A hazard is any biological, chemical, mechanical, or physical agent that is reasonably likely to cause harm or damage to humans, other organisms, or the environment in the absence of its control.[1] This can include, but is not limited to: asbestos, electricity, microbial pathogens, motor vehicles, nuclear power plants, pesticides, vaccines, and X-rays. Identification of hazards is the first step in performing a risk assessment and in some cases risk assessment may not even be necessary.
Contents |
A biological hazard is one originating from an organism that is foreign (in presence or concentration) to the organism being affected. Many biological hazards are associated with food, including certain viruses, parasites, fungi, bacteria, and plant and seafood toxins.[2] Pathogenic Campylobacter and Salmonella, are common foodborne biological hazards. The hazards from these bacteria can be avoided through risk mitigation steps such as proper handling, storing, and cooking of food.[3] Disease in humans can come from biological hazards in the form of infection by bacteria, viruses, or parasites. There is some concern that new technologies such as genetic engineering pose biological hazards. Genetically modified organisms are relatively new man-made biological hazards and many have yet to be fully characterized. For example, corn expressing insecticidal Cry proteins from the bacterium Bacillus thuringiensis was first introduced in 1996 and many of its potential detrimental effects on non-target organisms have yet to be examined.[4]
A chemical can be considered a hazard if by virtue of its intrinsic properties it can cause harm or danger to humans, property, or the environment.[5] Some chemicals occur naturally in certain geological formations, such as radon gas or arsenic. Other chemicals include products with commercial uses, such as agricultural and industrial chemicals, as well as products developed for home use. Pesticides, which are normally used to control unwanted insects and plants, may cause a variety of negative effects on non-target organisms. DDT can build up, or bioaccumulate, in birds resulting in thinner-than-normal egg shells which can break in the nest.[3] The organochlorine pesticide dieldrin has been linked to Parkinson’s disease.[6] Corrosive chemicals like sulfuric acid, which is found in car batteries and research laboratories can cause severe skin burns. Many other chemicals used in industrial and laboratory settings can cause respiratory, digestive, or nervous systems problems if they are inhaled, ingested, or absorbed through the skin. The negative effects of other chemicals, such as alcohol and nicotine, have been well documented. Hazards associated with chemicals are dependent on the dose or amount of the chemical. For example, iodine in the form of potassium iodate is used to produce iodised salt. When applied at a rate of 20 mg of potassium iodate per 1000 mg of table salt, the chemical is beneficial in preventing goiter, while iodine intakes of 1200–9500 mg in one dose have been known to cause death[7]
A mechanical hazard is any hazard involving a machine or process. Motor vehicles, aircraft, and air bags pose mechanical hazards. Compressed gases or liquids can also be considered a mechanical hazard.
A physical hazard is a naturally occurring process that has the potential to create loss or damage. Physical hazards include, but are not limited to, earthquakes, floods, and tornadoes. Physical hazards often have both human and natural elements. Flood problems can be affected by climate fluctuations and storm frequency, both natural elements, and by land drainage and building in a flood plain, human elements.[8] Another physical hazard, X-rays, are naturally occurring from solar radiation, but have been utilized by humans for medical purposes; however, overexposure can lead to cancer, skin burns, and tissue damage.[3]
The terms hazard and risk are often used interchangeably, however, in terms of risk assessment, these are two very distinct terms. As defined above, a hazard is any biological, chemical, mechanical, or physical agent that is reasonably likely to cause harm or damage to humans or the environment with sufficient exposure or dose.[1] Risk is defined as the probability that exposure to a hazard will lead to a negative consequence, or more simply, Risk = Hazard x Dose (Exposure).[3] Thus, a hazard poses no risk if there is not exposure to that hazard. Consider the following example:
Three people crossing the Atlantic in a rowboat face a hazard of drowning. (…) Three hundred people crossing the Atlantic in an ocean liner face the same hazard of drowning, (…). The risk to each individual per crossing is given by the probability of the occurrence of an accident in which he or she drowns. (…) Clearly the hazard [drowning] is the same for each individual, but the risk [probability of drowning] is greater for the individuals in the rowboat than in the ocean liner.[9]
Many mechanical hazards (aircraft, motor vehicles) and physical hazards (earthquakes, floods) have already been identified and well described. Hazard identification of new machines and/or industrial processes occurs at various stages in the design of the new machine or process. These hazard identification studies focus mainly on deviations from the intended use or design and the harm that may occur as a result of these deviations and are regulated by various agencies such as the Occupational Safety and Health Administration and the National Highway Traffic Safety Administration.[5]
Many biological hazards have also been identified. For example, the hazards of naturally-occurring bacteria such as Escherichia coli and Salmonella, are well known as disease causing pathogens and a variety of measures have been taken to limit human exposure to these microorganisms through food safety, good personal hygiene and education. However, the potential for new biological hazards exist through the discovery of new microorganisms and through the development of new genetically modified (GM) organisms. Use of new GM organisms is regulated by various governmental agencies. The U.S. Environmental Protection Agency (EPA) controls GM plants that produce or resist pesticides (i.e. Bt corn and Roundup ready crops). The U.S. Food and Drug Administration (FDA) regulates GM plants that will be used as food or for medicinal purposes.
A variety of chemical hazards (DDT, atrazine) have been described as well. However, every year companies produce more new chemicals to fill a new need or to take the place of an older, less effective chemical. Laws, such as the Federal Food, Drug, and Cosmetic Act and the Toxic Substances Control Act in the U.S, require protection to human health and the environment for any new chemical introduced. In the U.S., the EPA regulates new chemicals that may have environmental impacts (i.e. pesticides or chemicals released during a manufacturing process), while the FDA regulates new chemicals used in foods or as drugs. The potential hazards of these chemicals can be identified by performing a variety of tests prior to the authorization of usage. The amount of tests required and the extent to which they are tested varies depending on the desired usage of the chemical. Chemicals designed as new drugs must undergo more rigorous tests that those chemicals to be used as pesticides.