Industry experts say there are a lot of chemicals that could contaminate Hawaii’s medical marijuana.

Dispensaries are set to open in Hawaii in July, and state lawmakers are pushing a broad bill to address many of the obstacles the industry is facing. One is how to regulate marijuana testing.

The proposed Hawaii law would set requirements for testing medical marijuana’s potency and would also test for contaminants such as heavy metals, bacteria and pesticides, which industry experts say is necessary to ensure patient safety. Under state rules, dispensaries must send all marijuana products to a certified laboratory for testing.

Other states have had problems establishing rules on testing. That includes dealing with recalls because of contamination and facing marijuana shortages when crops were lost to pests.

“You have states stumbling around trying to figure this out,” said Chris Walsh, managing editor of the Marijuana Business Daily. “They’ve implemented testing regulations, but in many cases they don’t really know what they’re doing.”

The proposed Hawaii law would require testing for potency of chemicals that naturally occur in marijuana, such as THC, the main ingredient that can cause psychological effects. It would also set limits and test for pesticides that are currently regulated by the U.S. Environmental Protection Agency, as well as solvents that are used to make products like oils and tinctures.

Most industry advocates were supportive of the Hawaii bill but wanted to change some of the proposed rules to increase safety and keep costs down for patients.

Christopher Garth, executive director of the Hawaii Dispensary Alliance, said testing for heavy metals could be unnecessary. Meanwhile he wanted stricter rules for allowable pesticide levels than currently required in the bill, but said the state should narrow the list of pesticides to ones that are likely to be used on marijuana.

Because marijuana has been federally illegal for so long, it can be difficult to make rules about testing because there’s little research on it, Garth said. For instance, marijuana can be smoked, eaten or applied on the skin, so it can be difficult to establish policies on pesticide levels without data, he said.

The Hawaii Department of Health can award dispensary licenses in April.