SAN FRANCISCO  These days, every skin lotion and dish detergent on store shelves gloats about how green it is. How do shoppers know which are good for them and good for the earth?

It was a similar question that hit Dara O’Rourke, a professor of environmental and labor policy at the University of California, Berkeley, one morning when he was applying sunscreen to his young daughter’s face.

He realized he did not know what was in the lotion. He went to his office and quickly discovered that it contained a carcinogen activated by sunlight. It also contained an endocrine disruptor and two skin irritants. He also discovered that her soap included a kind of dioxane, a carcinogen, and then found that one of her brand-name toys was made with lead.

And in looking for the answer, he hatched the idea for a company that used his esoteric research on supply chain management. “All I do is study this, and I know nothing about the products I’m bringing into our house and putting in, on and around our family,” Mr. O’Rourke said. But when he wanted to find that information, he could. Most consumers would struggle to do so.