Heavy metal content of rice meals sold in a Nigerian market population with a high prevalence of hypertension.

Context: Some market populations in Nigeria have been shown to have high prevalence of hypertension. Current evidence includes environmental pollutants such as heavy metals as risk factors for hypertension.

Aim: To study the heavy metal content of rice meals sold in a market population with a high prevalence of hypertension.

Settings And Design: This was a descriptive, cross-sectional study conducted in Ogbete market in Enugu, Southeast Nigeria.

Subjects And Methods: Five different cooked rice meals were obtained from 25 locations of the market. The rice meals included jollof rice, white rice and tomato stew, fried rice, white rice and vegetable sauce, and white rice and palm oil stew (ofeakwu). Accompanying protein (meat, fish, and egg) and vegetable salad were excluded. Similar rice meals were homogenized and analyzed in triplicates using spectrophotometric methods for mercury, copper, cadmium, lead, and arsenic determination.

Statistical Analysis Used: The mean concentrations of the heavy metals were compared using analysis of variance, and P < 0.05 was considered statistically significant.

Results: Twenty-five rice dishes were evaluated, five of each kind. Arsenic content ranged from 503 to 550 mg/kg and was comparable across the five rice dishes (P = 0.148). Copper was significantly highest (16767 mg/kg) in the white rice and tomato stew dish (P < 0.001), while mercury was significantly highest (33 mg/kg) in white rice and ofeakwu (P < 0.001). Jollof rice had the highest cadmium content (23 mg/kg), which was statistically significant (P = 0.021). Lead was not found in any of the rice dishes.

Conclusions: Risk factors such as heavy metals may play a role in the high prevalence of hypertension observed in market populations, and rice meals may be a major source of these heavy metals.