Each Week According to scientists, humans around the world are swallowing and inhaling enough plastic to make a credit card every week. Researchers say most of it comes from ‘microplastic’ particles in our food and drinking water. People ingest about 2,000 such particles each week, adding up to about five grams of plastic – equivalent to a credit card. Bottled and tap water are the biggest sources of microplastics, along with shellfish. Scientists are currently studying the potential health effects of ingesting so much plastic. How much bottled water do you consume in a week? Are you concerned about how much plastic waste we generate?