Commonly Used Chemicals Can Be Dangerous
"I have smelled cyanide gas in more than one classroom," noted Richard C. Clark, science specialist for the Minnesota Department of Education, organizer of Chemical Safety Day.
"When I taught high-school science in Detroit, our offices were in chemical storerooms," commented John A. Novak, now a professor of science education at Ohio State University.
"Just the other week I found sodium, oodles of it, in an unlabeled, deteriorating can in a cabinet where students keep their lab supplies," added Marcelline A. Barron, a science teacher in Cincinnati, one of the few school systems around the country that has completed a districtwide cleanup operation.
Such comments are typical of those made in interviews with school officials about the problem of hazardous chemicals in school laboratories.
The following hazardous chemicals were among those disposed of by Minnesota schools at the suburban St. Paul "drop site" on Nov. 12. Education Week asked chemical-safety consultant Jay A. Young of Silver Spring, Md., to comment on the danger posed by each of the chemicals, which, he says, are commonly found in school laboratories around the country.
With the exception of sodium, sodium nitrate, and benzene (all of which, Mr. Young says, must be used with appropriate precautions), there is no legitimate reason for having these substances in school laboratories:
Picric Acid--When it contains less than 14 percent water, it will explode when given a shock--such as being knocked from a shelf or struck with a lab instrument. It should be assumed, if picric acid is old, that it does not contain enough water. One should not risk opening a container to find out.
Potassium Cyanide--As with all other cyanides, its principal hazard is toxicity. It is very poisonous, and should be used with caution so as to avoid ingestion or exposure through cuts or abrasions. When mixed with other acids, it generally forms hydrogen cyanide, a very toxic gas.
Sodium--It is a reactive metal. If, while stored, it comes in contact with water, a severe explosion could result. It is also air-reactive. If the petroleum product--usually kerosene--that is stored with it evaporates, it may ignite if exposed to air.
Carbon tetrachloride--It is a toxic liquid considered by some to be carcinogenic to humans. The breathing of carbon tetrachloride vapors may cause later problems with liver function.
Carbon disulfide--It is probably more poisonous than carbon tetrachloride, although it is not a suspected carcinogen. It is also extremely flammable. It will ignite spontaneously if warm.
Sodium Nitrate--This chemical is moderately toxic, as are all nitrates, and is an oxidizer. If it is mixed with substances that burn, a violent reaction may take place.
Potassium dichromate--This is also an oxidizer. And it is toxic. If it is inhaled or enters the body through a cut, it will probably not be fatal, but could damage the kidneys or liver. Also, dichromates and chromates in general are often used in reactions that produce suspected carcinogen products.
Benzidine--It is a known carcinogen.
Hydrofluoric Acid--Unlike most acids, it does not cause immediate pain when it comes into contact with the skin. Rather, it becomes excruci6atingly painful several hours after exposure. Treatment, which should be initiated immediately, includes flushing the exposed area with water, removing contaminated clothing, and immersing the affected body parts into ice-cold 70-percent-alcohol solution (with crushed ice), to be continued at one- to four-hour intervals.
Arsenic Trioxide--It is extremely toxic, and is a human carcinogen.
Benzene--It is a carcinogen. The usual exposure results from breathing benzene vapor.
Mr. Young also characterized the hazards of the following chemicals. These were found in Minnesota school laboratories but, due to their explosive nature, were not accepted by the University of Minnesota at the dump site on Nov. 12:
Ethyl ether, dioxane, tetrahydrofural, other ether compounds--All of these chemicals have a tendency to produce ether peroxides if left to stand in storage for long periods of time. Ether peroxides are white, waxy solids, which explode when "touched with a feather." And they explode violently: One small piece the size of a bread crumb can blow a hole through the middle of the human body.
Ethers should be stored for short periods of time only, and destroyed before the expiration date on package labels.
If they are stored for longer periods or if the manufacturer has not supplied an expiration date, the conservative position is to assume the container has ether peroxides, whether or not the container has been opened. In such cases, the safest removal procedures require the use of a remote-controlled robot device so that no human being is directly exposed to the possibility of explosion.