Toxicological concepts essay Example

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Toxicological Concepts Essay

Table of Contents

Section 1: Selected Scenario- Asbestos Removal (See Table Below) 3

Toxicology of Hazards in Asbestos Removal in Construction Industry 4

Asbestos fibers 4

Smoked asbestos 7

Dust Particles 8

Asbestos Dust Particulate Matter 13

Section 1: Selected Scenario- Asbestos Removal (See Table Below)

Hazard type

Entrance Route

Nature of Exposure

Asbestos fibers (fibrous silicate materials: Chrysotile fibers, Crocidolite fibers, and Amosite compounds

Fibrous silicate materials that come in the form of tiny fibers. They were initially mined and manufactured.

Through inhalation or breathing

Intermittent or continuous

Smoking (cigarette smoking increases risk of exposure of harmful asbestos fibers. Smokers are 10x riskier than the non-smokers

small quantities of asbestos fibers inhaled during smoking as those asbestos fibers are always present in the air

Airborne, inhalation or simply, through breathing (mostly through the nose)

Continuous exposure

Dust particles from mining, grinding or construction, occasional use of vermiculite

Small dust particles or the thin dust particles available in the air. Inhalable/inspirable dust, crystalline silica, and inhalable dust

Airborne, inhalation or simply, through breathing (mostly through the nose). Also, through the eyes and ears.

frequency of exposure, sometimes intermittently as the victim gets exposed

Tremolite and anthophyllite fibers of asbestos

Fibrous silicate materials that come in the form of tiny fibers.

The fibrous silicate materials enter the human body though inhalation or breathing because they are found in the thin air.

amount and frequency of exposure either intermittently or continuously

Noise pollution

Through grinding, breaking or other activities of mining, manufacturing or construction

Through hearing or through the ear

amount and frequency of exposure either intermittently or continuously

Toxicology of Hazards in Asbestos Removal in Construction Industry

Asbestos fibers— Asbestos fibers are tiny particles found the atmosphere but regardless of their tiny nature, these particles are visible from the naked human eyes (NSW Government, 2017). The fibers have various properties, differ in their toxicological content and have varied degrees of health effects on the individuals upon exposure (NSW Government, 2017). Apparently, there are five main categories of asbestos fibers based on a number of scientific sources reviewed by this report. The five common types of asbestos fibers are the Chrysotile fibers, Amosite fibers, Crocidolite fibers and the Tremolite and Anthophyllite fibers (NSW Government, 2017). To understand the toxicological nature of these fibers and the health implications they may have on individuals exposed to them, it is important to distinguish the chemical and physical impacts that each of the asbestos fibers can cause.

Chrysotile fibers are the most common forms of asbestos that are frequently found on the roofs, walls, floors and ceilings of residential and business buildings (NSW Government, 2017). Chrysotile fibers may have a serious health impact if accidentally inhaled. According to Neira (2014, p. 2), a World Health Organization’s official in Geneva, “exposure to asbestos occurs through inhalation of fibers primarily from contaminated air in the working environment, as well as from ambient air in the vicinity of point sources or indoor air in housing and buildings containing friable asbestos materials.” Although it is the most common type of asbestos fiber, studies have revealed that it takes more exposure to Chrysotile than the other types of asbestos fibers for someone to develop related diseases (NSW Government, 2017). However, scientists have postulated that a significant exposure to this kind of asbestos fiber has the possibility of exposing individuals to risks of developing lung, laryngeal, malignant mesotheliomas, and ovarian cancers.

The second category of asbestos fiber is the Crocidolite fibers. In terms of properties, the fiber contains serpentine and amphibole minerals. The Crocidolite fiber is normally yellow or dark gray in color and sometimes it appears blue when exposed to high soda content along the traces of magnesium and iron. It is normally considered a hazardous element within the construction industry because it is used as a spray on insulation, pipe insulation or in yarn and rope lagging. It is believed that the fibers of Crocidolite are most dangerous and lethal fiber because of its long, sharp and needle-like shape that is suspected to be very harmful when inhaled. When inhaled, the fibers are likely to concentrate in the body and cause gastrointestinal and larynx cancer, pleural and peritoneal mesotheliomas. Monograms have shown that mesothelioma is likely to occur in individuals living in surrounding where factories or construction activities involving Crocidolite are common.

