The same newspaper article reported that a study by the Puerto Rico Health Department cited high levels of heavy metals in plants, animals and humans and that high levels of heavy metals appear to be causing increased cancer and infant mortality rates, and childhood asthma. In the live impact range on the eastern tip of island, studies have shown that the ground water is contaminated by nitrates and explosives. Furthermore, unexploded weapons, ordnance, and sunken barges litter the floor of the Caribbean Sea. Testing done in the Icacos Lagoon showed concentrations of cadmium in crabs to be 1,000 times higher than the World Health Organization's "tolerable ingestion maximum dosage." Furthermore, toxic levels of heavy metals, including lead, arsenic, selenium, mercury and zinc, have been found in several species of fish. In the lawsuit conducted by environmentalists and the people of Vieques against the Navy, the prosecutors noted that most residents of Vieques use many of these same species of fish as a source of food. Cadmium and arsenic are carcinogenic. One study from 1999 that tested hair samples from various age groups of Vieques residents revealed that 69% were contaminated with cadmium and arsenic, and 34% had toxic levels of mercury.