Silbert, the head of the Watershed Partnership and consultant in the conversion of Branford and Cheshire.

Though in the beginning pesticide-free field maintenance is more expensive than using such chemicals, the cost is offset in the end, Silbert said. He explained that while pesticide-free methods require more grass seeds, that cost is offset because the grass does not need to be mowed as often.

“Many people used to pesticides don’t want to switch [but] if people are motivated to do it correctly … you can get very few weeds without pesticides.”

As of now the EPA does not mandate the companies disclose the inert ingredients in their products unless they are considered “hazardous”.