Heavy metal pollution makes no distinction between how crops are grown. Supposedly clean agricultural practices like organic will offer no protection if the likes of cadmium, arsenic, lead, nickel and mercury are in the soil or water. Human practices like mining and manufacturing are by far the largest source of potential contamination. Such activities release heavy metals into the air and water, from where they find their ways into the soil and plants, from where they are extremely difficult to remove.
Last April, the Chinese government acknowledged that a staggering one-fifth of its arable land is seriously polluted with heavy metals, thanks to decades of aggressive industrial development. China's Environmental Protection Ministry, looking at samples taken between 2006 and 2013, described the situation as "not optimistic." The revelation came after months of speculation about the report, which at one point was not going to be released as the results were considered to be a "State Secret."
Heavy metals can accumulate in the body, causing chronic problems in the skin, intestine, nervous system, kidneys, liver and brain.
The most commonly found heavy metals in the report were cadmium, nickel and arsenic. Cadmium, one of the most toxic of heavy metals, moves through soil layers with ease, and is taken up by a variety of plants, including leafy vegetables, root crops, cereals and grains. Last year it was discovered that nearly half of the rice for sale in the southern China city of Guangzhou was tainted with cadmium.
Nickel and arsenic, the other two pollutants found in greatest amounts, aren't so great either.
In the U.S., arsenic in apple juice has been on the radar since September 2011, when Dr. Mehmet Oz reported high arsenic levels in multiple samples of apple juice that were independently tested for his television show. More than half of the apple juice consumed in the U.S. comes from China.
Oz was taken out to the woodshed by a number of experts and authorities, including the FDA, which disputed the results with its own data. Richard Besser, senior health medical editor for ABC News, called Oz's claims "extremely irresponsible" and compared it to yelling "Fire!" in a crowded theater.
But a few weeks later, the FDA admitted it withheld many test results that supported Oz's claim. Besser apologized to Oz on national television, and soon after the FDA collected about 90 retail samples of apple juice for a new round of analysis. According to FDA documents now available, the levels reported by Oz are consistent with those detected by the agency in samples from China and Turkey.
Last year, the FDA set a limit, also known as an "action level," on arsenic in juice, at 10 parts per billion, the same level that's enforced in drinking water. Currently, the FDA has import alerts set for four companies that deal in apple concentrates, two each in China and Turkey. The products of these companies are regularly tested for arsenic because of previous violations of this action level, but they continue to be imported.
While we don't import a huge amount of food from China, we do consume large amounts of certain things in addition to apple juice, such as garlic and farmed seafood; 80 percent of the tilapia we eat comes from China. Much of China's surface water, including water where aquaculture occurs, is polluted, not only with industrial toxins but also with agricultural fertilizers.
"Foods offered for import into the U.S. are required to meet the same U.S. food safety standards as domestic products," explains FDA press officer Lauren Sucher, via email. "If the FDA encounters information that indicates that a particular product could pose a public health concern, the FDA can target that product for increased testing."
When asked if the revelation that 20 percent of China's farmland is polluted with heavy metals will inspire increased testing on Chinese imports, Sucher replied, "The FDA doesn't announce its actions in advance. If our surveillance sampling indicated a problem with a particular commodity, the agency would take steps to protect the public."
Wary consumers who aren't interested in waiting for the FDA to possibly ramp up its testing of Chinese food imports can take their own measures to minimize the possibility of contamination. Local, as in American-grown produce, will trump labels such as "organic" if the food in question was grown in a potentially polluted place.
In fact, if the food is grown in a polluted place, organic produce could contain more heavy metals than conventionally grown food. Organic agriculture practices include the use of manure, which could add heavy metals to the soil if the cattle were eating contaminated feed, according to Michael Schmitt, a soil scientist at the University of Minnesota. "Once you put metals in a field," he told me by phone, "they don't go away."
The notion that organic food from a polluted place like China could carry more heavy metals than nonorganic food from the U.S. puts a new spin on the idea of eating locally. In this case, eating locally could mean consuming food grown anywhere in this vast continent. But in a way, the reasons are similar to why many people prefer buying from the local farm stand: You have more information about how something is grown. But using this information requires knowing something about where you live. Such as, is there any heavy metal contamination around here?