> Japan says all radioactive elements have been filtered out except tritium, which is hard to remove from water. The hydrogen isotope is also discharged – at higher levels – by operational nuclear power plants, including in China and France.<p>> That water will contain about 190 becquerels of tritium per litre, below the World Health Organization drinking water limit of 10,000 becquerels per litre, according to Tepco. A becquerel is a measure of radioactivity.<p>> Monitors from the International Atomic Energy Agency (IAEA), which has backed the plan, will be on-site for the discharge, and samples of water and fish will be taken.<p>Umm, what's the controversy here?