Arsenic is a tasteless and odorless heavy metal that can occur naturally in soils. While small levels of organic arsenic are not considered dangerous, the U.S. Department of Health and Human Services says exposure to the metal has caused a number of known health problems, including neurodegenerative conditions and cancer.
For decades, arsenic-containing pesticides and defoliants were used in the cotton fields of the south-central United States. Although this type of treatment is no longer in practice, the toxic metal has accumulated in the soil. Now much of this land is used for rice crops, and rice grown in this area may contain elevated levels of arsenic.