Why can’t I put certain kinds of plastic—such as toys or Styrofoam cups—in the blue box?

There are 50 families of plastic on the planet, and all of them can theoretically be melted down and remoulded. But some plastic products are harder for Toronto’s waste management people to sell off to recycling companies—the people who grind our discarded items into chips, wash them down and sell them to manufacturers of everything from synthetic lumber to high-tech polar fleece. Plastic motor oil bottles contain residual gunk that’s hard (and uneconomical) to remove. Toys, such as deceased GI Joes, are equally tricky, because they often have metal parts, and because the plastics used in them vary widely in type and quality. Styrofoam, meanwhile, is cheap to make from scratch but expensive to transport (because of its lousy space-to-weight ratio) and to reconstitute.

The current doyenne of recycled plastics is high-density polyethylene, of the kind found in detergent bottles. HDPE is easily converted into plastic piping and sells for a tidy $600 per tonne. Toronto recycles approximately 6,000 tonnes of plastic annually, which works out to roughly 300 fewer trucks a year bound for Michigan landfills.