According to a 2005 study, the average lead concentration of cocoa beans is ≤ 0.5 ng/g, which is one of the lowest reported values for a natural food. However, during cultivation and production, chocolate may absorb lead from the environment (such as in atmospheric emissions of leaded gasoline, which is still being used in Nigeria). Reports from 2014 indicate that "chocolate might be a significant source" of lead ingestion for children if consumption is high (with dark chocolate containing higher amounts), and "one 10 g cube of dark chocolate may contain as much as 20% of the daily lead oral limit."