Lead and water: reaction mechanisms, environmental impact and health effects

Seawater contains trace amounts of lead (2-30 ppt). On average rivers contain between 3 and 30 ppb. Phytoplankton contains approximately 5-10 ppm lead (dry mass), freshwater fish approximately 0.5-1000 ppb, and oyster approximately 500 ppb.
The World Health Organization (WHO) stated a legal limit of 50 ppb for lead in 1995, which is decreased to 10 ppb in 2010.