The third and second most harmful asbestos fiber is the Amosite fiber. Amosite fiber is best known as the brown asbestos due to its color appearance (NSW Government, 2017). It is believed that the brown asbestos or Amosite originated from Africa and is currently a major component in the cement, which is an essential element in the construction industry. Amosite is also common in pipe insulations, insulation boards, ceiling tiles, and other thermal insulation products used in the construction industry. Once inhaled, the Amosite fibers are capable of causing serious damages to the larynx, the intestines and the lungs (NSW Government, 2017). It is believed that Amosite is the second most deadly asbestos fiber because it comprises of elements that attach themselves to the lungs, larynx and the intestines, after which they cause tumors and inflammations on the affected parts. These tumors later become cancerous and predispose individuals to cancer situations.

The fourth fiber that scientists have considered dangerous to the human health is the Tremolite fiber. Even though it is uncommon among the asbestos considered dangerous to the human health, the fiber has significant health implications when inhaled through the thin air. Tremolite is an amphibole fiber that manufactures have used it to produce construction material because, just like the other asbestos fibers, it is flexible in nature, resistant to heat and extreme weather, and can be woven and spun into clothes. As stated by Antero, Cantor, Attfield and Demers (2012, p. 220), “Amosite is a double chain silicate; brittle fibers; resistance to acids: none; occurs in asbestiform and non-asbestiform habit; iron-substituted derivative of Tremolite; common contaminant in Amosite deposit.” More often, Tremolite fiber may occur in large deposits of the nature of Chrysotile, vermiculite, and talc. Once its particles are inhaled, the victim may be at risk of developing gastrointestinal cancer, pleural thickening in a disease known as asbestosis and progressive fibrosis in the lungs.

The fifth asbestos fiber that has been linked to occupational hazards is Anthophyllite asbestos fiber. This type of asbestos compound is mined mainly in Finland, where it originates (Neira, 2014). It has a gray-brown color and was thought to have been commercially available for composite flooring (Neira, 2014). In a test of the impact of Anthophyllite in its natural state of combining with other asbestos as a contaminant, researchers found that lung cancer is elevated in both the smokers and the non-smokers (Neira, 2014). This kind of asbestos is harmful and can contributed greatly in exposing people to risks of developing both laryngeal and lung cancers, as well as Mesotheliomas (Neira, 2014). In an experiment on animals, Neira (2014, p.26) revealed that after “intra-pleural or intra-peritoneal injection of Chrysotile, mesotheliomas induction was consistently observed in rats, when samples contained a sufficient number of fibers, with a fiber length of greater than 5μm.”

Smoked asbestos— in construction, involvement with asbestos may occur when people engage in direct mining of asbestos, milling of asbestos, repair, alteration or demolition of a building or even other structures containing asbestos, or constructing a house using materials that have asbestos (Neira, 2014). Getting contact with asbestos does not have any clemency and even those not involved the construction or use of material with asbestos are at risk of being affected by it (Neira, 2014). However, smokers are often at greater risks of inhaling poisonous asbestos because smokers attract the particles on the cigarettes and sometimes they are used to clinging on the lung carcinoma, which is a part that is most prone to cancer. More often smokers are at risk of developing lung cancer because of the nature of smoking and frequency of exposure. As Antero, Cantor, Attfield and Demers (2012, p. 291) postulate, “the inhalation of tobacco smoke as well as mineral fibers is associated with excess generation of reactive oxygen and nitrogen metabolites, cell injury and apoptosis, and persistent lung inflammation.”

