SHIRLEY -- Recycling is a good thing. Good for the environment, anyway, removing tons of recyclable and in some cases nonbiodegradable materials from landfills.

But for the town, which implemented a pay-per-bag program for weekly trash pickup several years ago that includes curbside recycling pickup every other week as part of the package, there's a point when it can be too much of a good thing, according to the Board of Health. The board discussed a case in point at its monthly meeting Monday night.

Take the numerous 35-gallon barrels parked in front of Lucille Lindley's residence on Longley Road every recycling day, for example. So many and on such a consistent basis that health board members took notice and asked Lindley to come in and explain.

At issue would be whether the residence might house an unregistered home business or if the homeowners might be trucking in recycling from an off-site business or some other source, such as a resident or residents in another town that doesn't offer free recycling.

None of the above, according to Lindley, who attended the recent health board meeting with her house mate, a man she called John who declined to sign the meeting register.

"We asked you to come in to talk about the large amount of recyclables you put out," Chairman Joseph Howlett said. He sketched how the pay-per-bag system works and explained why the board is concerned.

Lindley said the recycling she puts out is mostly other people's litter. "We pick it up from the roadside," she said. Asked where, she said it came from "all over town."

Citing "heavy traffic" on Longley Road in particular, including a lot of trucks, Lindley said her property has "a lot of frontage." If she and her companion didn't pick up the stuff folks fling from passing cars or drop by the roadside, such as plastic water bottles, small "nips" from the package store and other items, "it would stay there" until the annual spring cleanup day, she said.

Howlett conceded that there's no roadside cleanup crew in Shirley.

But member Donald Farrar was skeptical of the notion that discarded roadside recyclables could account for all those barrels, up to 15 at a time, in some instances.

He also debunked a misconception that Lindley, John and a couple that came to support her had apparently come in with that recycling generates revenue for the town.

The opposite is true, Farrar said. Instead of being paid for paper and cardboard, for example, which once brought in about $20 a ton, a diminished New England market has shifted the paradigm. Now, communities pay for recycling, one way or another.

Here, the trash hauler the town contracts with rolls it in with trash pickup, and the incentive works. People are recycling more and throwing away less. That's good for the planet, but there's a financial downside for the town.

At some point, the balance tips. If the town doesn't make enough money from the pay-as-you-throw system to cover the cost of roadside trash pickup and recycling, "we might have to get out of the business," Farrar said.

Or ask Town Meeting to offset the cost, member Jackie Esielionis said.

Ironically, the town is receiving an award for the percentage of recycling it has achieved since the pay-per-bag system was implemented.

In any case, board members agreed that in the future, they might limit the number of containers each household puts out on recycling day, say two 35-gallon trash bins. In the meantime, they'll continue monitoring the roadside output at 44 Longley Road.