What levels of mercury are safe for plants and animals that live in Canadian waters?
The Canadian Water Quality Guideline (CWQG) to protect freshwater life is 26 nanograms of inorganic mercury per litre of water (in other words, 26 parts per trillion). For methylmercury, the interim CWQG is 4 nanograms per litre of water. These freshwater guidelines are based on many scientific studies that examined the impacts of mercury on plants, invertebrates, and fish that live in our lakes and rivers. The methylmercury interim guideline is recommended for direct exposure to methylmercury in water. It may not protect freshwater animals that are exposed to methylmercury through their food. The interim CWQG to protect marine life is 16 nanograms of inorganic mercury per litre of water. This marine guideline is based on scientific studies that examined the impacts of mercury on plants and animals that live in our estuaries and along our coasts. We did not have enough information to calculate a marine guideline for methylmercury. If the levels of inorganic mercury and methylmercury me
