Montgomery County became the country’s first major locality Tuesday to ban the use of cosmetic pesticides on private lawns, concluding that the time-honored right of suburbanites to maintain pristine green, weed-free yards was superseded by a body of scientific evidence linking the widely-used products to cancer.

After three hours of sometimes emotional debate, which included members recounting their own personal and family experiences with cancer, the County Council voted 6-to-3 to impose the ban on the chemicals--all deemed safe by the EPA when used appropriately--effective at the beginning of 2018. The measure excludes agricultural land, gardens and golf courses and does not prohibit the sale of lawn pesticides within the county.

Nor is there a specific enforcement provision in the law that empowers county inspectors to scrutinize homeowners’ lawns for pesticide content. Like many county regulations, it will depend on citizen complaints. But advocates discounted the lack of regulatory teeth and said the bill will serve as a valuable tool to educate residents on organic alternatives.

The council’s action puts the county on a very short list of jurisdictions that have passed similar bills: Takoma Park, Md. and Ogunquit, Maine, an oceanside community with a year-round population of about 1,300.

“I believe we are acting in the interests of public health today,” said Council President George Leventhal (D-At-Large), the bill’s chief sponsor, who introduced the measure nearly a year ago.

Opponents of the bill, including homeowners and the lawn care and chemical industries, protested what they called an unwarranted government intrusion into a traditional homeowner right.

“I think this is a case of politics trumping science and fact,” said Karen Reardon, vice president of public affairs for RISE (Responsible Industry for a Sound Environment) a national trade association for pesticide manufacturers and distributors.

Leventhal had to make a major concession to achieve a winning margin, agreeing to exempt the county’s nearly 300 athletic playing fields after opposition from the soccer community and other sports enthusiasts. The bill does, however, establish a five-field pilot program using organic products. It tasks the county’s parks department to develop a plan to make all playing fields pesticide free by 2020.

The council’s two-thirds majority vote shields the measure from veto by County Executive Isiah Leggett. He voiced concerns Tuesday about several aspects of the bill, including language that appears to mandate pesticide-free playing fields by 2020 no matter what the pilot program shows.

“To me that’s troubling,” Leggett said.

The bill is a vivid example of the geographic divide in county politics, pitting a progressive, left-leaning south against more moderate areas in the center and north. Not coincidentally, three of the six votes in support of the bill came from council members who reside in Takoma Park: Marc Elrich (D-At-Large), Hans Riemer (D-At Large) and Leventhal. The southeastern Montgomery community was the center of a grassroots campaign to pass a countywide version of the bill.

Two of the bill’s three “no” votes come from the central and northern parts of the county, where many homeowners oppose the bill: Craig Rice (D-Germantown) and Sidney Katz (D-Gaithersburg).

Pesticide regulation is usually a federal and state responsibility. Earlier this year the council heard testimony from the Maryland and the federal EPA officials, who said pesticides are rigorously tested and safe when used appropriately.

But proponents argued that the government can’t be relied upon to protect citizens from toxins in the environment. They cited, among studies, a 2013 report by the Government Accountability Office and the Natural Resources Defense Council, that said thousands of pesticides were approved for use without being fully tested for hazards to human health.

Advocates said it was irresponsible to wait for scientists to establish a complete causal link between pesticides and cancer, contending that the record was clear enough. They pointed to a 2012 report from the American Academy of Pediatrics that said the data “demonstrates associations” between childhood pesticide exposure and cancer, along with decreased cognitive skills and other disorders. Yet the study stopped short of favoring a sweeping ban, saying that more research is needed.

That was the principal argument of Council member Roger Berliner (D-Bethesda) who unsuccessfully offered a substitute bill that exempted private land from the ban.

Berliner’s version of the legislation banned pesticides on county property, near daycare centers, playgrounds and waterways. But he contended that most county residents were unprepared for a sweeping ban.

“It would be like going from zero to sixty in a nanosecond,” said Berliner, a legislator with a strong environmental record who added that he “hated” voting against the bill.

The most memorable moments of the debate came when Council members Nancy Navarro (D-Silver Spring) and Nancy Floreen (D-At-Large) spoke about their personal experiences with cancer.

Navarro said she was haunted by the memory of her father, a petroleum engineer in robust health taken quickly by pancreatic cancer. “He looked me in the eye,” Navarro said, and wondered whether his exposure to toxic chemicals had taken a cumulative toll.

Floreen, a breast cancer survivor, said she thought those on both sides were acting in good faith.

But she added: “This is a very personal thing for me, and it’s a personal thing for everyone.”