I felt kind of sheepish upon arriving at the seminar "Are Chemicals Making Us Fat" at the 2011 Environmental Action Conference Saturday at Bentley University, because the subject was obesogens, and I didn't know what obesogens are.

So you can imagine how I felt, near the end of the session, when they showed this video, in which a bunch of South Shore fourth- to sixth-graders make clear they knew, while making clear, for the rest of us, what obesogens are: "ingredients that enter our bodies and interfere with our endocrine systems, specifically our metabolic functions."

Heretofore, while carrying the message that obesity's causes are extremely complicated, I'd not included things like BPA, the compound used in polycarbonates and other things. Yes, I'd heard that BPA was to be avoided  — we've done so in our son's things, tossing away hand-me-down bottles and such that had it — but the "why" had just rushed by me in the unstoppable information torrent.

Now, thanks to presenters Cindi Luppi and Kristi and Kyle Marsh, I'm a bit more caught up. Such as: BPA also shows up in the coating on fast-food wrappers, in the powder sometimes noticeable on thermal printing paper (think register receipts), and in cans' epoxy lining (veggies, soda, infant formula). The substance has been shown to leach out into foods, particularly when it's heated.

Luppi included phthalates, which she said have been especially linked with eating disorders in males, and perfluorochemicals (PFCs), which are used to to make teflon and gore-tex, among other products, in her presentation. She has worked with the group Clean Water Action since 1994.

Kristi Marsh is a breast-cancer survivor motivated by her disease and recovery to re-examine all the substances in her family's lives. Her friends kept asking about what she was learning, and so she founded Choose Wiser, through which she shares her knowledge.

Kyle Marsh is 10 and is the first actor to appear in the video. His other contribution to the seminar was to offer 10 steps people can take toward chemical health. Among them: Choose fresh or frozen veggies to avoid the cans' lining, cook with cast iron or other non-teflon products, and choose organic food or better: "I like my beef for tacos grass-fed," he said in full foodie-activist voice. 

What I liked about Kristi Marsh's presentation is that she's not the firebrand: "I don't know if obesogens exist," she began. And, later: These substances were "designed for a purpose. They weren’t put in to hurt us, trap us, or trick us. They were trying to do good. But now we want to make better choices," she said, sidestepping the ideologically tinged judgment of whether they exist.

She's just trying to do her best for her family, she said. "I can't imagine doing anything more important." 

Meanwhile, to return to the seminar's provocative title: Are chemicals making us fat? That's an overstatement, almost certainly. But as Kristi Marsh said, the possibility is probably enough for us to begin making different choices.