Grassley's legislation is named for 18-year old David Rozga of Indianola, Iowa. Rozga's parents say he took his own life after smoking K2 purchased at a suburban shopping mall.
"They don't care who they hurt or what they do," said Rozga's father Mike in urging Congress to ban the chemicals.
The retail stores trade group says a ban would send the trade "underground" and is unnecessary since most stores will not sell to anyone under the age of 18.
"Teenagers don't belong touching this stuff," said the group's executive director Dan Francis.
Yet, as part of the "20/20" investigative report, a 14-year-old and a 16-year-old wearing undercover cameras in New York and Los Angeles were easily able to buy K2 and Spice at retail stores.
The clerk of one store along Venice Beach in Los Angeles admitted he had not asked for any valid ID and conceded it was wrong for him to sell to a 16-year-old boy.
Asked about the possible consequences, the clerk told ABC News, "nothing good."