In the human body, excess production of oxidants has been said to associate with the enhancement of the penetration of the harmful asbestos fibers into the epithelial cells of the respiratory system (Neira, 2014). This process often impairs fiber clearance and reduces the possibility of the body to fight the manifestation and concentration of fiber. The presence of asbestos in the lungs also alters with the ability of the lungs to manage the regular metabolism and detoxification of the inhaled tobacco smoke carcinogens. In another way, as Antero, Cantor, Attfield and Demers (2014, p.291) postulates, “asbestos fibers can also adsorb tobacco smoke carcinogens and metals and facilitate their transport into the lungs.” Smoking in asbestos manifested areas is also harmful because asbestos fibers have been shown to take part in the activation of cell-signaling pathways and growth-factors receptors, which are responsible for stimulating cell proliferation and supporting the survival of cancer-causing cells that cause tumors and inflammations.

In a summarized view of how the smoking of tobacco highly associates with increased likelihood of cancer related to asbestos, Neira (2014) produced a very interesting summation of the whole idea. According to Neira (2014, p. 291), co-exposures to tobacco smoke and mineral fibers can amplify acquired genetic mutations induced by tobacco smoke carcinogens, and amplify cell proliferation in response to tissue injury, leading to an increased risk for the development of lung or laryngeal cancer. In a research conducted on the construction premises and mainly one that involves constructors and build engineers who smoke, Neira (2014) discovered that several instances of lung cancer and laryngeal cancer associated with the constructors and those involved in the construction industry are those in which the contractors are smokers of cigarette. Abrasive blasting of constructed structures, earth-moving, excavation, concrete work, masonry, highway and tunnel construction while smoking, are some of the risk-predisposing activities in construction.

Dust Particles— Asbestos dust particles may not necessarily cause cancer or severe impairments associated with the sharp-pointed fibers. Sometimes a mild exposure to asbestos dust may result some kind of a kind known as the diffuse pleural thickening or pneumonia of the thorax. The third most common form of infection arising from an exposure to asbestos is the asbestosis condition. Asbestosis condition is not largely associated with the tiny fibers that cause laryngeal and lung cancers, it is the dust particles that cause progressive fibrosis of the lungs with varies degree of severity. The practices are tiny and vary in color depending of the fiber associated or depending on the composure of the material producing asbestos. More often, this dust can result in the formation of bilateral fibrosis or brushing of the lungs, commonly known as homecoming of the lungs. A person exposed to such a situation often tends to produce a persistent cough, with blood in the spectrum, experience difficulty in swallowing, swelling of the neck, shortness of breath, hoarseness or produce a wheezing sound.

Noise— dealing with asbestos presents the danger of experiencing health implications associated with noise pollution. More frequently, noise is produced when carrying out an abrasive demolition of the structures, constructing sections of the buildings, earthmoving, excavation, concrete work or highway and tunnel construction, causes noise that often results in considerable harm of those living around the environment where these construction activities are ongoing. Noise pollution, if very much consistent and the victims are exposed regularly, can often predispose the affected individuals to hypertension, hearing impairments, or even ischemic heart disorders. Debris consisting asbestos compounds, together with regular noise from the construction sites, can cause double health crises to those exposed to construction sites where asbestos pollution and noise are widespread. With estimates showing that over 400 death incidences in the U.S are currently attributed to non-occupational exposure to asbestos, construction sites can be more dangerous.

Exposure standards and sampling methods

Standards for Asbestos Fibers

In dealing with exposure to harmful asbestos fibers, the world has come up with certain exposure standards that organizations must ensure that to some extent human beings are protected from unnecessary and excess exposure to these elements (OSHA, 2012). Occupational Safety and Health Administration (OSHA) is a branch of the federal government of the United States that is responsible for overseeing the safety issues of workers in organization and implementing safety regulations that are necessary for promoting safe working conditions for sustainable health in organizations (OSHA, 2012). OSHA also sets safety and health standards necessary for assisting organizations to limit human hazards in organizations in almost everywhere across the world, including Australia. Concerning asbestos exposure, OSHA has established three standards for asbestos exposure depending on the nature of the workplace. It has standards for general industry shipyard and construction (OSHA, 2012). Our focus in this realm is the standards set for the construction industry.

