Consumer Safety: Antifreeze in Toothpaste

We’re ever thankful when our students come to school with freshly brushed teeth, but could there be a circumstance under which you would suggest your students not use toothpaste? In May of 2007, BBC News reported that the Chinese government was investigating charges that toothpaste containing diethylene glycol, also known as antifreeze, had been exported to other countries.

In the following months the New York Times, Fox News, and others identified the tainted brands of toothpaste and locations where they were sold. Some brands were found to contain the compound even though it wasn’t listed as an ingredient. Unfortunately for China, the tainted toothpaste adds to a growing list of product-safety breaches, including a similar incident with cough syrup in 2006 and, more recently, the use of lead-based paints in children’s toys.

In the United States, the Consumer Product Safety Commission provides information and issues safety alerts on consumer products. In the wake of the incidents involving lead-based paint on toys, the Commission reached an agreement with China, requiring imported toys and some other products to meet U.S. safety standards. In addition, the U.S. Food and Drug Administration got involved with the tainted toothpaste issue, developing a web page devoted to the problem.

To what extent should individuals rely solely on government agencies to look out for their personal safety? How much scientific literacy do consumers need to be able to read labels and make informed decisions regarding their own health and safety? These questions are addressed in an October 1, 2007, article in the New York Times, The Everyman Who Exposed Tainted Toothpaste. This article tells the story of how one person, Eduardo Arias, brought the issue of tainted toothpaste to the attention of the world.

Arias is a Panamanian government employee responsible for reviewing environmental reports, but that’s not the reason he recognized the compound in the list of toothpaste ingredients as toxic. Rather, he was made aware of diethylene glycol’s toxic effects when, in 2006, almost 100 people died after consuming tainted cough syrup from China, another story reported by the New York Times. Bringing the danger of the tainted toothpaste to the attention of the proper authorities required Arias to cut through the government bureaucracy at three levels and cost him a considerable amount of personal time. His story exemplifies the human side of safety in society and personalizes an issue that could easily be perceived as something the government is solely responsible for. His story should inspire others to do the right thing, despite the probable inconvenience doing so brings.

How to Turn This News Event into an Inquiry-Based, Standards-Related Science Lesson

What’s so dangerous about diethylene glycol? Why would it be used in toothpaste? How can average citizens be proactive in maintaining their own and others’ safety when it comes to consumer products? These are questions for inquiry that align with several of the National Science Education Standards in the areas of Science as Inquiry, Physical Science, and Science in Personal and Social Perspectives.

The intention here is not to scare middle school students, but to show them there are mechanisms in place to maintain our safety, and these mechanisms require active, informed, scientifically literate citizens. We all have a responsibility to stay informed. Teachers have a responsibility to assist students in learning where and how to access the needed information as well as how to evaluate it for its authenticity, validity, and usefulness. This approach provides opportunities to integrate skills and knowledge in language arts, social studies, and science.

We Want Your Feedback

We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? We invite you to share with us and other readers by posting your comments. Please check back often for our newest posts or download the RSS feed for this blog. Let us know what you think and tell us how we can serve you better. We appreciate your feedback on all of our Middle School Portal 2 publications. You can also email us at msp@msteacher.org.

This post was originally written by Mary LeFever and published October 3, 2007 in the Connecting News to the National Science Education Standards blog. The post was updated 4/23/12 by Jessica Fries-Gaither.

 

After 50 Years, Scientists Still Not Sure How DEET Works

DEET (short for N,N-diethyl-meta-toluamide) is the most widely used insect repellent in the world for a very good reason – it works really, really well! Just a quick spray on exposed skin keeps mosquitoes, flies, fleas, chiggers, and ticks away. Developed by scientists at the U.S. Department of Agriculture and patented by the U.S. Army in 1946, millions of people worldwide use DEET to ward off vector-borne diseases. First of all, why would researchers study DEET if it works so well? While DEET is an effective repellent, it doesn’t work against all bugs, it’s corrosive to plastics and there are concerns about its effect on human health.

 

Structural Formula for N, N-diethyl-meta-toluamide (DEET).
Courtesy of Wikipedia – Click on the image for a larger version.

