Did your burger come with a side of non-degrading pollutants? | Science News for Students

Did your burger come with a side of non-degrading pollutants?

Non-stick chemicals that might be harmful are showing up in fast-food packaging
Mar 29, 2017 — 7:10 am EST
burger wrapper

Some fast-food wrappers contain PFCs, potentially harmful chemicals that won’t break down in the environment — or you.

Milkos/iStockphoto

One attraction of fast foods is that they’re, well, convenient. They’re ready minutes after you hit the burger joint, taco stand or fried-chicken emporium. But another aspect of their convenience is less obvious: The paper or cardboard in which they’re wrapped tends to resist absorbing liquids, including fat. So the oils used to turn chicken wings and French fries golden brown don’t bleed through onto your hands or lap. What makes this possible, in many cases, is a class of potentially toxic, long-lived chemicals. And these may live on to pollute you or the environment.

That’s the conclusion of a new study.

Here’s why they’re worrisome, says Laurel Schaider: “Some of these chemicals are thought to cause cancer, harm our immune systems, or even change the way our bodies develop as small children.” Schaider is an environmental chemist at the Silent Spring Institute in Newton, Mass. Such scientists study how chemicals can enter and move through the environment.

The chemicals that make these wrappers oil-resistant are called perfluorinated (Per-FLOOR-ih-nay-ted) compounds, or PFCs. They take their name from the fact that they’re loaded with fluorine atoms. Manufacturers have for decades been churning out huge amounts of PFCs.

Because PFCs don’t degrade, these chemicals have been accumulating throughout the environment. Scientists have found traces of them on all seven continents and in the oceans. These chemicals are not supposed to be eaten by animals or us. Yet studies have been finding them in fish and birds, polar bears and people. Indeed, at least trace amounts taint the blood of most Americans.

One way PFCs might enter the body is through food. They can rub off food wrappers and end up on someone’s fingers — or in the food itself. So for its new study, her team looked for PFCs in food packaging.

And they found evidence of plenty.

The researchers went to 27 fast food restaurants in 5 states. They collected more than 400 pieces of food packaging made from paper or cardboard. These included paper cups, wrappers for burgers and fries, pizza boxes and pastry bags. There are hundreds of different PFCs. The researchers did not identify which particular ones had been in their samples. Instead they measured the total amount of fluorine in each sample. Its presence indicates that a product likely contains PFCs, explains Schaider.

Almost half of the paper used to wrap foods like burgers or cookies contained fluorine, they found. About one in every five cardboard products also contained fluorine. Called paperboard, this thin cardboard is the somewhat stiff material used to hold foods such as fries.

Schaider’s team reported its findings March 14 in Environmental Science & Technology Letters.

Some PFCs risk altering the normal development of a fetus or a child. Those changes may include altering human growth, learning and behavior. Some PFCs can harm reproduction. At least a few PFCs can mimic — or interfere with — the body’s natural hormones. PFCs not only can impair the immune system, but also have been linked with boosting cholesterol, which is a risk factor for heart disease. Some PFCs even appear to boost cancer risks. This long list of potential health issues comes from the Agency for Toxic Substances and Disease Registry, part of the U.S. government.

Indestructible chemistry

PFCs start with linked chains of carbon atoms. This serves as the backbone of each molecule. To this, manufacturers add fluorine atoms. They bond to each carbon in the chain.

The carbon-fluorine bond is one of the strongest known. That toughness imparts special properties. PFCs don’t absorb water or oily fats. They don’t degrade with heat. And they resist breaking down in the environment. Some may survive, unchanged, for thousands of years.

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chemical structure
PFOA is one of the persistent compounds that can show up in fast-food packaging. Its chemical structure, here, starts with a chain of linked carbon atoms to which manufacturers have attached atoms of fluorine (F). PFOA has a carbon atom at the center of each “X” in this structure.
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These properties have made the chemicals attractive for a host of uses. They make some pots and pans nonstick. They turn coats and camping tents largely waterproof. They help carpets and upholstery resist stains. And they help keep the wrap on your burger and French fries from getting oily. It even keeps microwave-popcorn bags from releasing the oil used to help that corn pop.

