Dhaka, March 13 -- But new trade data for January, the first month that the agreement took effect, shows that US exports of plastic scrap to poorer countries have barely changed, and overall scrap plastics exports rose, which environmental watchdog groups say is evidence that exporters are ignoring the new rules.

The US companies seem to be relying on a remarkable interpretation of the new rules: Even though it's now illegal for most countries to accept all but the purest forms of plastic scrap from the United States, there's nothing that prevents the United States from sending the waste. The main reason: The United States is one of the few countries in the world that didn't ratify the global ban.

"This is our first hard evidence that n...