What’s going to happen to the 4.3 million Galaxy Note 7 smartphones that Samsung Electronics Co. has recalled over exploding batteries? No one is really sure, and Greenpeace on Monday urged the company not to merely dump the phones, warning of “environmental disaster.”

Samsung KR, -1.00% has not publicly stated how it will dispose of the phones, other than to say they would not be repaired or reused. “We have a process in place to safely dispose of the phones,” the company told Vice Media’s Motherboard recently. Samsung did not immediately respond for comment Monday.

Greenpeace called on Samsung to find new ways to recycle the massive amount of metals and rare earth elements inside the phones, and to be transparent with its disposal methods.

About 50 elements go into a Note 7, but only 12 can be recycled, due to today’s inefficient recycling methods.

According to German researchers at the Oeko-Institut, the 4.3 million Note 7s that were produced contain more than 20 metric tons of cobalt, more than 1 ton of tungsten, 1 ton of silver, 100 kilograms of gold and between 20 and 60 kilograms of palladium, Greenpeace said.

“These materials could be recovered but will instead end up harming the environment if Samsung doesn’t repurpose or reuse them,” the environmental group said in a statement.

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While most of the metals themselves are not necessarily toxic, the methods of extraction can be, with mercury and cyanide used for some mining operations. The mining techniques to acquire those metals can also be environmentally destructive and are highly inefficient, according to a 2013 report by the Institute of Electrical and Electronics Engineers, which estimated that it takes about 165 pounds of raw materials to build a single smartphone. To simply destroy all the smartphones would be a massive waste of costly resources.

“Samsung now has an opportunity to set an example for the industry — will it recover and reuse the precious metals and other valuable materials in these 4.3 million devices and avoid an environmental disaster or will it simply dump them?” Jude Lee, senior IT campaigner at Greenpeace East Asia, said in a statement. “We are launching a global petition challenging Samsung not to dump the phones and instead take this chance to totally rethink how it designs and produces its products.”

One major problem for potential recycling efforts is the Note 7’s battery, which is glued to the device. Wired has reported that recyclers must carefully pry out the potentially explosive battery from each device, which one engineer compared to “brain surgery with a patient that might catch fire.”

Making the battery removable in the first place would have streamlined the recycling process considerably, and likely made a recall of the entire device unnecessary — vastly improving the phone’s sustainability.

“All electronics and smartphone manufacturers should learn from this incident and design products that can be more easily repaired, recycled or reused,” said Elizabeth Jardim, senior corporate campaigner for Greenpeace USA, in a statement.