Arsenic is a toxic element commonly found in food such as rice, marine animals, or algae. The toxicity of arsenic depends heavily on the chemical species. Inorganic arsenic compounds, for example, are more toxic than some of the organic arsenic species found in food.

Ann Ruttens, Veterinary and Agrochemical Research Centre (CODA-CERVA), Tervuren, Belgium, and colleagues have studied the concentrations of different arsenic species in food before and after food preparation. The team analyzed rice, vegetables such as carrots and leeks, different fish, scampi, mussels, and different algae, among other foodstuffs. The samples were treated by boiling in water, steaming, frying, microwaving, or soaking in water (for algae). Rice was prepared both with excess water, which is discarded after cooking, and by cooking it until dry. The foodstuffs were analyzed before and after preparation using high-performance liquid chromatography coupled with inductively coupled plasma mass spectrometry (HPLC-ICP-MS).

The team found that arsenic was released from the food to the broth during boiling, steaming, frying, or soaking. Total arsenic concentrations were reduced by up to 57 %, but only if the broth was removed after cooking. High temperatures enhance the release of As from food, hence, cooking rice and discarding the broth is more efficient than washing it. The different arsenic species were released at different rates, with inorganic arsenic released at the highest rates, followed by small organic species such as dimethylarsinate (DMA). According to the researchers, consumers can reduce their arsenic intake by boiling food in an excess of water, but this has to balanced with the loss of vitamins and other nutrients in the process.

• Arsenic Release from Foodstuffs upon Food Preparation,
  Karlien Cheyns, Nadia Waegeneers, Tom Van de Wiele, Ann Ruttens,
  J. Agric. Food Chem. 2017.
  DOI: 10.1021/acs.jafc.6b05721