'No immediate plan' to reduce nitrate levels - Parker 22 Feb, 2021 11:45 PM 3 minutes to read Environment Minister David Parker. Photo / RNZ - Dom Thomas RNZ The Environment Minister says New Zealand will continue to follow WHO guidelines on nitrate levels in the water despite international research finding much lower levels could still cause cancer. The first study into the country's nitrate in drinking water says one in six people could be drinking water polluted enough to cause colorectal cancer. The research, overseen by Victoria and Otago Universities, calls for action from the horticulture and dairy industries. Advertisement The study used overseas research including a major Danish study that found a link with bowel cancer when levels were as low as 0.87mg/L of water.