Plastic taints most bottled water, study finds | Science News for Students

Plastic taints most bottled water, study finds

Researchers don’t know whether drinking the microplastic bits might pose health risks
Apr 23, 2018 — 6:45 am EST
water bottles

In recent tests, bottled water from nine countries contained tiny plastic bits. The microscopic pieces may come from a variety of sources including cosmetics, clothing and packaging materials.


Tiny plastic bits contaminate bottled water sold around the world, a new study finds. For now, scientists can only guess at the source of the plastic. Whether ingesting it might pose any risk also remains unknown.

Researchers tested more than 250 bottles of water. They came from nine countries and were sold under 11 different brands. These included Nestle Pure Life, Aquafina, Dasani, Evian, San Pellegrino and Gerolsteiner. Plastic turned up in 93 out of every 100 of the bottles.

Each tainted liter (almost one quart) held an average of 10 particles wider than a human hair, along with 300 smaller particles. But some bottles contained more — thousands of the floating specks. These really tiny bits are often referred to as microplastic fibers. 

Many of these particles “are small enough to be transported through our bodies and end up in our organs,” says Sherri Mason. She is a chemist at the State University of New York in Fredonia.

Mason and her team tested the water on behalf of Orb Media, a nonprofit journalism group based in the United States. Orb Media’s partners include the British Broadcasting Corporation (BBC) and the Canadian Broadcasting Corporation (CBC). Both of those outlets published stories about the research last month. To date, the results have not yet been peer reviewed or published in a scientific journal. The researchers did, however, post details of their study online March 14.

A continuing problem

Plastic pollution in the environment is nothing new. Tiny bits of plastic have turned up in rivers, lakes and oceans. Finding them has been easy. Figuring out their source has been harder.

Microplastics in water can come from larger pieces of plastic that break down in landfills and oceans. Sunlight and ocean waves also help break up pieces of plastic. Even clothes can shed microplastics. Fabrics such as fleece and nylon are made from plastic. When washed, they shed bits of plastic lint. It travels from the wash water down household drains and eventually into rivers, lakes and oceans.  

Other microplastic beads go in some toothpastes and skin-care products. These beads help scrub away tooth plaque and dead skin cells. Then they, too, wash down the drain.

The most common type of plastic that Mason and her team found in bottled water was polypropylene (Pah-lee-PROH-puh-leen). This is the same type used in bottle caps. They also found bits of nylon and polyethylene terephthalate (Pah-lee-ETH-uh-leen Tair-eh-THAAL-ayt), also known as PET. PET is the main plastic used in water bottles.

So how do they get into bottled water? Once plastic bits go down the drain, it will wash into — and then out of — water treatment plants (because they were not designed to filter the plastics out). These facilities release their water into rivers and the ocean. Some of that water may move into groundwater, which some companies use for bottled water. Other companies may use city tap water. And earlier studies had found plastic bits could come out in tap water. The source of that plastic, too, might be contaminated lakes or rivers.

The new study is the first to find microplastics in bottled water, its authors say. In fact, Mason notes, her team found at least twice as many particles in bottled water as earlier tests had found in tap water.

Scientists aren’t sure what ingesting the tiny bits of plastic might do to our health. “But we know it probably isn’t good,” Mason says.

Plastics are made from many types of chemicals. There isn’t yet enough research to know how many of these might affect human health. After all, they were never designed to be eaten. Plastic also acts like a sponge, soaking up many types of chemicals. For example, pesticides and other toxic compounds have been found in plastics floating in the ocean. So plastic particles might ferry such pollutants into bottled water, too.

Dyes mark the plastic

Andrew Mayes is a chemist in England at the University of East Anglia, in Norwich. This is the largest study of bottled water he says he’s ever seen. “The main message from the study is that microplastics are all around us,” says Mayes. And, he adds, they “are getting into everything we eat, drink and probably breathe.”

Mayes helped to develop the method Mason and her team used to detect the microplastics. He has now reviewed how Mason’s group did its research and agrees with its findings.

Here’s what they did. They added a dye known as Nile Red to the bottled water. That dye sticks to plastic surfaces. (Some of the dye stuck to the insides of the bottles, too.) When viewed under blue light, the dye will glow. The researchers then poured the bottled water through a special type of paper. Water flows right through it, but larger molecules such as plastic get caught on the paper’s surface. The researchers put that paper under a microscope and shone a blue light on it. Then they counted the glowing plastic bits.

Story continues below image.

microplastic specks in bottled water
If you look closely at the bottle on the right, you can see bright specks. Those are tiny bits of floating plastic. They were labeled with a dye that glows under a certain wavelength of light.
Orb Media

“It’s a bit like the glow-in-the-dark stars many kids have on their ceilings,” says Mason. “We counted the bright spots.”

The new study doesn’t say where the plastic bits in bottled water are coming from, Mayes notes. But it’s possible, he says, that they come from the bottle caps or the bottles themselves during processing and packing.

Mason worries that more and more plastic is turning up in the environment. Part of the problem, she says, is that we use a lot of disposable plastic. Plastic bags, bottles and straws are the major culprits.

“Say 'no' to straws, because they suck,” Mason recommends. “And don’t use plastic bags for wrapping sandwiches. There are reusable products you can use instead.”

