Is it safe to cook cans of food in the pressure cooker?

Dear EarthTalk: I’ve often cooked canned foods in their own can, things like condensed milk and mushroom soup. I put the can without opening it in the pressure cooker, cover it with water and let it cook for 30 minutes. The results are amazing. Is it safe to do that? Can metals leach into my food?

Mercedes Kupres

via e-mail

For starters, can makers don’t recommend using their products for anything but storing food unopened until it’s ready to eat.

“Cans are reliable, recyclable, durable packages that keep beverages and foods fresh and allow them to be transported safely for thousands of miles, even into remote regions — but they were not made to be used as cooking containers,� says Scott McCarty of Colorado-based Ball Corp., a leading U.S. food and beverage packaging maker.

Proponents of can-cooking cite the fact that many canned goods are already heated up in their cans to kill bacteria during the canning process, so what harm could a little more heating do? McCarty concedes that some cans are indeed heated during the packing process. “But that isn’t all cans or all foods, and it is a carefully controlled and monitored process done in an environment that is made to do it.�

As for what metals may be leaching into your canned food, it depends. In the United States, most food cans are made of steel, while beverage cans are usually made out of aluminum. Chromium and nickel can find their way out of steel, but the amounts would be miniscule to nil. Slightly more troubling is the fact that aluminum — large amounts of which have been linked to nervous system disorders and other health problems — could in theory leach out of cans into their food or drink contents.

In order to prevent any such leaching — which is bad for the food and eater but also for the can (as it can cause corrosion) — the insides of most cans on grocery shelves today are coated with food-grade epoxy. But these liners have been shown to contain Bisphenol-A (BPA) and other potentially harmful chemicals. BPA is a synthetic plastic hardener that has been linked to human reproductive problems and an increased risk of cancer and diabetes. A 2009 analysis of common canned foods by the nonprofit Consumers Union found measurable levels of BPA in a wide range of items including some bearing a “BPA Free� label.

The U.S. Food and Drug Administration is currently reviewing whether or not to allow BPA to come into contact with food items at all. In the meantime, some forward-thinking companies aren’t waiting around for an FDA ruling. Eden Foods, which prides itself on the wholesomeness of its products, worked with its packaging manufacturer, Ball Corp., back in 1999 to switch out traditional epoxy-based liners with a baked-on, BPA-free enamel lining derived from plant oils and resins.

This technology is nothing new; in fact, Eden stumbled upon it by asking Ball what it used before epoxy liners became standard some three decades earlier. While the custom-made cans cost 14 percent more than industry-standard cans would, Eden maintains it’s worth the extra expense (which amounts to some $300,000 extra per year). “It was the right thing to do,� says Michael Potter, Eden’s president. “I didn’t want BPA in food I was serving to my kids, my grandkids or my customers.�

Dear EarthTalk: Oceans are in big trouble and I understand President Barack Obama is creating a high-level ocean council to address them. What are the major issues?

Steve Sullivan

Bothell, Wash.

Our oceans are indeed in a terrible state, thanks primarily to unrestrained commercial and industrial activity. Overfishing and pollution have decimated once abundant stocks of fish and other marine life, and the damaging practices continue to this day despite international agreements outlawing them.

Our appetite for seafood has pushed three-quarters of the world’s fisheries to or beyond the limits of sustainability, while nine out of 10 of the sea’s large fish like tuna and swordfish have disappeared. And while it is still unclear what toll global warming will have on oceans — coral reefs dying and powerful ocean currents shifting or shutting down are two scary scenarios — the outlook is grim at best.

While George W. Bush was no friend to the environment overall, his record on ocean protection is actually not too bad. After convening a commission of experts from various disciplines to report on the state of U.S. oceans, his administration took steps to protect 215 million acres of biologically rich deep sea ocean habitat in the Pacific near Hawaii and Guam. The newly protected areas are off limits to resource extraction and commercial fishing but open for shipping traffic, scientific research and minimal impact recreation — and should provide a boon for fish and other marine species trying to recover from decades of abuse. But while such protections are a huge step in the right direction, they represent less than a drop in the bucket as to what still needs to be done to help fish stocks and marine ecosystems recover.

In light of ongoing threats, President Obama last June set up a task force to craft a national ocean stewardship policy. Led by Nancy Sutley, chair of the White House’s Council on Environmental Quality, the task force is currently working to draft a framework for sustainable management of American coastal and ocean resources.

Currently 20 different federal agencies oversee some 140 ocean protection laws; Obama has charged his task force with pulling together all the different authorities and laws to focus attention on addressing the most serious challenges facing the oceans and those who manage them.

Environmentalists have been quick to praise Obama for creating the task force — something called for by Bush’s oceans commission and other experts — but it is unclear how effective it can be given competing political priorities. Some members of Congress are pushing an omnibus ocean protection bill called Oceans-21, which aims to regulate fisheries, establish a network of protected areas, provide an oceans management framework to rescue coasts and off-shore areas, and help ocean life survive global warming.

Fortunately, Americans are not the only ones concerned about the world’s oceans. The United Nations launched its Oceans and Coastal Areas Network — later renamed UN Oceans — in 2003 to coordinate ocean and coastal efforts around the world. More recently, several island nations in the western Pacific and Indian oceans formed the Coral Triangle Initiative, adopting a 10-year plan of action to avert growing threats to coral reefs, fish, coastal mangrove buffers and other marine resources across the region. While the challenges may be greater than ever, at least now our oceans are getting some long-overdue attention; only time will tell if we took action in time to stave off a global collapse of marine ecosystems.