In order to limit asbestos exposure in the construction industry, OSHA has section 29 CFR 1926.110 of the OSHA standards that covers a number of construction activities suspected to predispose workers to asbestos inhalation (OSHA, 2012).. In section 29 CFR 1926.110; OSHA seeks to reduce asbestos exposure by setting standards to exposure in the construction activities such as demolishing of structures containing asbestos, removing of asbestos-containing material (ACM), repairing, altering, renovating or maintaining asbestos-containing structures, cleaning of asbestos, installing asbestos containing products and storing, transporting, and containing asbestos-containing products or asbestos itself in the construction sites (OSHA, 2012).. In section 29 CFR 1926.110 of the OSHA (2012, p.4) standards on asbestos exposure, employers in the construction industry are required to determine employee exposure measurement “for breathing zone air samples representing the 8-hour TWA and 30-minute short-term exposures for each employee to ensure that no employee is exposed to an airborne concentration of asbestos in excess of 0.1 f/cc as an 8-hour time-weighted average (TWA).”

Therefore, the standard exposure level of asbestos in the United States encourage that airborne concentration of asbestos should not exceed 0.1f/cc in 8 hours of working. The initials f/cc stand for Fibers per Cubic Centimeter, which is the unit used for measuring the concentration of asbestos in the air. In addition to ensuring that the airborne concentration of asbestos does not exceed 0.1f/cc in 8 TWA, OSHA requires employers to ensure that employees remain protected from being exposed to an airborne concentration of asbestos of about 1 f/cc on a sampling duration of 30 minutes. OSHA also requires employers in the construction industry to ensure that the general health and safety provisions provided in subpart 29 CFR Part 1926.20 for the construction industry are keenly followed to minimize employee exposure to asbestos fibers that may be detrimental to health and life of individuals.

OSHA believes that a negative exposure to asbestos is only achieved when a person’s exposure is consistently Permissible Exposure Limit (PEL). Employers are required to ensure frequent monitoring of the asbestos concentration and exposure among the employees by ensuring that an initial exposure assessment has been made. Initial exposure of asbestos in organizations must be tested, through a exposure monitoring, unless a negative exposure assessment has been conducted in a workplace environment to ensure that the persons involved are within the established PEL. More frequently OSHA requires that organizations should conduct initial exposure assessments, record their observations, information and calculations that significantly indicate employee exposure to asbestos and include any other initial monitoring. OSHA has also set an excursion limit of less than 1.0 of f/cc for over a 30-minute period in the construction sites. Therefore, employers in the construction industry are bound to uphold the excursion limits of 1.0 in 30-minutes work in asbestos manifested areas and 0.1 f/cc as an 8-hour time-weighted average (TWA) as the PEL.

In Australia, an organization known as Safe Work Australia (2013) provided this essay with an important information on the nature of standards and regulations established in this country. For Amosite, Chrysotile, Crocidolite, the standard exposure rate or the PEL of asbestos are at 0.1f/ml. The initials, 1f/ml refers to Fibers per Milliliter of air as scientifically provided by the method of membrane filter (Safe Work Australia, 2013). The measurement standards for determining exposure to asbestos in the United States and Australia are the same, the only difference is the units used in measuring the exposure levels whereby in the United States, experts use cubic centimeters, while in Australia, they use milliliter as the measuring unit. Australia has established standards for Short Term Exposure Limit (STEL). STEL is a standard procedure of determining short term exposure to asbestos in which experts determine exposure by assessing the time-weighted average for the maximum concentration of the asbestos fibers or elements in duration of 15 minutes.

In Quebec Canada, the Canadian government has imposed similar standards of ensuring that an employee exposure to asbestos in occupational situations remains limited for the maximum promotion of workplace health and safety (Safe Work Australia, 2013). In 2014, the Canadian government discovered that asbestos is the leading cause of workplace deaths and decided that it would revise its occupational exposure limits for asbestos to those that will guarantee the Canadians of maximum health and safety in their workplaces. Initially the Canadian Permissible Exposure Limit was 1 fiber per cubic centimeter but latest reports have shown that the Canadian government have suggested for the reduction of the limit to almost a zero level (Safe Work Australia, 2013). The government has suggested the emulation of the value that has been adopted by the American Conference of Governmental Industrial Hygienists (ACGIH), which stands at <0.1fiber per cubic centimeter (Safe Work Australia, 2013). The new standards came with a mandatory development of the asbestos exposure management program, which involves training employees involved in asbestos-related work activities.