Power Words

(more about Power Words)

average     (in science) A term for the arithmetic mean, which is the sum of a group of numbers that is then divided by the size of the group.

cell     The smallest structural and functional unit of an organism. Typically too small to see with the unaided eye, it consists of a watery fluid surrounded by a membrane or wall.

chemical     A substance formed from two or more atoms that unite (bond) in a fixed proportion and structure. For example, water is a chemical made when two hydrogen atoms bond to one oxygen atom. Its chemical formula is H2O. Chemical also can be an adjective to describe properties of materials that are the result of various reactions between different compounds.

environment     The sum of all of the things that exist around some organism or the process and the condition those things create. Environment may refer to the weather and ecosystem in which some animal lives, or, perhaps, the temperature and humidity (or even the placement of components in some electronics system or product).

filter     (in chemistry and environmental science) A device or system that allows some materials to pass through but not others, based on their size or some other feature. (in physics) A screen, plate or layer of a substance that absorbs light or other radiation or selectively prevents the transmission of some of its components.

journal     (in science) A publication in which scientists share their research findings with experts (and sometimes even the public). Some journals publish papers from all fields of science, technology, engineering and math, while others are specific to a single subject. The best journals are peer-reviewed: They send all submitted articles to outside experts to be read and critiqued. The goal, here, is to prevent the publication of mistakes, fraud or sloppy work.

landfill     A site where trash is dumped and then covered with dirt to reduce smells. If they are not lined with impermeable materials, rains washing through these waste sites can leach out toxic materials and carry them downstream or into groundwater. Because trash in these facilities is covered by dirt, the wastes do not get ready access to sunlight and microbes to aid in their breakdown. As a result, even newspaper sent to a landfill may resist breakdown for many decades.

media     (in the social sciences) A term for the ways information is delivered and shared within a society. It encompasses not only the traditional media — newspapers, magazines, radio and television — but also Internet- and smartphone-based outlets, such as blogs, Twitter, Facebook and more. The newer, digital media are sometimes referred to as social media. The singular form of this term is medium.

microplastic     A small piece of plastic, 5 millimeters (0.2 inch) or smaller in size. Microplastics may have been produced at that small size, or their size may be the result of the breakdown of water bottles, plastic bags or other things that started out larger.

microscope     An instrument used to view objects, like bacteria, or the single cells of plants or animals, that are too small to be visible to the unaided eye.

molecule     An electrically neutral group of atoms that represents the smallest possible amount of a chemical compound. Molecules can be made of single types of atoms or of different types. For example, the oxygen in the air is made of two oxygen atoms (O2), but water is made of two hydrogen atoms and one oxygen atom (H2O).

nylon     A silky material that is made from long, manufactured molecules called polymers. These are long chains of atoms linked together.

organ     (in biology) Various parts of an organism that perform one or more particular functions. For instance, an ovary is an organ that makes eggs, the brain is an organ that makes sense of nerve signals and a plant’s roots are organs that take in nutrients and moisture.

particle     A minute amount of something.

peer review    (in science) A process in which scientists in a field carefully read and critique the work of their peers before it is published in a scientific journal. Peer review helps to prevent sloppy science and bad mistakes from being published.

pesticide     A chemical or mix of compounds used to kill insects, rodents or other organisms harmful to cultivated plants, pets or livestock; or unwanted organisms that infest homes, offices, farm buildings and other protected structures.

plaque     (in dental medicine) A biofilm, or community of bacterial species, that grows on teeth and other surfaces in the mouth.

plastic     Any of a series of materials that are easily deformable; or synthetic materials that have been made from polymers (long strings of some building-block molecule) that tend to be lightweight, inexpensive and resistant to degradation.

polyethylene     A plastic made from chemicals that have been refined (produced from) crude oil and/or natural gas. The most common plastic in the world, it is flexible and tough. It also can resist radiation.

polyethylene terephthalate     A commonly used type of plastic, usually referred to simply as PET. It can be produced as strong, stable fibers for use in making clothing. It also is the basis of many plastic beverage bottles (such as milk jugs) and semi-hard food packages (often used for produce). When used in fabrics, it’s simply known as polyester. To identify these plastics in goods other than clothing, they tend to carry a labeled on the bottom or side with the number 1 surrounded by the triangular "chasing arrows" symbol and the acronym PET or PETE below the triangle.

polypropylene     The second most common plastic in the world. It is tough and durable. Polypropylene is used in packaging, clothing and furniture (such as plastic chairs).

toxic     Poisonous or able to harm or kill cells, tissues or whole organisms. The measure of risk posed by such a poison is its toxicity.

United Kingdom     Land encompassing the four “countries” of England, Scotland, Wales and Northern Ireland. More than 80 percent of the United Kingdom’s inhabitants live in England. Many people — including U.K. residents — argue whether the United Kingdom is a country or instead a confederation of four separate countries. The United Nations and most foreign governments treat the United Kingdom as a single nation.


Report : S.A. Mason et al. Synthetic polymer contamination in bottled water. March 14, 2018 (online).

Journal:​ T. Maes et al. A rapid-screening approach to detect and quantify microplastics based on fluorescent tagging with Nile Red. Scientific Reports. Vol. 7, March 16, 2017. doi: 10.1038/srep44501.

Further Reading

Orb Media. “Plus plastic.”