Chemical hazard

Chemical hazards are hazards present in hazardous chemicals and hazardous materials. Exposure to certain chemicals can cause acute or long-term adverse health effects. Chemical hazards are usually classified separately from biological hazards (biohazards). Chemical hazards are classified into groups that include asphyxiants, corrosives, irritants, sensitizers, carcinogens, mutagens, teratogens, reactants, and flammables. In the workplace, exposure to chemical hazards is a type of occupational hazard. The use of personal protective equipment may substantially reduce the risk of adverse health effects from contact with hazardous materials.

Long-term exposure to chemical hazards such as silica dust, engine exhausts, tobacco smoke, and lead (among others) have been shown to increase risk of heart disease, stroke, and high blood pressure. Gas, vapour, mist, dust, fumes, and smoke can all be inhaled. Those with occupations involving physical work may inhale higher levels of chemicals if working in an area with contaminated air. This is because workers who do physical work will exchange over 10,000 litres of air over an 8-hour day, while workers who do not do physical work will exchange only 2,800 litres. If the air is contaminated in the workplace, more air exchange will lead to the inhalation of higher amounts of chemicals.

Chemicals may be ingested when food or drink is contaminated by unwashed hands or from clothing or poor handling practices. When ingestion of a chemical hazard occurs it comes from when those said chemicals are absorbed while in the digestive tract of the body. Ingestion only occurs when food or drink has contact with the toxic chemical. This can happen through direct or indirect ingestion. When food or drink is brought into an environment where harmful chemicals are unsealed there is the possibility of those chemical vapors or particles contaminating the food or the drink. A more direct form of chemical ingestion is the possibility of consuming the chemical directly. This rarely happens but, it is possible, that if there is little to no labeling on the chemical containers and if they are not secured properly an accident can occur which could lead to someone mistakenly assuming the chemical was something it was not.

thumb|[[Chemical burn|Chemical burns are one type of consequence of exposure to a chemical hazard]]

Chemical exposure to the skin is a common workplace injury and may also occur in domestic situations with chemicals such as bleach or drain-cleaners. The exposure of chemicals to the skin most often results in local irritation to the exposed area. In some exposures, the chemical will be absorbed through the skin and will result in poisoning.

Injection is an uncommon method of chemical exposure in the workplace. Chemicals can be injected into the skin when a worker is punctured by a sharp object, such as a needle. Chemical exposure through injection may result in the chemical entering directly into the bloodstream.

Symbols of chemical hazards

alt=Chemical Hazard Symbols|thumb|260x260px|[[GHS hazard pictograms]]

Hazard pictograms are a type of labeling system that alerts people at a glance that there are hazardous chemicals present. The symbols help identify whether the chemicals that are going to be in use may potentially cause physical harm, or harm to the environment. The 9 symbols are:

Explosive (exploding bomb)
Flammable (flame)
Oxidizing (flame above a circle)
Corrosive (corrosion of table and hand)
Acute toxicity (skull and crossbones)
Hazardous to environment (dead tree and fish)
Health hazard/hazardous to the ozone layer (exclamation mark)
Serious health hazard (cross on a human silhouette)
Gas under pressure (gas cylinder)

These pictographs are also subdivided into class and categories for each classification. The assignments for each chemical depends on their type and their severity. The standard set of 9 hazard pictograms was published and distributed as a regulatory requirement through the efforts of the United Nations via the Globally Harmonized System of Classification and Labelling of Chemicals.

Controlling chemical exposure

thumb|A video on how exposure sampling works during a health hazard evaluation

Elimination and substitution

Chemical exposure is estimated to have caused approximately 190,000 illnesses and 50,000 deaths of workers annually. There exists an unknown link between chemical exposure and subsequent illness or death. Therefore, the majority of these illnesses and deaths are thought to be caused by a lack of knowledge or awareness concerning the dangers of chemicals. The best method of controlling chemical exposure within the workplace is through the elimination or the substitution of all chemicals that are thought or known to cause illness or death.

Engineering controls

Although elimination and substitution of harmful chemicals is the best known method for controlling chemical exposure, there are other methods that can be implemented to diminish exposure. The implementation of engineering controls is an example of another method for controlling chemical exposures. When engineering controls are implemented, there is a physical change made to the work environment that will eliminate or reduce the risk to chemical exposure. An example of engineering controls is the enclosure or isolation of the process that creates the chemical hazard.

Long-term risks

Cancers

Cardiovascular disease

A 2017 SBU report found evidence that workplace exposure to silica dust, engine exhaust or welding fumes is associated with heart disease. Associations exist for exposure to arsenic, benzopyrenes, lead, dynamite, carbon disulfide, carbon monoxide, metalworking fluids and occupational exposure to tobacco smoke. Any contact with harmful chemicals during the first few months of pregnancy or even after has been connected to some miscarriages and has affected the menstrual cycle to the point that it has been able to block ovulation. Chemicals inducing health issues during pregnancy may also affect infants or fetuses.