How DEET actually works has puzzled scientists for more than 50 years. Scientists long surmised that DEET masks the smell of the host, or jams or corrupts the insect’s senses, interfering with its ability to locate a host. Mosquitoes and other blood-feeding insects find their hosts by body heat, skin odors, carbon dioxide (breath), or visual stimuli.

Amazingly, within a few months this year, scientists from two different labs have come up with competing explanations of how DEET works. In March of 2008, researchers at Rockefeller University in New York, said that DEET jams odorant receptors in insect nervous systems, in effect masking odors that would ordinarily attract the bugs. According to Dr. Leslie B. Vosshall, a researcher who worked on the project, now that they know that DEET targets OR83b co-receptors, they can quickly screen thousands of other compounds in hope of finding one that is even more effective and has fewer disadvantages.

Are you sure, ask researchers at the University of California, Davis? Mosquitoes flee because of their intense dislike for the smell of the chemical repellent and not because DEET jams their sense of smell. In August 2008, in a paper published in The Proceedings of the National Academy of Sciences, they provide a simpler explanation. Mosquitoes, they say, smell DEET directly and avoid it.

Dr. Vosshall, involved in the earlier study, said that her team stood by its work, and that its findings were based on a variety of experiments. So for now, the jury is still out.

Connecting to the National Science Education Standards

These competing explanations on how DEET works provides a perfect example of one aspect of the nature of science – Scientific Claims are Subject to Peer Review and Replication. Researchers in labs across the world work on answering many of the same questions. The results of their work are published in peer reviewed journals so that researchers around the world can examine their data and logic, identify alternative explanations, and replicate observations and experiments. Peer review is an integral part of genuine scientific enterprise and goes on continuously in all areas of science.

The National Science Education Standards in the History and Nature of Science Content Standard G describes what middle school students should understand about this part of the nature of science, including:

It is normal for scientists to differ with one another about the interpretation of the evidence or theory being considered.

Different scientists might publish conflicting experimental results or might draw different conclusions from the same data.

It is part of scientific inquiry to evaluate the results of scientific investigations, experiments, observations, theoretical models, and the explanations proposed by other scientists.

Although scientists may disagree about explanations of phenomena, about interpretations of data, or about the value of rival theories, they do agree that questioning, response to criticism, and open communication are integral to the process of science.

Additional Resources

Read the entire National Science Education Standards online for free or register to download the free PDF. The content standards are found in Chapter 6.

Science For All Americans Online: The Nature of Science
Science for All Americans consists of a set of recommendations on what understandings and ways of thinking are essential for all citizens in a world shaped by science and technology.

Household Product Database
List of products that contain DEET.

Chemical Technical Summary for Public Health and Public Safety Professionals
The Department of Health and Human Services provides a summary of all medical cases and research done on DEET.

We Want Your Feedback

We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? We invite you to share with us and other readers by posting your comments. Please check back often for our newest posts or download the RSS feed for this blog. Let us know what you think and tell us how we can serve you better. We appreciate your feedback on all of our Middle School Portal 2 publications. You can also email us at msp@msteacher.org.

This post was originally written by Kimberly Lightle and published August 26, 2008 in the Connecting News to the National Science Education Standards blog. The post was updated 4/19/12 by Jessica Fries-Gaither.

Influenza: History, Science, Strains, Detection, and Protection

Every middle school student has heard of the flu. They may even have had it, or more likely, they have had some other virus described as the flu. Most students would consider the flu unpleasant, but probably not potentially fatal. Now is a good time to help students learn more about influenza. But where do you start? I have put together some highly regarded resources on the web, designed to provide you with 1) solid background knowledge and 2) a variety of teaching resources.

A study of influenza aligns well with the Science in Personal and Social Perspectives,  Science as Inquiry, and Life Science standards of the National Science Education Standards as well as the notion of systems thinking. Perhaps the best pedagogical approach would be to start with personal and social perspectives. That way we start with the somewhat familiar and then bridge to the unfamiliar, more abstract notions of virus and epidemiology.

What Is the Flu?

Open this question up to the class and record all student responses on the board or, better yet, chart paper that can be saved and revisited later. The responses can serve as a pre-assessment or benchmark. Do not pass any judgment or offer any corrective feedback at this point. When students have run out of ideas, tell them it’s time to do a little research to find out whether what they know is accurate and complete.

