The comments follow the publication of a study last month in the journal Environmental Science and Technology, which reveals that rice bran contains the highest inorganic arsenic content of all widely available commercial rice products.
However, in response to an inquiry from NutraIngredients-USA.com, NutraCea took issue with the methodologies employed for the study, and re-iterated its position that “there is no credible scientific evidence linking consumption of rice products with cancer or any health risk”.
Study findings
Rice bran, which is originally a by-product of rice processing that is usually discarded or used for animal feed, has emerged in recent years as a functional ingredient for use in foods and dietary supplements. It is considered to be a rich source of vitamins, minerals, antioxidants and fiber.
However, the latest study published by Andrew Meharg from the University of Aberdeen, UK, and colleagues, found that rice bran and rice bran solubles contain inorganic arsenic levels of around 1mg/kg dry weight, which is around 10-20 times the concentration found in bulk grain.
The researchers tested rice bran samples from a number of suppliers, including NutraCea.
For full details on the study, see the NutraIngredients-USA.com article published here.
Tolerable intakes
The study stressed that the US and EU currently have no standards for arsenic levels in food, but the US has a 0.01mg/liter limit in drinking water. The World Health Organization (WHO) has also placed a provisional level of 0.01mg/l in drinking water. The UK has standards that date back to 1959, and that set the limit of 1mg/kg total arsenic in foodstuffs.
However, NutraCea told NutraIngredients-USA.com that the study authors do not explain the significance of the provisional tolerable weekly intake (PTWI) for dietary inorganic arsenic set by the FAO/WHO Joint Expert Committee on Food Additives.
The PTWI is defined as the amount of a contaminant that can be ingested from food and water on a continual basis over a lifetime without appreciable health risk.
The PTWI for arsenic is 0.015 mg per kg of body weight per week.
For a more detailed breakdown from WHO, click here.
Water vs food contamination
NutraCea also said the authors “made a critical error in using water standards for non consumption rather than dietary intake standards”.
“WHO drinking water standards for arsenic are applicable to water treatment facilities and reflect what is attainable in purification of water. The PTWI reflects the amount of arsenic that can be regularly consumed via both water and food over a lifetime without appreciable health risk,” said the firm.
However, Professor Meharg explained that he and his colleagues had used risk calculated from dose on a body weight basis to compare water verses food sources because “it is the risk that is important in considering the implications of a toxicant in a diet”.
“Once the arsenic crosses the gut membrane the human body does not distinguish if the arsenic comes from water or food. The fact that food standard setting has lagged far behind water standard setting dose not mean that food risks are not just as important as water risks,” he told NutraIngredients-USA.com.
Less arsenic
Professor Meharg stressed that his study was not targeting one company or its products.
“What I’m concerned about is the product in general. We’ve raised problems in the past with rice grain, baby rice and rice milk. Rice bran is just another product that needs to be seriously thought about.”
He added that “it is not the use of rice per se that is of concern, it is the use of rice or rice products with high levels of arsenic that is problematic. Many regions of the world use rice with low levels of arsenic in them. (…) All novel products coming onto the food market should be tested for safety.”
NutraCea said that its rice products are tested regularly for heavy metal content and have “consistently” met the requirements of its customers.
“Our products comply with the regulatory requirements in countries all over the world. We fully intend to continue to provide safe and nutritious rice products to all of our valued customers.”