The World Health Organization says levels of plastic in drinking water present a low risk to health, but need more research. On Thursday, the WHO released a report on microplastics, particles smaller than five millimeters. Bruce Gordon is the WHO’s coordinator for water, sanitation and hygiene. He said one of the main findings of the report is: “If you are a consumer drinking bottled water or tap water, you shouldn’t necessarily be concerned.” However, Gordon said that the available information is “weak” and that more research is needed. He also urged a greater effort to reduce plastic pollution. Andrew Mayes teaches chemistry at Britain’s University of East Anglia. He was not part of the WHO study. He said that microplastics did not appear to be a health worry for now. But he added that stronger measures are needed to reduce plastic waste.