Is It a Cold or the Flu?
Begin with this concise PDF from the National Institutes of Health. Page 2 is a Spanish translation. Most students will be able to relate to the listed symptoms. While both colds and the flu are caused by a virus, they are distinctly different. Is vomiting or nausea on the list? Are antibiotics listed as a treatment? Do students want to revise their chart paper list?

History and Society: What Is a Pandemic?

Below are three articles, all published up to four years before the recent swine flu outbreak, that will familiarize you with the Spanish flu pandemic of 1918. You may choose to use one of these, in perhaps a modified form, to help students get a concept of pandemic, its impact on society, and what was learned from it.

1918 Influenza: The Mother of All Pandemics

Spanish Flu of 1918: Could It Happen Again?

The 1918 Flu Killed Millions. Does It Hold Clues for Today?

The Science of Influenza

These resources will familiarize you with the more technical aspects of a virus, how the body responds, and how antiviral drugs work. You will recognize the puzzle-solving aspect of science. Observations inspire hypotheses, which are tested and tweaked as more observations are gathered.

Epidemic!
This simple simulation illustrates how quickly a virus spreads and how scientists use observations to track its origin.

The Big Picture Book of Viruses
This site contains more information than almost anyone would want. However, scroll down to see several electron micrographs of various influenza strains.

Image of bacteria cell covered in viruses
Although this is not an image of a flu virus attacking a human cell, it does give the viewer the sense of scale — that viruses are much smaller than bacteria. Be mindful that bacteria are, in turn, much smaller than our body cells.

Antibodies Neutralize Multiple Flu Strains
This March 2009 page from the National Institutes of Health reports:

Two separate scientific teams have discovered antibodies that attach to a vulnerable region in a broad range of influenza A viruses, including the H5N1 avian virus, the 1918 pandemic influenza virus, and seasonal H1N1 flu viruses. The finding could potentially help scientists develop tools to prevent or treat the flu during an outbreak or pandemic.

Antiviral Drugs and H1N1 Flu (Swine Flu)
We know that antibiotics don’t work against viruses, and up until recently we were told there was nothing we could do about viral infections but wait them out. In April of this year, the Centers for Disease Control and Prevention described the benefits of some antiviral drugs: “There are four influenza antiviral drugs approved for use in the United States (oseltamivir, zanamivir, amantadine and rimantadine). The swine influenza A (H1N1) viruses that have been detected in humans in the United States and Mexico are resistant to amantadine and rimantadine . . .”

What Is the Swine Flu?

These resources focus on the current H1N1 strain.

Q&A: Why Is Swine Flu Such a Big Deal?
This article points out that this particular strain is killing young, otherwise healthy people. Contrast that with the fact that older people and very young children are more often victims of the flu, most dying of pneumonia. That is cause for concern.

H1N1 (Swine Flu)
The official page of the Centers for Disease Control and Prevention, with updated confirmed cases and their locations. A discussion with students of the science of epidemiology would be appropriate here.

We Want Your Feedback

We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? We invite you to share with us and other readers by posting your comments. Please check back often for our newest posts or download the RSS feed for this blog. Let us know what you think and tell us how we can serve you better. We appreciate your feedback on all of our Middle School Portal 2 publications. You can also email us at msp@msteacher.org.

This post was originally written by Mary LeFever and published May 4, 2009 in the Connecting News to the National Science Education Standards blog. The post was updated 4/9/12 by Jessica Fries-Gaither.

How Many Bacteria Species Can Coexist on a Single Hand? (And do girls really have cooties?)

Sounds like a riddle, but it’s not trivial. We’ll get back to that in a minute. First consider the scenario: The class arrives from physical education. Today’s activity was mat ball, a variation of dodge ball involving lots of kids and lots of contact with balls and mats. They’re pumped, a little sweaty and out of breath, and one or two are a few seconds late—probably not because they were washing their hands! Would you have students wash their hands in this scenario? Not likely. It’s just not part of the lesson plan.

We accept a certain lack of sanitation mostly because it’s not feasible to allow 26-30 kids to wash their hands several times a day. We try to take solace in the hand sanitizers, though rumor has it there’s no substitute for warm water, soap and a minute of scrubbing.

