When it comes to making toys greener, Walmart isn't playing around

This is the third in a series of stories about Walmart's supplier sustainability index. An overview is here, and a story about flour, bread and agriculture is here. Today's topic: plastic toys.

Walmart wants to improve the sustainability of plastic toys. The giant retailer isn't playing around.

Specifically, the company wants to improve the safety of workers who make the toys. It also wants to make sure that manufacturers are taking steps to use fewer so-called "chemicals of concern" in toys. It would like suppliers to deal with any issues raised when kids outgrow Barbie or GI Joe and throw them away. If paper or wood goes into toy packaging, Walmart wants to know whether it is "sourced in accordance with a credible certification system that addresses ecosystem impacts and biodiversity."

Some critics think Walmart is taking this too far. That's what this story is about.

Walmart's supplier sustainability index, which is being rolled out to thousands of suppliers, is the biggest environmental initiative in the company's history. It likely will do enormous good, requiring companies that make consumer products to examine their environmental impacts in ways they never have done before. But the index also raises questions about how the world's largest retailer (2012 revenues: $469 billion) is exercising its market power.

Consider, as an example, PVC, or polyvinyl chloride plastic, commonly known as vinyl. It's a widely used plastic that shows up in toys, including such iconic plastic toys as Hasbro's My Little Pony and Mattel's Barbie. It can be made soft or rigid. It is rugged, moldable, low-cost and excellent at holding color.

What, if anything, is wrong with PVCs? That depends on who you ask.

Greenpeace has campaigned for a decade against PVCs. It says: "This commonplace plastic is one of the most toxic substances saturating our planet and its inhabitants. PVC contaminates humans and the environment throughout its lifecycle: during its production, use, and disposal."

Next page: The vinyl debate