BPA-free plastic may host BPA-like chemical, teen finds
LOS ANGELES, Calif. — Most people probably don’t think much about what is in the plastics they use. But Anna Kucera, 16, did. Bisphenol A, or BPA, is a building block of the clear, hard plastics long used in many products, especially water bottles. But when health concerns about BPA emerged, many companies began making their clear plastic with other substances. And that made the junior at Canterbury School in Fort Myers, Fla., wonder what replaced the BPA in “BPA-free” plastics. With a bit of chemistry, she now shows that in some plastics, BPA has been replaced with one of its potentially toxic chemical cousins. Known as bisphenol F, or BPF, this other chemical leaches out of those plastics at amounts 10 times higher than the levels that leach from BPA-based plastics.
The teen showed off the results of her project at the Intel International Science and Engineering Fair, or ISEF. The competition brought together 1,800 high school students from around the world to show off their research this year. (ISEF was created by Society for Science & the Public and is sponsored by Intel. SSP also publishes Science News for Students and this blog.)
Many hard clear plastic products used for eating, drinking or with kitchen appliances are made from polycarbonate. BPA is this plastic's basic building block. Studies have shown BPA can leach out of heated water bottles or the paper for store receipts. BPA can then enter the body. There, its acts as an endocrine disruptor. That means that it mimics the actions of hormones — chemicals from glands that play important roles throughout the body.
Now, it is common to find plastics labeled as “BPA-free.” Anna wondered what they were made from. “There are so many bottles that are ‘BPA-free.’ They must substitute something for the BPA because they look exactly the same,” she says. She read that BPA might be replaced with other endocrine disruptors, such as BPF and bisphenol S (BPS).
The teen decided to investigate what was in those BPA-free bottles. She purchased 10 plastic water bottles labeled “BPA-free” and 10 bottles that didn’t have the label. “I assumed if there was no BPA-free designation they possibly could use BPA, because it’s generally a common thing to use,” Anna says. For her control, she purchased 10 glass bottles.
Working with her father Paul Kucera and chemist Daniel Paull at Florida Gulf Coast University in Fort Myers, the teen filled her bottles with a chemical called acetonitrile (Ah-SEE-tow-NY-tryle). It is a solvent, or a material into which other chemicals dissolve. She put her filled bottles in a tub of water at 55° Celsius (131° Fahrenheit) for 72 hours.
Then she ran the fluid from inside the bottles through a gas chromatograph linked to a mass spectrometer. A gas chromatograph separates chemicals in a mix. The mass spectrometer identifies them. Anna hunted for BPA, BPS and BPF in her samples.
None of her samples had any BPS. The fluid from bottles that had no BPA-free label did have some BPA, about 0.440 parts per million, or around 0.44 milligram (0.000015 ounce) of BPA per liter (0.26 gallon) of water. That’s would be equal to dissolving about 1 kilogram (2.2 pounds) of BPA in an Olympic swimming pool.
The fluid from BPA-free bottles had no measurable BPA. But they did contain a lot of BPF. Anna measured about 4.7 milligrams (0.00016 ounce) per liter (0.26 gallon) of BPF in the acetonitrile that had been in those bottles. That’s 10 times as the amount of BPA that had leached into the fluid from the bottles that weren’t BPA-free. “What [the manufacturers are] doing is substituting something very similar for BPA,” she says.
A chemical extraction may get some of the BPF out of the water bottle. But that doesn’t necessarily mean that BPF would leach out of a plastic bottle and into someone’s water at the same concentrations. However, Anna is worried. BPS has been shown to cause health problems in rats and zebrafish. And studies affex sex-hormone levels in human cells and can mimic estrogen in zebrafish. “It may not be safe to believe that a BPA-free bottle is any better than an ordinary plastic bottle,” the teen says. “There’s quite a lot of BPF [leaching out].”
Anna hopes that chemists will find another chemical to use in plastics. “If they could find something that could achieve the same thing, but was a better substitution that was more environmentally friendly,” she says. “That would be much better.”
The teen may hunt for that new chemical herself. Anna wants to be a chemical engineer. In the meantime, she won’t drink out of plastic. “I prefer glass,” she says. “It’s always the best alternative because nothing can be extracted from a glass bottle.”
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acetonitrile Also known as methyl cyanide, this compound is a colorless liquid that dissolves in both water and alcohol. It’s used as a solvent, to help other materials dissolve into such materials. The chemical is highly reactive and fairly toxic.
