Two U.S. senators introduced legislation Tuesday requiring federal agencies to come up with solutions to the waste caused by oversized eye drops and single-use drug vials, citing a ProPublica investigation published last month.

The bipartisan effort by Sens. Amy Klobuchar, D-Minn., and Chuck Grassley, R-Iowa, is calling for both the Food and Drug Administration and the Centers for Medicare and Medicaid Services to come up with a plan to reduce the waste, which is estimated to cost billions of dollars a year.

“With the skyrocketing costs of prescription drugs, American taxpayers shouldn’t be footing the bill for medicine going to waste,” Klobuchar said in a press release announcing the bill, known as the Reducing Drug Waste Act of 2017.¬†Sens. Dick Durbin, D-Ill., and Jeanne Shaheen, D-N.H., are also co-sponsoring the legislation.

“It’s no secret that wasteful health care spending is a significant contributor to the rising cost of health care in the United States,” Grassley said in the release.

Drug companies often require patients to pay for expensive liquid medications, such as eye drops and cancer drugs, which are produced or packaged in ways that lead to waste. Drug companies have known for decades that eye drops are larger than what the eye can hold, sometimes two- or three-times too big. As a result, the excess medication overflows the eye and runs down users’ cheeks or is ingested through their eye ducts. This waste can cause many patients to run out of medicine before their health insurance providers allow them to refill their prescriptions.

Some of the largest producers of eye drops, from expensive vials for eye conditions like glaucoma to over-the-counter drops for dry eyes, have conducted research studies showing that smaller drops work just as effectively yet they have continued to produce the larger sized drops. Novartis, owner of Alcon, one of the leading eye care companies, said the larger drop size allowed a margin of safety to help patients administer the drops. Other eye drop makers declined to comment.

The way some cancer drugs are packaged often results in a significant amount of the drug being tossed in the trash. The drug company Genentech, for example, switched this year from shareable vials of its cancer drug Herceptin to single-use vials, causing excessive waste. One California cancer center estimated the change would lead to an average of $1,000 in wasted medicine per patient, per infusion. Patients are billed for such waste.

A recent research study led by Dr. Peter Bach, director of the Center for Health Policy and Outcomes at Memorial Sloan Kettering Cancer Center in New York, found that single-use cancer vials wasted nearly $3 billion annually in cost increases and medicine that must be thrown away.

“From cancer drugs to expensive eye-drops, many drug companies insist on selling their products in excessively large, one-size-fits-all vials that contain more medicine than the average patient needs,” said Durbin, one of the lawmakers sponsoring the bill. “This is a colossal and completely preventable waste of taxpayer dollars, and it means American patients and hard-working families are paying for medication that gets tossed in the trash.”

Bach’s study proposed making drug companies produce vials in additional sizes, so they could be delivered in a way that’s more efficient, or requiring drug companies to give rebates on unused medicine. He said it’s too early to know what the federal government’s solution would be, but the new bill is a positive step forward.

“This could be legislation that saves Medicare and sick patients a lot of money,” Bach says.

Dr. Alan Robin, a Baltimore ophthalmologist, has been urging drug companies to reduce the size of their eye drops for decades. When he heard Monday about the senators’ proposed legislation, he started to cry.

“I’m literally crying with joy,” Robin said. “I’m very concerned about both the cost issues associated with waste, the side effects on patients, and also the environmental impact of waste.”