Unsure where it's coming from, it's nearly impossible to regulate.Luigi Amasia Photos/Flickr
Fifty years ago, Rachel Carson revealed in Silent Spring how toxic chemicals, like DDT, work their way from soil and plants into animal and human bodies. Her book was a call to action against the continued, unchecked addition of poisons to the environment.
Last week, Consumer Reports published findings of "worrisome" levels of arsenic in ordinary rice sold in the U.S. Arsenic contamination affected a variety of rice forms: brown and white, organic and regular, long and short-grain. The researchers found arsenic in dozens of commercial products including baby food, cereals, rice cakes and rice drinks. The FDA reported similar results in an initial statement released last week and is pursuing further studies of the matter.
Arsenic is a common, naturally-occurring element. The metalloid substance, famous for its tasteless, odorless and occasionally lethal properties, sits at number 33 in the periodic table. Arsenic arises in both organic and inorganic forms. One source of organic, dietary arsenic is seafood, particularly shellfish. Most studies of arsenic's toxicity have focused on its inorganic forms, including lead-arsenate, used in U.S. pesticides until the 1980s, and other chemical preparations still used in fertilizers, wood treatment and for other purposes today.
"The results came as no surprise," said Keeve Nachman, a researcher at the Johns Hopkins Center for a Livable Future. Arsenic is ubiquitous, he said, and it, derives from both natural and man-made processes. Because rice is grown in watery fields, it's prone to absorbing chemicals from groundwater. "The new analysis is important because it was the first to look closely at arsenic in a 'market basket' sample," he said.
Consumer Reports found that brown rice consistently had higher levels of arsenic than white rice of the same brand. This pattern might be explained by the polishing process in white rice manufacturing, which removes the outer grain layers. The bran removed in the milling process contained high arsenic levels, according to the report.
They also determined that white rice produced in the south-central U.S. -- in Arkansas, Louisiana, Missouri and Texas -- has higher levels of arsenic than similar products from California, Thailand and India. Some investigators have suggested that arsenic in rice from the cotton belt region is attributable to past use of arsenic-containing pesticides to control boll weevils.
The analysis provides a detailed table on total arsenic, in parts per billion, and inorganic arsenic, translated to micrograms per serving, for dozens of brand-name rice products ranging from Kellogg's Rice Krispies (relatively low, 2.3 - 2.6 micrograms arsenic/serving) to Trader Joe's Organic Brown Pasta Fusilli (relatively high, 5.9 - 6.9 micrograms arsenic/serving). The organization offers dietary recommendations for children and adults who might want to limit potential exposure to arsenic from rice.
"The take home point for consumers is to be concerned," says Michael Hansen, a senior scientist at Consumer Reports. "People should be aware of the levels they're eating and try to moderate their intake."
Apart from measuring arsenic in rice, the Consumer Reports group used a federal database, the National Health and Nutritional Examination Survey (NHANES), to establish that eating rice was associated with a significantly higher level of arsenic in urine. The NHANES work was carried out apart from the Consumer Reports research, so it's unlikely that participants' responses were influenced by concern about arsenic. Those who reported having eaten rice, and not shellfish (another potential source of dietary arsenic), on the day before the study had a 44 percent elevation in urine arsenic, overall, as compared to those who hadn't ingested either. Mexicans, other Hispanics, and Asians were most affected.