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How long should the skin or eyes be flushed with water in the event of a chemical exposure?

Most standard sources recommend that water rinsing/flushing following skin or eye contact with a chemical should continue for 15 or 20 minutes. However, all chemicals do not cause the same degree of effects (some are non-irritants while others can cause severe corrosive injury). At the present time, there is insufficient scientific evidence available to properly address the question of how long flushing should continue. However, it makes sense to tailor the duration of flushing to the known effects of the chemical or product, as follows:

  • 5-minutes for non-irritants or mild irritants,
  • 15-20 minutes for moderate to severe irritants and chemicals that cause acute toxicity if absorbed through the skin,
  • 30 minutes for most corrosives, and
  • 60 minutes for strong alkalis (e.g. sodium, potassium or calcium hydroxide).

It is very important that water flushing start immediately following skin or eye contact with a chemical. It is better if complete water flushing occurs on-site. However, moving the victim to an emergency care facility earlier may be necessary depending on the victim's condition (e.g. compromised airways, breathing or circulation) and/or the availability of a suitable water supply. If it is necessary to transport the victim before completing flushing on-site, flushing should continue during emergency transport, taking proper precautions to protect emergency services personnel.

Note that the manufacturer/supplier may also specify a cleansing agent (e.g. non-abrasive soap) if appropriate, or may recommend an alternative agent in exceptional cases if water is clearly inappropriate.

OSH Answers has more information on emergency eyewash and shower equipment.


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

In the past, emergency oxygen was commonly recommended as a first aid procedure for almost any chemical inhalation exposure. Later, concern was expressed that the administration of oxygen itself may be harmful if carried out improperly or in the wrong circumstances. In particular, there was concern that administering oxygen to victims with chronic obstructive lung diseases, such as chronic bronchitis or emphysema, could cause the victim to stop breathing. However, recent reviews have concluded that, during an emergency situation, the lack of oxygen is the most critical issue and there should be little concern over worsening the condition of victims with chronic obstructive pulmonary disease.

The presence of oxygen cylinders in the workplace can introduce additional hazards. For example, since oxygen supports combustion, the presence of oxygen cylinders could contribute to a fire hazard in the workplace. Also, since oxygen is stored under high pressure, the cylinder can behave like a missile if the valve breaks or the tank is punctured. Therefore, the risks and benefits of storing and maintaining an emergency oxygen supply in the workplace must be weighed.

There are some situations where the benefits of emergency oxygen outweigh the potential risks associated with maintaining and storing oxygen cylinders in the workplace. Emergency oxygen may be beneficial following exposure to chemicals that interfere with the body getting the necessary levels of oxygen to sustain life and health, including chemicals that:

  • Displace oxygen in the air, reducing the amount of oxygen available for breathing (e.g., helium, argon, methane, carbon dioxide or nitrogen).
  • Reduce the ability of blood to transport oxygen (e.g., carbon monoxide poisoning, or methemoglobinemia (presence of an oxidized form of hemoglobin in the blood that does not transport oxygen)).
  • Compromise the use of oxygen by body tissue, as with cyanide or hydrogen sulfide toxicity.
  • Interfere with the ability of oxygen to cross through the lungs to the blood stream, as occurs with pulmonary edema, a potentially fatal accumulation of fluid in the lungs. Ammonia, phosgene and chlorine are examples of chemicals that can cause pulmonary edema.
  • Provoke a severe asthma attack (e.g., toluene diisocyanate).

Additional training of first aid providers is required since basic first aid training courses do not include oxygen administration. First aid providers must be familiar with the laws that govern the use of oxygen administration in their workplace.


When should vomiting be induced following ingestion of a chemical?

Vomiting should NOT be induced following ingestion of a chemical in an occupational setting unless advised by a Poison Centre or doctor. Some of the arguments against inducing vomiting are:

  • The amount of chemical accidentally ingested by an adult is generally estimated to be very small (14-21 mL or about 0.5-0.75 oz).
  • 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.
  • There can be significant risks associated with inducing vomiting especially in emergency situations.
  • There does not seem to be a reliable and safe first aid procedure for inducing vomiting in adults.
  • Medical attention is usually available quite quickly in most situations.

In the event of a chemical ingestion, the best course of action is to call your local Poison Control Centre or a doctor and follow their advice. They will ask you specific questions, such as the name of the product ingested, the amount ingested and the condition of the victim. This information will assist them in determining the best course of action.


Should water or milk be given to dilute a chemical that has been ingested?

Much of what we know about the benefits of diluting an ingested chemical with water or milk is based on in vitro (test tube) and ex vivo (using harvested rat esophagi) studies.

Based on their evaluation of the evidence for dilution with milk or water, the American Heart Association and American Red Cross recommend that people should not take anything by mouth for an ingested poison unless specifically told to do so by a doctor or the poison control centre.


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.

Activated charcoal is sometimes considered to be an antidote. Activated charcoal works by binding the chemical in the stomach so it cannot be absorbed through the stomach. According to the American Academy of Clinical Toxicology and the European Association of Poisons Centres "the administration of activated charcoal may be considered if a patient has ingested a potentially toxic amount of a poison (which is known to be adsorbed to charcoal) up to 1 hour previously...". In general, the administration of activated charcoal is NOT considered a first aid procedure. Activated charcoal may be administered in the emergency department or under medical supervision.

Some chemical classes do have true antidotes - cyanides and organophosphate pesticides are good examples. You can determine which chemicals used in your workplace have antidotes by consulting with a doctor with certification in medical toxicology or occupational medicine, or the manufacturer/supplier of your product. These specialists can advise you on situations where it may be appropriate to store an antidote onsite. Special training of first aid providers will be required.


How do I know which first aid procedures to follow for chemicals used in my workplace?

In order to know what first aid procedures to follow, it is essential that you know what chemicals are present in your workplace. Consult your chemical inventory and the First Aid Measures Section on the Material Safety Data Sheets (MSDSs). Create a list of chemicals, their properties and their corresponding first aid requirements. Be sure that the emergency first aid providers in your workplace have the appropriate training and authority (if necessary) to deal with the types of chemicals used at your workplace.

Finally, make sure your local hospital is aware of any chemicals on your site that may require special first aid procedures, antidotes or medical follow-up.


Does CCOHS have more information on first aid for incidents involving chemical exposures?

CCOHS staff prepared the publication The Material Safety Data Sheet - A Practical Guide to First Aid as a source of information for people interested in developing or evaluating first aid recommendations for Material Safety Data Sheets. It is also useful for developing first aid programs for responding to chemical exposures in workplaces.

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Document last updated on July 4, 2012

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