Names:
Date:
Experiment 1: Introduction to Chemical Hazards
Background:
In 1564, Paracelsus said that “Poison is in everything, and no thing is without poison.
The dose makes it either a poison or a remedy.” For example, table salt (NaCl) and
aspirin can be lethal if taken in sufficiently large dosage. In this experiment, we will
learn how hazardous materials are categorized and quantified for use in the assessment of
risk.
There are two general classes of hazards:
Acute chemical hazards are those which lead to immediate health consequences, while
the health implications of chronic chemical hazards are the result of cumulative
exposure. Hydrogen cyanide is considered an example of an acute chemical hazard and
has been used for capital punishment in the “gas chamber.” Nerve gases such as Sarin
and VX have been used for military operations. A single exposure to these compounds
can lead to immediate and dramatic health consequences, thus, they are known as acute
chemical hazards. A single exposure to mercury or lead compounds may or may not
result in observable health effects. It is typically the cumulative effects of longer-term
(chronic) exposure to such compounds that lead to serious problems.
1. Use the internet to identify the structures of Sarin and VX nerve gases and then
draw their structures with ChemDraw and paste them below.
Quantitative Evaluation of Chemical Hazards
Almonds contain measurable amounts of cyanide, gasoline contains cancer-causing
benzene, chemotherapy agents can themselves cause cancer. How do we know “how
hazardous” a compound is? In order to quantify the chemical hazards and evaluate the
possible risk of exposure (for example through physical contact, inhalation or ingestion),
we need to be able to evaluate the hazard.
Toxicity
The “lethal dose 50” or “LD50” is the typical measure used to evaluate acute toxicity.
The LD50 is usually provided in units of grams of substance per kilogram of body mass.
It represents the dosage of a compound that results in the death of 50% of an animal
population within one week of administration.
2. Fill in the LD50 values (Using the specified websites) and then indicate which
toxin is the most potent.
LD50 Values for Various Chemicals
Substance
Water
Glucose
Caffeine
Sodium
cyanide
Arsenic
trioxide
Location for LD50 information
www.sigmaaldrich.com
MSDS sheet
www.sigmaaldrich.com
MSDS sheet
www.sigmaaldrich.com
MSDS sheet
http://www.sciencelab.com/msd
sList.php
MSDS sheet
http://www.sciencelab.com/msd
sList.php
MSDS sheet
LD50 (mg/kg)
LD50 Oral rat =
LD50 Oral rat =
LD50 Oral rat =
LD50 Oral rat =
LD50 Oral rat =
Classes of Hazardous Substances
Hazardous chemicals can be classified according to the nature of their harmful effects in
humans. The following categories are distinguished by their mechanisms of action upon
chronic exposure or by the immediate results of acute exposure.
Carcinogens
If substantial evidence from epidemiological studies indicates that a substance causes
cancer in animals and/or humans, the substance is classified as a carcinogen. One of the
most common carcinogens is benzo[a]pyrene which is found in soot, cigarette smoke,
charred meat and diesel exhaust.
3. Use the internet to identify 2 additional carcinogens and then provide their
structures below using ChemDraw.
Mutagens
4. Provide a definition for mutagens.
Representative mutagens include 2-aminopurine, 5-bromouracil, hydroxylamine, and
ethyl methanesulfonate.
Flammables
Most organic solvents are flammable, however if we take precautions, they are not
difficult to work with. You will notice that the organic lab does not have natural gas.
We will use hot plates and heating mantles instead of Bunsen burners. Please be careful
not to spill organic solvents on these heating devices as there is still a risk that it could
catch fire.
5. In Experiment 2 (Recrystallization of Acetanilide), we work with ethyl acetate. This
compound is a standard organic solvent, however, it is highly flammable and
considered to be an irritant. Go to the MSDS sheet on www.sigmaaldrich.com and
provide the “Potential Health Effects” below.
6. In Experiment 7 (Dehydration of 2-Methylcyclohexanol), the 2-Methylcyclohexanol
is flammable and harmful if inhaled.
Go to the MSDS sheet on
www.sigmaaldrich.com and provide the “First Aid Measures” below.
7. In Experiment 9 (Nucleophilic Substitution: Preparation of Phenacetin), we work
with ethyl iodide. This is probably the most dangerous reagent you will work with
during the semester since it can attack the central nervous system. If you handle this
substance in the hood with gloves, you will be fine. Go to the MSDS sheet on
www.sigmaaldrich.com and provide the “Handling and Storage” information
below.
Corrosives
Such hazardous substances as strong acids and bases as well as compounds that form
acids or bases upon decomposition are considered corrosives. Care must be taken when
working with these compounds since they can cause severe skin and tissue damage.
8. In Experiment 8 (Diels-Alder Reaction of a-Phellandrene and Maleic Anhydride),
we work with maleic anhydride which is very corrosive and causes serious burns.
Take a look at the MSDS sheet on www.sigmaaldrich.com and provide the “First
Aid Measures” below.