New research shows microplastics may be in a lot of drinking water globally, and it may end up in our organs and local academics say we are more exposed to plastics than we may think.
The World Health Organisation is calling for urgent research on the potential impacts on human health - and in the meantime for nations to crack down on plastic pollution.
"We urgently need to know more about the health impact of microplastics because they are everywhere - including in our drinking water," Dr Maria Neira said.
Dr Neira is the director for the environment and social determinants of health at WHO Department of Public Health.
"Based on the limited information we have, microplastics in drinking water don't appear to pose a health risk at current levels. But we need to find out more."
Tiny pieces of plastic from the breakdown of waste can travel through soil and into surface and groundwater, as well as breaking down in the sea and freshwater.
Local experts said it was not known how much plastic was in New Zealand's drinking water, but any health risk seemed to be less than other potential contaminants, such as bacteria and chemicals.
University of Auckland School of chemical sciences associate Professor Duncan McGillivray said: "We are more exposed to microplastics than we think. There are studies that have shown the presence of as much as 1000 particles per litre of bottled water.
"The main message from the report is not to panic about microplastics - any potential health risk appears to be much less than other potential contaminants in drinking water such as bacteria and pollutant chemicals, and treatment systems that reduce those contaminants can do a good job of dealing with microplastics as well.
"But we should not relax either - there are too many unknowns about how microplastics impact health, and the WHO report strongly encourages further research in the area."
Institute of Environmental Science and Research senior scientist, Dr Olga Pantos, said traditionally the impacts of microplastics had been focused on human exposure through seafood, but it was starting to include exposure through freshwater, land and air.
"One thing we do know is plastic is not supposed to be in the environment," she said.
"In New Zealand, groundwater and surface water are our major sources of drinking water. We do not have good information on the burden of microplastics in those environments, or how it is getting there.
"Although we do not know what the levels of microplastics are in New Zealand drinking water, based on international studies we may expect that the treatments used for the removal of microbiological contamination and turbidity of municipal supplies in New Zealand will be effective in removing microplastics."
Dr Pantos said we needed more robust testing methods to detect microplastics.
"We also know that microplastics continue to break down, creating nano plastics and the smaller they get, the greater the challenge for isolating and identifying them accurately.
"We need to reduce the amount of plastic we use. The less that ends up in the environment, the less there is to deal with, and the less there is to cause harm."