Exposure to the global rice trade: A comparative study of arsenic and cadmium in rice consumed in Haiti

Abstract

Rice makes up nearly a quarter of dietary intake in Haiti. Rice consumption began to rapidly increase during the mid-1980s and 1990s, corresponding to policy interventions that promoted the importation and consumption of U.S.-grown rice, soon making Haiti the second largest export market for Ameri­can rice worldwide. Haitian growers also cultivate and sell local rice. Rice consumption can be a significant source of exposure to toxic metals since rice plants accumulate arsenic and cadmium from their envi­ronment. In August 2020, we collected samples of local (n=48) and imported (n=50) rice from vendor sites in the Lower Artibonite Valley region of Haiti. Cadmium and arsenic concentrat­ions were meas­ured via inductively coupled plasma mass spec­trom­e­try. Levels were compared between local versus imported commercial rice samples. For arsenic, we conducted a simulation study to esti­mate the intake of arsenic from varied quantities of local or imported rice samples on a per-body weight basis for adults and young children. We found that median concentrations were nearly two-fold higher for both arsenic and cadmium in im­ported rice (0.15 µg/g and 0.007 µg/g) compared to local rice (0.07 µg/g and 0.003 µg/g). Our simu­lation of arsenic intake through rice consumption suggests that adults of varying weights consuming 3 or more cups of imported rice per day would exceed a daily minimum risk level for toxicity. The simulation also suggests that most children con­suming 1 or more cups of local or imported rice per day would exceed a health-based arsenic intake limit. In Haiti, imported rice had an average level of arsenic twice that of locally grown product, with some imported sources exceeding the international limits recommended to protect human health. Cur­rent consumption patterns of imported rice over the long-term for children and adults may adversely impact health in Haiti. Strengthening community food systems can promote better health.