Asbestos Dust Particulate Matter

As initially revealed in this report, asbestos contains fiber and dust particles, all of which are common agents that cause health complications to the construction workers involved in asbestos-related work activities. Fine dust from asbestos inhaled when constructors engage in direct mining of asbestos, milling of asbestos, repair, alteration or demolition of a building or even other managing structures containing asbestos, or constructing a house using materials that have asbestos, has associated with health implications. In Australia, the standard exposure rates for dust from asbestos and other sites involved with the use of asbestos have been similar in most cases. In Australia, the standards of OSHA also apply. The Workplace Exposure Limit (WEL) for Inhalable/inspirable dust, crystalline silica, and inhalable dust are in place. Inhalable crystalline silica is often the most regulated dust particle in Australian workplaces.

For crystalline silica, which may contain cristobalite, quartz, and trydimite as the inhalable dust, the standard exposure limit is 0.1 time-weighted averages (TWA) in milligrams per cubic meter (mg/m3) (Environmental Protection Agency, 2015). The standard exposure to Inhalable/inspirable dust from construction sites where asbestos is commonly present is currently at 10 particles for unspecified time-weighted averages (TWA) in milligrams per cubic meter (mg/m3) (Environmental Protection Agency, 2015). In Canada and Australia, the above standards have been implemented and organizations, especially those in the construction industry where exposure to dust is common, have been encouraged to ensure that employees are not exposed to extreme conditions where crystalline particles are likely to cause harm. Crystalline silica is a harmful dust that can predispose workers to serious health implications. According to Antero, Cantor, Attfield and Demers (2012, p. 290), scientists have discovered that “neutrophils and macrophages are the source of reactive oxygen and nitrogen species triggered by phagocytosis of crystalline silica (quartz) or asbestos fibres” and hence, the dust particle contributes to workplace exposure to asbestos fibers.

Noise/Sound Pollution

More frequently, noise is produced when carrying out an abrasive demolition of the structures, constructing sections of the buildings, earthmoving, excavation, concrete work or highway and tunnel construction, causes noise that often results in considerable harm of those living around the environment where these construction activities are ongoing (Environmental Protection Agency, 2015). To control exposure to extreme sound that may harmful, the United States, United Kingdom, Canada and Australia have their own standards that constructors must observe in the workplace. In the United State, the Clean Air Act that was established under the Environmental Protection Agency has been important in determining the standards and limits for noise pollution in the United States (Environmental Protection Agency, 2015). Clean Air Act Section 201 has encouraged constructions employers to strictly follow this Code to ensure proper noise abatement and authorization of appropriations (Environmental Protection Agency, 2015). On average, EPA had established long term exposure limits to sound of <75dBA or <75 decibels as the standard sound exposure that workers should sustain in a working environment where noise is a common part of the job process.

EPA also recommends a second limit of <70decibels to avoid hearing impairment. In most cases, workers exposed to extreme noise beyond <70decibels are likely to develop hearing impairments or difficulties in hearing. According to Hammer, Swinburne and Neitzel (2014, p.116 ) “the U.S. EPA recommends an average 24-hr exposure limit of 55 A-weighted decibels (dBA) to protect the public from all adverse effects on health and welfare in residential areas.” In other countries, the limits for exposure to noise pollution are relatively higher and stricter than Australia. In 2007, the Australian federal government reduced the limit for workers daily exposure to noise pollution from the initial level of 90 dBA to 85 dBA for estimated 8-hours official time for work in most organizations, including the construction industry (Joo, Yoon, Koo, Kim & Hong, 2012). The exchange rate for noise was also reduced from the initial 5 dBA to 3 dBA between places.


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