When documentary filmmaker Andrew Nisker’s father, Harold, an avid golfer who was always the picture of health, fell ill with non-Hodgkin lymphoma, he was heartbroken and perplexed and then alarmed at what he learned. Exposure to pesticides is a marker of the disease and the only place his father could have been exposed was at the golf course, he reveals in his newest film.

In an effort to promote awareness about the dangers of toxic pesticides on golf courses and athletic fields Friends of Animals, an international nonprofit wildlife advocacy and animal protection organization headquartered in Darien, is sponsoring a free screening of the film followed by a discussion with Nisker. The screening, which is open to the public, will be held at the Darien Library on Tuesday, Oct. 1 at 6:30 p.m. The event is cosponsored by the Darien Garden Club, Norwalk River Watershed Association, Darien Nature Center, Darien Pollinator Pathway, Beyond Pesticides, Norwalk Land Trust, Rowayton Gardeners and the Rowayton Gardeners’ Pollinator Pathway.

The 78-minute film, “GroundWar: When Playing Fields become Battlefields,” takes viewers on Nisker’s journey as he talks with health experts, golf industry representatives, environmental advocates and family members of cancer victims exposed to toxic pesticides.

Friends of Animals President Priscilla Feral said the documentary calls vital attention to a pressing issue facing local communities. As a member of the Rowayton Gardeners Club, Feral has worked with district commissioners in Norwalk to switch to organic, pesticide-free alternatives in Pinkney Park, which is situated along Five Mile River and provides habitat for aquatic organisms, fish, songbirds, amphibians and small mammals. It also hosts many community events, such as Shakespeare on the Sound where families picnic. The club continues to work with public officials to address other areas.

“We are sponsoring the event to provide information on non-toxic alternatives,’’ she said. “It’s important that individual municipalities are able to address the issue of the dangers of pesticides in sensitive ecosystems within their borders, from areas where children and pets play to public gardens.”

Nisker said he hopes the screening can bring light to a subject often not discussed.

“My father would be walking through these fields of greens, be he had no idea how those fields were kept and what was being sprayed,’’ said Nisker. “I don’t think many people think about that when they are looking at beautiful green park or landscapes. I used to think, ‘well, that’s the way it should look,’ but now that’s totally turned on its head.”

Anyone interested in attending can register for the event at Groundwar.Eventbrite.com.

This event is held at, but not sponsored by, Darien Library. Any views and opinions expressed are not those of the library.

Friends of Animals, an international animal protection organization founded in N.Y. in 1957 and headquartered in Darien, advocates for the rights of free-living and domestic animals.