Unit 4 Honors Project

Thank you to everyone for being so patient to learn more about the Honors project.  We now have confirmation that we will actually be able to offer Honors credit for second semester.  Without further ado, here are the details for the Unit 4 Honors Project:

1. Read about the Flint, Michigan water crisis caused by lead-contaminated drinking water.  This article will serve as background knowledge to one of the many public health emergencies caused involving chemistry.
2. Research another human-caused environmental / public health crisis caused by toxic chemicals.
   • National Geographic is a good starting point to learn about existing Superfund sites in the United States.
   • At the bottom of the NatGeo article is a link to the Environmental Protection Agency (EPA) Superfund Site Database.
   • Search the database for a site that is meaningful to you.  For example, I scrolled down to the “Where You Live Map” and looked for Superfund sites near places I have lived.
3. Select one Superfund site and research how contamination from the site has affected the surrounding community.
   • What human activities led to contamination of the site?
   • What toxic chemical(s) are found at the site?
   • How many people live near the site?
   • How has the community changed as a result of the site?
   • How has the surrounding ecosystem changed as a result of the site?
4. Calculate the toxicity of chemicals at the site.
   • Use the PubChem database to research the LD₅₀ values for the toxic chemicals found at the site and rank order them from most toxic to least toxic (lowest LD₅₀ to highest LD₅₀).  Note: to compare LD₅₀ values, go to the Acute Effects section for each chemical and look for comparable data across the compounds you are researching. Not all chemicals have that section – be persistent!  If you need help, please ask!  Here are examples of the Acute Effects sections for the toxic chemicals dioxin and benzene.  Ideally, both chemicals would have toxicity data for humans (the most relevant organism for this project) with the same test type and route.  However, that is often not available so we move on to the next best data.  For example, both of these compounds have entries for rat / LD50 / oral which means toxicity studies were conducted by feeding these compounds to rats in increasing amounts until 50% of the rats died.  For dioxin, the rat oral LD₅₀ is 20 ug/kg and for benzene the rat oral LD₅₀ is 930 mg/kg.  What does this mean?  For starters, ug is the abbreviation for microgram (μg) and mg is the abbreviation for milligram.  There are 1,000 mg in 1 gram.  There are 1,000,000 μg in 1 gram.  Therefore, there are 1,000 μg in 1 mg.  This means it takes far less dioxin (by mass) to kill 50% of rats than it does benzene.  Therefore, by mass, dioxin is the more toxic of the two compounds.
   • But wait!  To truly compare toxicity, we need to account for the molar mass of each molecule.  Thankfully, PubChem has that information.  It’s actually the very first entry in the Chemical and Physical Properties section.  Sticking with our examples, the molecular weight of dioxin is 322 g/mol and and benzene is 78.11 g/mol.  Using dimensional analysis, we can convert the LD₅₀ in μg/kg or mg/kg to mol/kg.  Once we have the mol/kg values for both dioxin and benzene, we can conclusively say which one is the most toxic.
5. Focusing on the most toxic chemical (lowest LD₅₀ in mol/kg) at the Superfund site you selected, research the biology behind how the toxin affects humans at the level of the overall body, at the body system level, effects on specific organs, and specific effects on cells.  Be thorough in your research.  It is very possible that the information available is limited.  Include what you can and explain what you tried to find but could not. For example, if you could not find any information about the toxin affects specific organs, write “Effects of this molecule on specific organs are unknown at this time.”
6. Explanation of treatments (existing and in development) and how they work.  Again, be thorough in your research and clearly explain what you could find and what you could not find.  It is OK not to find a treatment – there simply might not be one yet.
7. Finally, what is the current status of your Superfund site?  What has been done to clean up the site?  Is it still actively being worked on or is it considered Ready for Anticipated Use?

Projects are due Sunday, May 31, 2020 by 11:59 PM.  The project deliverable is a Google Slides shared with me.  Include visuals (a map of the site location, images of the site if available, images and links from primary data sources, and images of all calculations must be included)!  Please ask questions as you have them.  Do not wait until the end of May to start this project.  Chip away at it each week and know that we will cover molar mass and LD₅₀ calculations during Weeks 33 and 34 as a class.

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