It's not always easy being green.

Reusable shopping bags reduce plastic and paper waste, but a number of bags available at major retailers and supermarkets are tainted with lead, according to an investigation by the Tampa Tribune.

The lead, contained in the paint on the outside of the bags, isn't likely to rub off on your tomatoes and bananas. But the levels of the toxic metal are high enough that the bags would be considered hazardous waste by the county health department featured in the Tribune's report. The highest lead levels were in the bags tested from grocery stores Publix and Winn-Dixie. The Target bag tested by the Tribune had, by contrast, "almost undetectable levels of lead," the newspaper reported..

Sen. Chuck Schumer, D-N.Y., has called for a federal investigation into the safety of the grocery bags, many of which are made in China.

Click here for Tampa Tribune reporter Richard Mullins' suggestions for what shoppers should do: