‘Nonstick’ chemicals may undercut value of vaccinations | Science News for Students

‘Nonstick’ chemicals may undercut value of vaccinations

Immunizations may actually fail to protect children with the highest exposures
Jan 24, 2012 — 5:10 pm EST
waterproof fabric

Many water- and stain-resistant fabrics have been treated with perfluorinated chemicals, such as PFOA and PFOS. But the production of those chemicals can pollute the environment — and people. New data show human exposures can compromise the ability of vaccines to work well.

ze_pedro/iStockphoto

Many water- and stain-resistant fabrics have been treated with perfluorinated chemicals, such as PFOA and PFOS. But the production of those chemicals can pollute the environment — and people. New data show human exposures to these chemicals can compromise the ability of vaccines to work well.

ze_pedro/iStockphoto

Studies have shown that nearly everyone today carries traces of nonstick chemicals — ones known as PFOA and PFOS — in their bodies. A new study in children has now linked low blood levels of these with a reduced ability of vaccinations to do their job. Vaccines should trigger the body to make disease-fighting antibodies. In kids with the highest PFOA and PFOS exposures, this didn’t appear to happen.

“We were shocked, to be frank, in the magnitude of the effect,” says Philippe Grandjean. He’s a doctor at the Harvard School of Public Health in Boston, Mass. He also was part of a research team that described these data January 25 in the Journal of the American Medical Association.

The nonstick pollutants belong to a class of chemicals called perfluorinated (Per-FLUOR-ih-NAY-ted) compounds, or PFCs. Coating frying pans and cookie sheets with them them can keep foods from sticking. Fabrics treated with them can resist water and stains. Many older treatments were marketed under such trade names as Teflon and Scotchgard.

The chemicals worked well. But making them allowed PFCs to enter the air and water. Because the chemicals don’t break down easily, they have built up in the environment. Today, PFCs taint air, water, food, wildlife — and people.

For its new study, Grandjean’s group followed 587 children from before birth through age 7. All lived in Denmark’s Faroe Islands (about midway between Norway and Iceland). The researchers measured PFCs in the blood of the kids’ moms during pregnancy. Later, they measured PFCs in the children at ages 5 and 7. Blood levels of the chemicals were about the same — or lower — than what has been seen in most Americans, Grandjean points out.

The Faroese kids received standard childhood vaccinations. Vaccines work by revving up the body’s immune system to make antibodies. Those antibodies should later help fight germs that could trigger a particular disease. To test how well the vaccines worked, the researchers measured antibody levels in babies. They measured them again before and after the kids got booster shots at age 5.

Kids with the highest PFC levels in their bodies tended not to have responded as expected to the vaccines. The one-third of children having the highest levels of PFOA, PFOS and a third related compound (one that goes by the nickname PFHxS) commonly showed an “inadequate response to the vaccinations,” Grandjean says. In such cases, he adds, “we can’t rely on a vaccine as being effective.”

Explains Grandjean, these data suggest the immune system is not working as it should in these kids. This now raises questions about whether these children will also be more vulnerable to allergy, asthma and other diseases.

Margie Peden-Adams is a toxicologist at the University of Nevada, Las Vegas. She was impressed by the new study’s findings. "Those of us in the field will be excited to see it,” she told Science News.

The immune system is one of the most sensitive to toxic risks, she says. In rodent tests, her team showed that PFOS exposures to the fetus and to adults cut antibody production in response to foreign substances (such as germs).

Emanuela Corsini of the University of Milan in Italy and her colleagues have done related studies in cells. And they saw related problems. Their tests turned up two different mechanisms for the apparent toxic effects of PFOA and PFOS on immunity.

Today, many PFC manufacturers have stopped using or are voluntarily phasing out both PFOA and PFOS, Corsini notes. Still, she outs out, these chemicals remain “of toxicological concern.” After all, she explains, because they don’t break down in the environment, they remain available to be picked up by foods and water. Moreover, their resistance to breakdown means the PFCs that an animal may pick up can later be transferred intact to any animal — including people — that might eat it.