Low-temperature electron micrograph of a cluster of E. coli bacteria, magnified 10,000 times. Each individual bacterium is oblong shaped. Photo by Eric Erbe, digital colorization by Christopher Pooley, both of USDA, ARS, EMU. Wikimedia Commons.

So what’s the big deal? Most bacteria on our skin are harmless or beneficial, right? How many could there be anyway? Well, CBCnews.ca recently published a story, Women lead men in bacteria types, hands down  that might surprise you. Researchers were surprised to find the incredible number of different bacteria species found among 51 college students’ hands and the very low number of species shared by all students. Further, there was a difference between left and right hands. And finally, there was a significant difference between men and women.

According to the news article,

They [researchers] identified 4,742 species of bacteria overall, only five of which were on every hand . . . The average hand harboured 150 species of bacteria. Not only did individuals have few types of bacteria in common, the left and right hands of the same individual shared only about 17 per cent of the same bacteria types . . .

Researchers suspect differences between left-and right-hand bacteria diversity have to do with each hand’s interactions with environment that can alter the hand’s conditions in terms of oil or salinity, for example. Differences between men and women might have to do with hormone production or slight variations in pH. Researchers commented that, for the subjects involved in this study, hand washing did not appear to remove the bacteria. It is important to note the study did not measure mass of bacteria present or population sizes for each species, only the diversity of species present.

How to Turn This News Event into an Inquiry-Based, Standards-Related Science Lesson

The National Science Education Standards Content Standard F states:

As a result of activities in grades 5-8, all students should develop understanding of

  • Personal health
  • Populations, resources, and environments
  • Natural hazards
  • Risks and benefits
  • Science and technology in society

The ideas in this news article connect to the bullets above. The following discussion highlights the ideas in the list.

Ask students if they’ve ever had a bacterial infection. What caused it? What are bacteria? Many will state they are harmful, disease causing germs. How common do they believe bacteria are? Are they in contact with any right now? How do they protect themselves against bacterial disease? Lead students to understand that many kinds of bacteria are harmless and, in fact, beneficial. Our digestion is aided by bacteria, for example. Bacteria are used in the production of yogurt and cottage cheese, among other foods. You can show them photomicrographs indicating bacteria are distinct cells, but quite small. Bacteria impact our personal health in both positive and negative ways.

How are bacteria connected to populations, resources and environments? Remind students that a group of the same kind of bacteria living in the same area is a population. Can a human hand be an adequate environment with resources to support a bacteria population? How many kinds of bacteria do you think might be able to coexist on a single human hand? Entertain all students’ guesses. Share only the numbers from the story with them. How do their guesses compare with the numbers reported?

Try some true or false questions:

1. There is no difference in the kinds of bacteria found on the same person’s right and left hand.

2. Men and women have the same kinds of bacteria on their hands.

3. Among a group of people, there is a high number of different kinds of bacteria that all people share.

Share the rest of the findings reported in the article. Ask students to generate inferences to account for the variation reported. What questions can they generate related to the findings? What kind of tests do they think would be good to conduct next and why?

You can connect the idea of natural hazards to changes in bacteria populations if you care to. After a flood for example, the biggest threat is disease due to polluted water, from overflow of sewage mixing with drinking-water supplies. At times like these, the bacteria populations found on flood-ravaged persons’ hands can be expected to differ from those found under normal conditions.

What are the risks and benefits involved in controlling bacteria through various methods: sanitation, sterilization, irradiation, and antibiotics, for example? What are the risks and benefits of using helpful bacteria to control or minimize the occurrence of harmful bacteria in food?

What role does technology play in public health policies regarding available vaccinations, medicines, and public education campaigns? See the Centers for Disease Control webpage for additional ideas and information at http://www.cdc.gov/ncidod/guidelines/guidelines_topic_bacterial.htm

To find lessons and activities that would support this topic of study, please search the MSP2 Educational Digital Library – http://www.msteacher2.org/page/search-the-msp2-collection-of?q=bacteria&action=Search. Terms such as germs or bacteria will get you started.

We Want Your Feedback

We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? We invite you to share with us and other readers by posting your comments. Please check back often for our newest posts or download the RSS feed for this blog. Let us know what you think and tell us how we can serve you better. We appreciate your feedback on all of our Middle School Portal 2 publications. You can also email us at msp@msteacher.org.

