All it does is create foam, but the downside is the residue has been found in the brains, livers and hearts of cancer patients when they were autopsied.

Banned in today's cosmetics, the cancer-causing tar residue can be found in burnt substances and foods such barbecue, coffee, cigarette smoke, and coal tar.

And what about that innocent-looking arugula: Will pesticide residue cause cancer, or do the leaves themselves harbor E. coli?