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Heavy metal pollution makes no distinction between how crops are grown. Irrespective of whether farming practices are organic or conventional practices are used, if the likes of cadmium, arsenic, lead, nickel and mercury are in the soil, water or air they can contaminate food and poison the people who consume it. With enough exposure, heavy metals can build up in the body, causing chronic problems in the skin, intestine, nervous system, kidneys, liver, and brain. Some heavy metals occur naturally in soil, but rarely at toxic levels, while human activities like mining, manufacturing and the use of synthetic materials like paint, and even some agricultural chemicals, can release heavy metals into the air and water, and from there they find their way to the soil. And once in the soil, heavy metals are virtually impossible to remove.

China acknowledged last April 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 looked at data sampled between 2006 and 2013 and described the situation as “not optimistic.” The most commonly found heavy metals were cadmium, nickel and arsenic. 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.”

Cadmium, one of the metals found in high concentrations in Chinese soil, is one of the most toxic heavy metal pollutants. It 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, which caused a major uproar.

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 popular radar since September 2011, when 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.