“ Laboratory first Aid ”

·       How long should skin be rinsed in the event of accidental chemical exposure?

 The American National Standards Institute (ANSI) Standard for Emergency Eyewash and Shower Equipment (ANSI Z358.1-1998) recommends that the affected body part must be flushed immediately and thoroughly for at least 15 minutes using a large supply of clean fluid under low pressure. However, other references recommend a minimum 20-minute flushing period if the nature of the contaminant is not known.

·       How long should skin be rinsed in the event of accidental chemical exposure?

The flushing or rinsing time can be modified if the identity and properties of the chemical are known. For example, at least :
5-minutes flushing time for mild irritants,
  - 20 minutes for moderate to severe irritants,
  - 20 minutes for non-penetrating corrosives, and
  - 60 minutes for penetrating corrosives.
If irritation persists, repeat the flushing procedure.

·       Under what circumstances should oxygen be administered as a first aid measure?

There are, however, some situations for which the benefits of oxygen administration are unquestionable. These situations include chemical exposures that can:

Ø          Interfere with the ability of oxygen to cross through the lungs to the blood stream, as in pulmonary edema, a potentially fatal accumulation of fluid in the lungs. Ammonia, phosgene and chlorine are examples of chemicals that can cause pulmonary edema.

Ø          Reduce the ability of blood to transport oxygen, as in cases of severe anemia, carbon monoxide poisoning, or methemoglobinemia (presence of an oxidized form of hemoglobin in the blood that does not transport oxygen).

Ø          Compromise the use of oxygen by body tissue, as in cyanide or sulfide toxicity.

·       When should vomiting be induced following ingestion of a chemical?

Note that ingestion of any chemical is not likely to occur in the workplace
   Evidence and common sense indicate that inducing vomiting is not necessary in most situations where there has been an occupational chemical ingestion. Some of the arguments against inducing vomiting are:

o        There is no conclusive evidence that victims of chemical ingestion who do have their stomachs emptied have more successful outcomes than victims who do not.

o        There can be significant risks associated with inducing vomiting especially in emergency situations.

o        There does not seem to be a reliable and safe first aid procedure for inducing vomiting in adults.

o        Medical attention is usually available quite quickly in most situations.

·       How do I know which antidote to have available for the chemicals in my workplace?

It is a common misperception that antidotes are available for most chemical poisonings. True antidotes are the exception rather than the rule. Three commonly recommended antidotes are the "universal antidote", activated charcoal, and milk.

      The universal antidote : is a mixture of tannic acid, magnesium oxide and activated charcoal. To quote one source, "There is not one iota of objective, controlled or quantitative evidence in its testimony." In other words, it does not work "universally".

      Activated charcoal works by binding the chemical in the stomach so it cannot be absorbed through the stomach. It is necessary to swallow up to 10 times the weight of the ingested chemical to ensure success of the antidote. This amount would be difficult to estimate and even more difficult to ingest because of the gritty, unappealing texture and taste of activated charcoal. In addition, activated charcoal can interfere with some treatments a doctor may choose to use.

      Sometimes milk is recommended as an antidote. It is thought that milk will slow the absorption of some chemicals through the stomach. This is true in some cases, but milk can also speed up the absorption of fat soluble chemicals. Evaporated milk is low in fat and may be useful in some circumstances, especially ingestion of corrosives. However milk, even evaporated milk, is unlikely to be readily available in most workplaces.

     Dilution of an ingested chemical with a small amount of water (240-300 mL or about 8-10 oz.) is the recommended procedure for most chemical ingestions. For corrosives, dilution with a small amount of water (240-300 mL) followed by dilution with milk, if available, is the recommended procedure.

     Two chemical classes which have true antidotes are cyanides and organophosphate pesticides. Amyl nitrate is a cyanide antidote and atropine is an antidote for organophosphate pesticide poisoning. Administration of these antidotes may be considered a medical act in some jurisdictions. Appropriate training and delegation of authority should be obtained from a doctor.