Power Words

(for more about Power Words, click here)

allergy     The inappropriate reaction by the body’s immune system to a normally harmless substance. Untreated, a particularly severe reaction can lead to death.

antibody     Any of a large number of proteins that the body produces as part of its immune response. Antibodies neutralize, tag or destroy viruses, bacteria and other foreign substances in the blood.

asthma     A disease affecting the body’s airways, which are the tubes through which animals breathe. Asthma obstructs these airways through swelling, the production of too much mucus or a tightening of the tubes. As a result, the body can expand to breathe in air, but loses the ability to exhale appropriately. The most common cause of asthma is an allergy. Asthma is a leading cause of hospitalization and the top chronic disease responsible for kids missing school.

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.

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 when two or more chemical elements unite (bond) in fixed proportions. For example, water is a compound made of two hydrogen atoms bonded to one oxygen atom. Its chemical symbol is H2O.

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.

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.

germ     Any one-celled microorganism, such as a bacterium or fungal species, or a virus particle. Some germs cause disease. Others can promote the health of more complex organisms, including birds and mammals. The health effects of most germs, however, remain unknown.

Iceland     A largely arctic nation in the North Atlantic, sitting between Greenland and the western edge of Northern Europe. Its volcanic island was settled between the late 800s and 1100 by immigrants from Norway and Celtic lands (ones governed by the Scots and Irish). It is currently home to roughly a third of a million people.

immune     Able to ward off a particular infection. Alternatively, this term can be used to mean an organism shows no impacts from exposure to a particular poison or process. More generally, the term may signal that something cannot be hurt by a particular drug, disease or chemical.

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.

immunity     The ability of an organism to resist a particular infection or poison by providing cells to remove, kill or disarm the dangerous substance or infectious germ.

mechanism     The steps or process by which something happens or “works.” It may be the spring that pops something from one hole into another. It could be the squeezing of the heart muscle that pumps blood throughout the body. It could be the friction (with the road and air) that slows down the speed of a coasting car. Researchers often look for the mechanism behind actions and reactions to understand how something functions.

PFCs     (PFCs) A family of chemically related compounds used to make products resist stains, oils and water. Among the best-known are PFOA (perfluorooctanoic acid) and PFOS (perfluorooctane sulfonate). These have been used in “nonstick” cookware, stain-resistant carpeting, food packaging and waterproof clothes. Some are even used in fire-fighting chemicals (such as foams). All are based on molecules with a carbon backbone to which fluorine atoms are bound. These potentially toxic compounds are remarkably stable. That helps them resist breakdown, which allows them to persist for years (potentially centuries) in the environment.

pollutant     A substance that taints something — such as the air, water, our bodies or products. Some pollutants are chemicals, such as pesticides. Others may be radiation, including excess heat or light. Even weeds and other invasive species can be considered a type of biological pollution.

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.

rodent     A mammal of the order Rodentia, a group that includes mice, rats, squirrels, guinea pigs, hamsters and porcupines.

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.

toxicologist     A scientist who investigates the potential harm posed by physical agents in the environment. These may include materials to which we may be intentionally exposed, such as chemicals, cigarette smoke and foods, or materials to which we are exposed without choice, such as air and water pollutants. Toxicologists may study the risks such exposures cause, how they produce harm or how they move throughout the environment.

vaccine     A biological mixture that resembles a disease-causing agent. It is given to help the body create immunity to a particular disease. The injections used to administer most vaccines are known as vaccinations.

Citation

Journal: E. Corsini et al. In vitro evaluation of the immunotoxic potential of perfluorinated compounds (PFCs). Toxicology and Applied Pharmacology. Vol. 250, January 15, 2011, p. 108. doi: 10.1016/j.taap.2010.11.004. 


Journal: P. Grandjean et al. Serum vaccine antibody concentrations in children exposed to perfluorinated compounds. Journal of the American Medical Association. Vol. 307, January 25, 2012, p. 391. doi: 10.1001/jama.2011.2034.

Journal: M.M. Peden-Adams et al. Suppression of humoral immunity in mice following exposure to perflulorooctane sulfonate. Toxicological Sciences. Vol. 104, July 2008, p. 144. doi: 10.1093/toxsci/kfn059. 

Website: U.S. Environmental Protection Agency. Basic Information about Per- and Polyfluoroalkyl Substances (PFASs): Includes Information on Perfluorooctanoic Acid (PFOA), Perfluorooctyl Sulfonate (PFOS), and All Other PFASs, and on PFCs.

Website: National Institute of Environmental Health Sciences. Perfluorinated Chemicals (PFCs) homepage.