Chemical hazard

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Occupational hazards
Physical Chemical Biological Psychosocial
Hierarchy of hazard controls
Elimination Substitution Engineering controls Administrative controls Personal protective equipment Prevention through design
Occupational hygiene
Occupational exposure limit Exposure assessment Workplace exposure monitoring
Study
Occupational toxicology Occupational epidemiology Workplace health surveillance
v t e

Chemical hazards are

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.^[3]

Types of chemical hazard

Routes of exposure

The most common exposure route to chemicals in the work environment is through inhalation.^[4] 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.^[5] If the air is contaminated in the workplace, more air exchange will lead to the inhalation of higher amounts of chemicals.^[6]

Chemicals may be ingested when food or drink is contaminated by unwashed hands or from clothing or poor handling practices.

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.[9] In some exposures, the chemical will be absorbed through the skin and will result in poisoning.^[9] The eyes have a strong sensitivity to chemicals, and are consequently an area of high concern for chemical exposure. Chemical exposure to the eyes results in irritation and may result in burns and vision loss.^[10]

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.^[11]

Symbols of chemical hazards

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:^[12]

• 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.^[13] 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.^[14]

Controlling chemical exposure

Elimination and substitution

Chemical exposure is estimated to have caused approximately 190,000 illnesses and 50,000 deaths of workers annually.^[15] 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.^[16]

Engineering controls

Although the elimination and the substitution of the 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 engineer 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 engineer controls is the enclosure or isolation of the process that creates the chemical hazard.^[16]

Administrative controls and safe work practices

If the process that creates the chemical hazard cannot be enclosed or isolated, the next best method is the implementation of administrative and work practices controls. This is the establishment of administrative and work practices that will reduce the amount of time and how often the workers will be exposed to the chemical hazard. An example of administrative and work practices controls is the establishment of work schedules in which workers have rotating job assignments. This will ensure that all workers have limited exposure to chemical hazards.^[16]

Personal protective equipment

Employers should provide personal protective equipment (PPE) to protect their workers from chemicals used within the workplace. The use of PPE prevents workers from being exposed to chemicals through the routes of exposure—inhalation, absorption through skin or eyes, ingestion, and injection. One example of how PPE usage can prevent chemical exposure concerns respirators. If workers wear respirators, they will prevent the exposure of chemicals through inhalation.^[16]

First aid

In case of an emergency, it is recommended to understand first aid procedures in order to minimize any damage. Different types of chemicals can cause a variety of damage. Most sources agree that it is best to rinse any contacted skin or eye with water immediately. Currently, there is insufficient evidence of how long the rinsing should be done, as the degree of impacts will vary for substances such as corrosive chemicals.

Transporting the affected person to a health care facility may be important, depending on condition. If the victim needs to be transported before the recommended flush time, then flushing should be done during the transportation process. Some chemical manufacturers may state the specific type of cleansing agent that is recommended.^[17]

Long-term risks

Cancers

This section is an excerpt from Carcinogen.[edit]

Common carcinogens; clockwise from top left: tobacco smoking, alcohol, asbestos, ultraviolet radiation

A

daughter cells. The damage accumulates over time. This is typically a multi-step process during which the regulatory mechanisms within the cell are gradually dismantled allowing for unchecked cellular division.^[19]

The specific mechanisms for carcinogenic activity is unique to each agent and cell type. Carcinogens can be broadly categorized, however, as activation-dependent and activation-independent which relate to the agent's ability to engage directly with DNA.

alkylating agents.^[21]

The time from exposure to a carcinogen to the development of cancer is known as the

latency period. For most solid tumors in humans the latency period is between 10 and 40 years depending on cancer type.^[22] For blood cancers, the latency period may be as short as two.^[22]

Due to prolonged latency periods identification of carcinogens can be challenging.

A number of organizations review and evaluate the cumulative scientific evidence regarding the potential carcinogenicity of specific substances. Foremost among these is the International Agency for Research on Cancer (IARC). IARC routinely publishes monographs in which specific substances are evaluated for their potential carcinogenicity to humans and subsequently categorized into one of four groupings: Group 1: Carcinogenic to humans, Group 2A: Probably carcinogenic to humans, Group 2B: Possibly carcinogenic to humans and Group 3: Not classifiable as to its carcinogenicity to humans.^[23] Other organizations that evaluate the carcinogenicity of substances include the National Toxicology Program of the US Public Health Service, NIOSH, the American Conference of Governmental Industrial Hygienists and others.^[24]

There are numerous sources of exposures to carcinogens including

aniline dyes and bladder cancer, asbestos and mesothelioma, polycyclic aromatic hydrocarbons and scrotal cancer

among chimney sweeps to name a few.

Workplace exposure to silica dust or asbestos is also associated with pulmonary heart disease. There is evidence that workplace exposure to lead, carbon disulphide, or phenoxy acids containing TCDD, as well as working in an environment where aluminium is being electrolytically produced, are associated with stroke.^[3]

Reproductive and developmental disorders

• Biocontainment – Physical containment of pathogenic organisms or agents in microbiology laboratories
• Biological agent – Pathogen that can be weaponized
• Biosafety level – Set of biocontainment precautions
• Chemical safety – Safety of activities involving chemicals
• Health hazard
   – Hazards that would affect the health of exposed persons.
• Hierarchy of hazard controls – System used in industry to eliminate or minimize exposure to hazards
• Occupational exposure banding – Process to assign chemicals into categories corresponding to permissible exposure concentrations
• Occupational hazard – Hazard experienced in the workplace
• Planetary protection – Prevention of interplanetary biological contamination
• Process safety – Discipline dealing with the study and management of fires, explosions and toxic gas clouds from hazardous materials in process plants.
• Public health – Promoting health through informed choices

References