This post was originally written by Mary LeFever and published November 10, 2008 in the Connecting News to the National Science Education Standards blog. The post was updated 2/29/12 by Jessica Fries-Gaither.

Thanksgiving Science

From the pop-up thermometer to turkey genetics, Thanksgiving offers lots of topics that can be explored through science. Thanks to Terry Shiverdecker for pulling together resources from the Ohio Resource Center collection of exemplary science, mathematics, and English/language arts resources.

Along with these resources consider asking students to conduct Internet research to answer these questions:

• What is it about a traditional Thanksgiving meal that makes you sleepy? Is it the tryptophan in turkey or something else?
• What is the science behind those golden brown and delicious dinner rolls? Hint: Maillard reaction
• Does cornstarch or flour make the best gravy?

Please share any other resources/ideas/questions/comments and have a great time!

Delicious and Nutritious
The food we use to celebrate Thanksgiving is delicious and may also be nutritious. But if we stuff ourselves we are likely to suffer the consequences. What better time to study digestion, what we get from food, and how science comes to the rescue when we over do it?

Thanksgiving Science: Tryptophacts and Tryptophantasies
Is turkey what makes you sleepy at Thanksgiving? No. Maybe. (How much did you eat?)

Food and the Digestive System
This lesson focuses on the digestive system. Students identify the major organs of the digestive system and determine the function of each organ. This Science NetLinks lesson is the first of a three part series.

Good Food, Good Health
Students explore ways in which food provides energy and materials for our bodies. In this investigation, students will use online resources to help them explore how food can affect their overall health. This lesson is the second of a Science NetLinks three part series.

Got Broccoli?
This lesson is designed to help students understand why the body needs food, and how it takes necessary nutrients as food passes through the digestive system. Students are asked to look critically at the advertising claims of foods they eat, recognizing those that ascribe unrealistic, emotional, or psychological benefits to foods, rather than nutritional benefits. Students will then create an original advertising campaign for a “forgotten” vegetable, presenting compelling, factual information about the nutrients found in these foods and the benefits derived from them.

Enzyme Salad Lab
In this activity students examine the effects of a specific digestive enzyme (bromelin) found in pineapple on a specific protein found in Jell-O.

The Effectiveness of Antacids
In this performance assessment from PALS, students design and conduct a scientific experiment to test which of four antacids would be most effective for neutralizing acid. They will rank the antacids in order from most effective to least effective and explain how they determined the effectiveness of each one. The resource is designed to assess grades 9-12 students but can be modified to be appropriate for middle level students.

Pop-Up Turkey Thermometers
How do those pop-up thermometers they put in turkeys work? It turns out that there is a little piece of a solder type material in the thermometer that melts at 185 degree F. So when the turkey reaches that temperature the solder melts, the plastic pops up, and you know it is time to eat. This bit of Thanksgiving information can be related to change of phase, heat transfer, and physical/chemical change. You could also consider a design challenge around this idea.

Matter of State
This lesson is designed to give students the opportunity to observe a phenomenon created by particle movement. Students begin to move from the fundamental concept of solid, liquid and gas to the reasoning for why the states exist under given conditions.

The Heat Is On
In this resource students discover how heat is transferred by conduction through matter by watching interactive video segments.

Turkeys and Genetics
The turkeys served on Thanksgiving Day are dramatically different from the ones served many years ago. To meet the demand for birds with more white meat, turkeys have been selectively bred and fed special diets designed to result in birds with larger breasts. Consider engaging students in a discussion of this somewhat controversial practice as a way to introduce genetics.

Modeling Mendel’s Pea Experiment
This modeling activity allows students to discover for themselves what Mendel uncovered in his famous pea experiments. It is an excellent introduction to Mendelian genetics which generates discussion and stimulates interest in Mendel’s principles. Students are encouraged to use the same observation and critical thinking skills that Mendel used.

We Want Your Feedback
We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? We invite you to share with us and other readers by posting your comments. Please check back often for our newest posts or download the RSS feed for this blog. Let us know what you think and tell us how we can serve you better. We appreciate your feedback on all of our Middle School Portal 2 publications. You can also email us at msp@msteacher.org. Post updated 4/09/2012.