Biotech companies like Dow Chemical Co. and Monsanto Co. are experimenting with corn, soybeans, tobacco, rice and sugar crops as a cheaper way to mass produce medicines to treat a range of human ailments.

The coalition, which includes Friends of the Earth and Center for Food Safety, accused the USDA of allowing the experimental crops to be planted in open fields without assessing the risk to other crops, wildlife and humans.

The lawsuit was filed in a federal district court in Hawaii, one of the top producing states of pharmaceutical crops.

"The existing regulatory system merely assumes that growing these crops is harmless, even in places where they can contaminate the environment and get into the food supply," said Joseph Mendelson, legal director for Center for Food Safety.

A USDA spokesman would not comment on the lawsuit.

The biotech industry said USDA's regulatory system was effective. "This lawsuit can only serve to impede the potential medical benefits of the technology," said Lisa Dry, spokeswoman of the Biotechnology Industry Organization.

Before field testing pharmaceutical crops, biotech companies must obtain a USDA permit that sets strict planting requirements to minimize environmental risks. This includes planting experimental crops at certain distances away from other crops and cleaning farm equipment.