Researchers suggest that rising levels of humanmade chemicals, accumulating in marine plankton, might be used to monitor the impact of human activity on ecosystem health and perhaps study links between ocean pollution and land-based rates of childhood and adult chronic illnesses.Researchers suggest that rising levels of humanmade chemicals, accumulating in marine plankton, might be used to monitor the impact of human activity on ecosystem health and perhaps study links between ocean pollution and land-based rates of childhood and adult chronic illnesses.