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. Depending on their size, animals are made of anywhere from thousands to trillions of cells. Most organisms, such as yeasts, molds, bacteria and some algae, are composed of only one cell.
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.
chemical engineer A researcher who uses chemistry to solve problems related to the production of food, fuel, medicines and many other products.
chemistry The field of science that deals with the composition, structure and properties of substances and how they interact. Scientists use this knowledge to study unfamiliar substances, to reproduce large quantities of useful substances or to design and create new and useful substances. (about compounds) Chemistry also is used as a term to refer to the recipe of a compound, the way it’s produced or some of its properties. People who work in this field are known as chemists.
control A part of an experiment where there is no change from normal conditions. The control is essential to scientific experiments. It shows that any new effect is likely due only to the part of the test that a researcher has altered. For example, if scientists were testing different types of fertilizer in a garden, they would want one section of it to remain unfertilized, as the control. Its area would show how plants in this garden grow under normal conditions. And that gives scientists something against which they can compare their experimental data.
dissolve To turn a solid into a liquid and disperse it into that starting liquid. (For instance, sugar or salt crystals, which are solids, will dissolve into water. Now the crystals are gone and the solution is a fully dispersed mix of the liquid form of the sugar or salt in water.)
endocrine disruptor A substance that mimics the action (sometimes well, sometimes poorly) of one of the body’s natural hormones. By doing this, the fake hormone can inappropriately turn on, speed up or shut down important cellular processes.
engineer A person who uses science to solve problems. As a verb, to engineer means to design a device, material or process that will solve some problem or unmet need.
engineering The field of research that uses math and science to solve practical problems.
estrogen The primary female sex hormone in most higher vertebrates, including mammals and birds. Early in development, it helps an organism develop the features typical of a female. Later, it helps a female’s body prepare to mate and reproduce.
Food and Drug Administration (or FDA) A part of the U.S. Department of Health and Human Services, FDA is charged with overseeing the safety of many products. For instance, it is responsible for making sure drugs are properly labeled, safe and effective; that cosmetics and food supplements are safe and properly labeled; and that tobacco products are regulated.
gland A cell, a group of cells or an organ that produces and discharges a substance (or “secretion”) for use elsewhere in the body or in a body cavity, or for elimination from the body.
hormone (in zoology and medicine) A chemical produced in a gland and then carried in the bloodstream to another part of the body. Hormones control many important body activities, such as growth. Hormones act by triggering or regulating chemical reactions in the body. (in botany) A chemical that serves as a signaling compound that tells cells of a plant when and how to develop, or when to grow old and die.
Intel International Science and Engineering Fair (Intel ISEF) Initially launched in 1950, this competition is one of three created (and still run) by the Society for Science & the Public. Each year now, approximately 1,800 high school students from more than 75 countries, regions, and territories are awarded the opportunity to showcase their independent research at Intel ISEF and compete for an average of $4 million in prizes.
leach (in geology and chemistry) The process by which water (often in the form of rain) removes soluble minerals or other chemicals from a solid, such as rock, sand, soil, trash or ash.
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.
sex An animal’s biological status, typically male or female. There are a number of indicators of biological sex, including sex chromosomes, gonads, internal reproductive organs, and external genitals.
Society for Science & the Public This nonprofit organization was created in 1921 and is based in Washington, D.C. Since its founding, SSP has been not only promoting public engagement in scientific research but also the public understanding of science. It created and continues to run three renowned science competitions: The Regeneron Science Talent Search (begun in 1942), the Intel International Science and Engineering Fair (initially launched in 1950) and Broadcom MASTERS (created in 2010). SSP also publishes award-winning journalism: in Science News (launched in 1922) and Science News for Students (created in 2003). Those magazines also host a series of blogs (including Eureka! Lab).
solvent A material (usually a liquid) used to dissolve some other material into a solution.
spectrometer An instrument that measures a spectrum, such as light, energy, or atomic mass. Typically, chemists use these instruments to measure and report the wavelengths of light that it observes. The collection of data using this instrument, a process is known as spectrometry, can help identify the elements or molecules present in an unknown sample.
zebrafish A small tropical freshwater fish belonging to the minnow family. Zebrafish are used frequently in scientific research because they grow quickly and their genetic makeup is well understood.