Names: Date:
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 “LD
50
” is the typical measure used to evaluate acute toxicity.
The LD
50
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 LD
50
values and then indicate which toxin is the most potent.
LD
50
Values for Various Chemicals
Substance
Water
Glucose
Sodium chloride
Caffeine
Sodium cyanide
Arsenic trioxide
Aflatoxin
(moldy legumes and grains)
Location for LD
50
information www.sigmaaldrich.com
MSDS sheet 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 www.msds.chem.ox.ac.uk
MSDS sheet
LD
50
(mg/kg)
LD
50
Oral rat =
LD
50
Oral rat =
LD
50
Oral rat =
LD
50
Oral rat =
LD
50
Oral rat =
LD
LD
50
50
Oral rat =
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 3 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.
Teratogens
Substances that cause developmental malformations (birth defects) are known as teratogens . The list of known or suspected teratogens is unfortunately very long and includes a variety of compounds, ranging from simple inorganic materials (e.g., cadmium and its salts, carbon monoxide) to common organic solvents (e.g., benzene, chloroform,
N,N-difromamide, toluene) to complex molecules of synthetic or biological origin (e.g.,
Librium, testosterone). One of the most famous teratogens is thalidomide.
5.
Visit www.sigmaaldrich.com
and indicate which enantiomer of Thalidomide is the potent teratogen.
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.

6.
In Experiments 2 (Bleach Oxidation of an Unknown Alcohol) and 4 (Synthesis of
Benzopinacol and Benzopinacolone), we work with acetic acid. This reagent is very corrosive and should be handled with care. Go to the MSDS sheet on www.sigmaaldrich.com
and provide the “Potential Health Effects” below.
7.
In Experiment 8 (Nitration of Methyl Benzoate), we work with nitric acid which is even more corrosive than acetic acid. Take a look at the MSDS sheet on www.sigmaaldrich.com
and provide the first aid instructions in case of “skin contact.”
Lachrymators
Some compounds are incredibly irritating to mucous membranes (eyes, nasal passages), and exposure to their vapors causes severe eye watering (lachrymation). Both solid and liquid compounds can display sufficiently high vapor pressure to act as lachrymators.
These compounds form the basis of “tear gas” agents.
Unstable compounds
Certain classes of compounds are shock sensitive and can explosively decompose.
Whereas some explosives require a primer to set them off, others known as primary explosives, do not need a primer and are thus particularly dangerous. Organic peroxides and inorganic perchlorate salts are notoriously explosive, and polynitrraated organic compounds (e.g. nitroglycerin, hexanitrohexaisowurtzitane) are also well-known for their explosive properties.
O
O
O
O
O
O
O
2
N
O O
NO
2
O
NO
2 cumene hydroperoxide dibenzoyl peroxide nitroglycerin