“The downside is that we’ve manipulated the chemistry so much that nature can’t break them down,” says Terry Collins. He directs the Institute for Green Science at Carnegie Mellon University in Pittsburgh, Pa. As a “green chemist,” he looks for safer alternatives to chemicals that may be harmful, such as PFCs.  

When we throw away a cookie pouch or burger wrapper, it goes to a landfill. As the wrapper breaks down over time, any inks or other potentially toxic chemicals in it can leach into water, soil and the air. From there, these chemicals can enter the food web and get passed between organisms as they eat each other. Since the compounds don’t break down, each predator’s body will collect the PFCs that had been in its prey. The more they eat, the higher the levels of these chemicals that can end up in an animal’s body.

Collins says we need to start thinking more seriously about what goes into the products we use everyday. It may be nice to wrap up your meal in something that neither food nor water will penetrate. Yet doing so may risk adding indestructible and potentially harmful chemicals into the environment. People need to ask, he concludes: Is that convenience worth the risk?

Power Words

(for more about Power Words, click here)

atom     The basic unit of a chemical element. Atoms are made up of a dense nucleus that contains positively charged protons and uncharged neutrons. The nucleus is orbited by a cloud of negatively charged electrons.

bond     (in chemistry) A semi-permanent attachment between atoms — or groups of atoms — in a molecule. It’s formed by an attractive force between the participating atoms. Once bonded, the atoms will work as a unit. To separate the component atoms, energy must be supplied to the molecule as heat or some other type of radiation.

cancer     Any of more than 100 different diseases, each characterized by the rapid, uncontrolled growth of abnormal cells. The development and growth of cancers, also known as malignancies, can lead to tumors, pain and death.

carbon     The chemical element having the atomic number 6. It is the physical basis of all life on Earth. 

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 can also be an adjective to describe properties of materials that are the result of various reactions between different compounds.

cholesterol     A fatty material in animals that forms a part of cell walls. In vertebrate animals, it travels through the blood in little vessels known as lipoproteins. Excessive levels in the blood can signal risks to the blood vessels and heart.

colleague     Someone who works with another; a co-worker or team member.

compound     (often used as a synonym for chemical) A compound is a substance formed from two or more chemical elements that bon in fixed proportions. 

degrade     To break down into smaller, simpler materials — as when wood rots or as a flag that’s left outdoors in the weather will fray, fade and fall apart. (in chemistry) To break down a compound into smaller components.

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

fertility     Ability to reproduce.

fetus     (Adj. fetal ) The term for a mammal during its later-stages of development in the womb. For humans, this term is usually applied after the eighth week of development.

food web     (also known as a food chain ) The network of relationships among organisms sharing an ecosystem. Member organisms depend on others within this network as a source of food.

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. 

immune system     The collection of cells and their responses that help the body fight off infections and deal with foreign substances that may provoke allergies.

impair     To damage or weaken in some way.

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 landfill may resist breakdown for many decades.

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.

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).

organism     Any living thing, from elephants and plants to bacteria and other types of single-celled life.

predator     (adjective: predatory) A creature that preys on other animals for most or all of its food.

prey     (n.) Animal species eaten by others. (v.) To attack and eat another species.

risk     The chance or mathematical likelihood that some bad thing might happen. For instance, exposure to radiation poses a risk of cancer. Or the hazard — or peril — itself. Among cancer risks that the people faced were radiation and drinking water tainted with arsenic.

taint     To contaminate.

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.

NGSS: 

  • MS-PS1-1
  • MS-LS1-5
  • MS-ESS3-3
  • HS-LS2-7

Citation

Journal: LA Schaider et al. Fluorinated compounds in U.S. fast food packaging. Environmental Science & Technology Letters. Vol. 4, March 14, 2017, p. 105. doi: 10.1021/acs.estlett.6b00435.

Government Website: How can PFAs affect people’s health?” The Agency for Toxic Substances and Disease Registry. August 16, 2016.

Journal:  F. Suja, B.K. Pramanik and S.M. Zain. Contamination, bioaccumulation and toxic effects of perfluorinated chemicals (PFCs) in the water environment: A review paper. Water Science & Technology. Vol;. 60, September 2009, p. 1533. doi: 10.2166/wst.2009.504.