TOXIC BOTTLES? CHAPTER 3 INFORMATION LITERACY 1 CHAPTER 3 INFORMATION LITERACY TOXIC BOTTLES? On the trail of chemicals in our everyday lives

Do Now 1. Obtain a copy of “But It’s Just a Bottle of Water…” 2. Read Part I. 3. Answer the question on page 2. (please be specific) 4. Share your answer with a neighbor. 5. Share your answer with the class. 3/27/12

Toxins are chemicals that cause direct damage upon exposure. Toxins fall into two categories, natural and synthetic.

NATURAL TOXINS ARE NOT ALWAYS SAFE. Arsenic, a basic element, can cause cancer and nervous system damage in humans.

Synthetic toxins are a problem because many are persistent chemicals—they don’t readily degrade over time.

According to the EPA: More than 80,000 chemicals are used in the United States 1,000-2,000 new chemicals enter the market each year

Regulation of toxins begins with risk assessment—a careful weighing of the risks and benefits associated with any given chemical.

Federal agencies (FDA, EPA) are mandated with protecting us from harmful chemicals. They can heavily regulate or ban those deemed dangerous.

In 2008, the National Toxicology Program (NTP) analyzed studies about Bisphenol A, or BPA, which is used in metal food cans and many plastic products.

NTP stated it had “some concern” about the effects of BPA exposure on brain, behavior, and prostate glands in fetuses, infants, and children.

1111 Canada and the European Union had recently banned the use of BPA in baby bottles and baby food cans.

1212 Most NTP panelists felt the data were too uncertain to warrant a ban, but they applied the precautionary principle, saying it would be prudent for industries to look for a BPA replacement.

Toxicologists create a dose-response curve to track the effects of a dose of a chemical, such as BPA.

Toxicologists use this curve to calculate the LD50 (lethal dose 50%), the dose that would kill 50% of the population.

The lower the LD50, the more toxic the substance The lower the LD50, the more toxic the substance. In this example, Substance A is the more toxic substance.

What is the LD50 of Substance B? 1616 Clicker Question What is the LD50 of Substance B? 10 ppm 31ppm 17ppm 7ppm Answer: C

Which substance is most toxic? 1717 Clicker Question Which substance is most toxic? Substance A Substance B Substances A & B are equally as toxic Answer: A

BPA is an endocrine disruptor: It mimics a hormone or prevents a hormone from having an effect

Endocrine disruptors have different effects at low and high doses, so dose-response curves and LD50s are trickier to calculate—and a “safe dose” is harder to determine.

As scientists debated the safety of BPA, and regulatory agencies struggled, people were left to decide whether they should purge BPA from their lives.

We can use critical thinking skills to analyze reports on potential toxins and help us determine what steps we should take to be safe.

To make decisions, we need to know whether a chemical has the potential to harm us and how great that harm might be.

First, we need to evaluate the source of the information about the chemical.

Next, we need to look for logical fallacies in arguments or claims about the chemical, so we won’t be misled.

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Be skeptical. Require evidence before accepting a claim as reasonable.

Evaluate the evidence: 2828 Evaluate the evidence: Is the claim from actual scientific studies? How relevant are the studies? Did the researchers look at human populations?

Be open-minded. Identify your own biases or pre-conceived notions and follow the evidence where it takes you.

Watch out for biases: Is the author promoting a specific position? Are they financially tied to a specific conclusion? Are they trying to support a predetermined conclusion?

There are rarely easy answers and science is never as straightforward as we would like it to be.

We are constantly uncovering new information and as our understanding grows, existing information often becomes obsolete.

Science is incremental: Each study is a piece of the puzzle. 3333 Science is incremental: Each study is a piece of the puzzle.

“Sometimes, if there’s enough momentum from the public, regulatory change will follow. But more often than not, because of the way the system works, it really has to start with individual consumers deciding for themselves that they won’t purchase or use certain items.” --Sarah Vogel