Scientists have found half of rice varieties they tested exceeded maximum arsenic limits for young children in the United Kingdom.

A team at the University of Sheffield’s Institute for Sustainable Food found 28 of 55 rice samples sold in the U.K. contained levels of arsenic that exceeded European Commission regulations for rice for infants or children under the age of five.

The U.K. follows European Commission regulations so that inorganic arsenic concentrations must be below 0.20 milligram per kilogram in white (polished) rice and less than 0.25 mg per kg in brown (unpolished) rice. However, the concentration in rice used for infant food production or direct consumption is set at a maximum of 0.1 mg per kg.

Potential risk for infants
Results showed brown rice had higher levels of inorganic arsenic than white or wild rice because it contains the bran – the outer layer of the grain. Organically grown rice contained significantly higher levels than non-organically grown rice. White rice was found to have the lowest levels of arsenic.

Researchers concluded that babies under the age of one must be restricted to a maximum of 20 grams per day of the 28 rice varieties that breached regulations to avoid risks of developing cancer in later life. Suppliers were anonymized so it is not clear which brands were involved.

Previous studies have found up to 90 percent of households in the U.K. buy rice with the average person consuming about 100 grams per week.

The study, published in the journal Ecotoxicology and Environmental Safety, showed health risks due to rice arsenic consumption are confined mainly to infants in the U.K. Rice and rice-based products are used for weaning and as baby food, because of nutritional benefits and relatively low allergic potential.

Some adverse effects reported to be associated with long term ingestion of inorganic arsenic are skin lesions, cancer, developmental toxicity, neurotoxicity, cardiovascular diseases, and diabetes.

“Brown and wild rice are healthy foods full of fiber and vitamins, and there is no need for grown-ups to avoid them – but it is concerning to see so many varieties sold in the U.K. breaching food safety regulations,” said Manoj Menon, environmental soil scientist in the Department of Geography at the University of Sheffield and lead author of the study.

“Rice products are often considered a safe option for babies and young children, but our research suggests that for more than half of the rice we sampled, infants should be limited to just 20 grams per day to avoid risks associated with arsenic. The government and the European Commission must introduce labelling to warn people of arsenic levels in rice to enable families to make informed food choices.”

Arsenic concentrations in rice
Fifty-five different rice types were purchased from various retailers and online suppliers in the U.K. from August to September 2018. Six were wild rice, 36 were white rice, 13 were brown or unpolished, 16 were organic rice and 39 packs were non-organic. Out of these samples, 20 did not contain specific information on country of origin.

Total arsenic in the 55 rice samples analyzed ranged from 0.01 to 0.37 mg per kg with an average of 0.15 mg per kg. A total of 42 rice samples with total arsenic above 0.1 mg per kg were seleced for arsenic speciation.

The concentrations of inorganic arsenic and organic arsenic in the 42 rice types analyzed ranged from 0.065 to 0.286 and 0.009 to 0.203 mg per kg, respectively. The average inorganic arsenic concentration of the 28 samples above the limit was 0.152 mg per kg.

Researchers considered three scenarios for the health risk assessment of rice arsenic. The first was based on the reported per capita consumption rate of rice in the U.K. and the mean inorganic arsenic concentration of the 42 rice samples examined.

In the second and third scenarios, they calculated the maximum permissible per capita consumption rates of rice for three age groups to avoid health risks. To avoid carcinogenic risks for men, women and infants, the scenarios showed a weekly maximum consumption rate of 0.301, 0.252 and 0.0322 kilograms for these three groups, respectively.

Scientists called for labelling to warn the public about levels of arsenic in rice.

“We recommend that consumers could be better informed whether rice and rice products are suitable for infants and young children up to 5 years in the product description labels.”