Assessing Exposure to Toxic Chemicals: General Chemistry Applied to Human and Environmental Health

Timothy E. Elgren, Professor of Chemistry
Myriam L. Cotten
, Associate Professor of Chemistry
Charles J. Borton
, Chemistry Laboratory Instructor
Gregory S. Rahn
, Chemical Instrumentation Specialist
Department of Chemistry, Hamilton College, Clinton, NY 13323

SENCER Model Course Logo

A one-semester Advanced General Chemistry course with a laboratory component has been developed that explores exposure to toxic chemicals. Through readings and guest lectures, students are introduced to health risks associated with chemical exposure to carcinogens and endocrine disruptors and sources of exposure. A set of laboratory projects were employed to provide students with a fundamental background in polymer chemistry, analytical methodologies and strategies for chemical separations. These projects led to an analytical assessment of our limits of chemical detection of bisphenol A (BPA) and a number of halogenated flame retardants (HFR). BPA is a component of many hard plastics (polycarbonates) and included in many of the resins that coat the inside of aluminum cans. Chemical flame retardants have become ubiquitously incorporated into foams used for carpet backing and furniture. Many are the same compounds previously banned from use as flame retardants in children’s pajamas due to their known toxicity. Students were asked to craft a five-week project in which they probed the leaching of BPA from plastics or the presence of HFR in foam. All students presented posters at a public poster session to educate our campus on the nature of these toxic compounds and potential exposures. Some examples of student projects are listed below:

“Fire Retardants in Baby Products”
“Effect of EtOH on Leaching of BPA”
“The Effect of Phosphate, Amino Acids, and pH on the Leaching of BPA”
“Assessing Exposure to BPA from Polycarbonate Cups”
“Plastic Lining in Aluminum Cans Leach BPA”
“Baby Bottles and BPA”

Through lectures, investigative laboratory experiences, and non-technical reading assignments, we have tried to introduce current issues of general public interest that are chemical in nature. The strategy is to build context and interest before exploring the chemical principles in greater depth.

Small class sections allow for extended discussions. Each section met three times per week (MWF) for an hour. An additional one-hour class period was scheduled weekly (Mondays at noon) for both sections to meet together. This time was used for speakers, discussions, laboratory instruction, and exam review.

The progression of laboratory experiences was designed to 1) demonstrate that plastics are not inert materials, 2) introduce analytical methodologies including assessment of limits of detection, 3) introduce separation methods that can be used to extract toxic chemicals from polymers, and 4) provide basic training on instruments to be used for analytical determinations. This progression prepares students with little laboratory experience for the open-ended research question that they are asked to propose which must focus on some aspect of detecting bisphenol-A or halogenated flame retardants.

Linking Science and Social Issues

Chemical basis of plastics (polymers, bonding, solubility): Taught through sources of human exposure to toxic chemicals including known endocrine disruptors such as bisphenol A and terephthalates.

Analytical and instrumental measurements (error analysis, spectroscopy, use of analytical glassware and balances, chromatography): Taught through acceptable levels of exposure and demonstrated with measurement of cocaine contamination of dollar bills.

Chemical separations (acid/base chemistry, solvent polarity, solubility, chromatography): Taught through examination of mobilization of various chemical toxins based on solubility.

Modes of chemical exposure (solubility, pH, acid/base chemistry, aqueous chemistry, structure and bonding): Taught through a mock Legislative Action Committee reviewing the proposed use of a potent pesticide to combat a local infestation.

Scientific integrity and ethics (scientific method, peer review): Taught through examination of various scientific issues currently in the public domain, including tobacco regulation, global climate change, and human cloning.

The Course

Syllabus Chemistry 125
Laboratory-Iron in Solution

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Laboratory-Caffeine Extract

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Laboratory-Cocaine

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Laboratory Assignments

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Writing Assignment

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Grading

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Course Design

Format (seminar, lecture, labs, texts used etc)

  • Small class size (16 per seminar and lab section)
  • Lectures used to cover basic chemical content.
  • Lab used to prepare students to explore analytical measurements.
  • Textbook used as a resource book.
  • Various readings incorporated to explore issues beyond the chemical content, including Our Stolen Future by T. Colborn, D. Dumanoski, J. P Myers, Doubt is Their Product: How Industry’s Assault on Science Threatens Your Health, D. Michaels, Slow Death by Rubber Duck: The Secret Danger of Everyday Things, R. Smith, B. Lourie.
  • Speakers invited to help introduce context for studying toxic chemicals, such as Dr. Arlene Blum “Chemical Flame Retardants”.

Evaluating Learning

Student Evaluation (Graded assignments, exams, projects)

  • Three exams
  • Two writing assignments (“What’s known about the risks associated with bisphenol A?”, “A case for or against the local use of thifene”)
  • Laboratory evaluation (Appendix VIII)

Course Evaluation
The SALG-Instrument (http://www.salgsite.org/) was modified for assessment of this course. Student answers to assessment questions allowed us to gauge the impact of the course and laboratory. Based upon their responses, the course activities that had the greatest impact on their learning in the course are listed below:

  • Unstructured laboratory projects
  • How studying this subject area helps people address real world issues
  • Role that the general population plays in protecting human and environmental health
  • Connection between Science and Public Policy

Background and Context

  1. Course history. Chemistry 125 is a one-semester General Chemistry course for our more advanced students. We also teach Chemistry 120, which is also a one-semester introduction to chemistry. Previously, both courses (120 and 125) used the same laboratory experiments. This new lab structure is designed to challenge these students with open-ended research-like experiences done in the context of an issue of public interest. The course has grown to include more discussion of these issues to provide greater background for the laboratory experience.
  2. Role of the course in the undergraduate curriculum of your institution. This is one of the two options for taking General Chemistry.
  3. Internal and external funding Sources. 2008 Christian A. Johnson Teaching Enhancement Award (Internal award to T. Elgren), Sherman Fairchild Award to support instrumentation for analytical chemistry.

Related Resources

VI. Resulting Projects and Research (Presentations, articles, recognition)

  • J. Litzky, W. McIvor, M. Cotten, C. Borton, G. Rahn, T. Elgren “Chemical Toxins: Exposure to Bisphenol A and Halogenated Flame Retardants”, poster presented at the
    2010 Washington Symposium and Capitol Hill Poster Session, National Center for Science & Civic Engagement.
  • T. Elgren “Integrating Applied Learning: Forging Direct Links to the Curriculum”, invited Keynote Address at the Conf. on Applied Learning in Higher Education, Missouri Western State Univ.: St. Joseph, MO Feb 2009.