In this post you'll learn
Overview:
Benzene is an organic chemical compound composed of six carbon atoms bonding with six hydrogen atoms in a circular pattern. It’s usually colorless but can also display a light-yellow color. Benzene has a sweet smell, and it is highly flammable.
It is commonly used as an intermediary in plastic, nylon, and resin production. Additionally, it is frequently encountered in the petroleum industry due to crude oil’s benzene content. Benzene is also used as an additive in gasoline production to increase octane levels.
Due to its toxic and flammable nature, benzene can be hazardous to humans.
Hazards:
Effects on benzene depend on exposure type, duration, and frequency. Studies show that inhalation and dermal contact causes low levels of toxicity, while ingestion of benzene leads to higher levels of exposure. Contact with benzene or benzene vapor may cause irritation and blisters on the skin, eyes, and respiratory tract. Furthermore, breathing benzene in excessive amounts may cause rapid or irregular heartbeat, unconsciousness, and death at very high levels. Digestion of food contaminated by benzene may result in convulsions, vomiting, and death.
Prolonged exposure to benzene causes dysfunctions such as reduced production of red blood cells and reduced immune efficiency. In addition, due to the negative effects of benzene on bone marrows, cases of a decrease in bone volume and strength may occur.
As mentioned earlier, benzene is highly flammable. Therefore, the effects caused by its toxic nature are not the only threats posed by its presence. Benzene reacts with oxidants and halogens dangerously, causing explosion risks. Benzene evaporates very quickly. With vapor denser than air, it causes it to sink to low-lying areas. Easily generated vapor can compose explosive mixtures with oxygen. The lower explosive limit (LEL) for benzene in the air is 1.2% while the upper explosive limit (UEL) is 7.8%. Due to benzene’s low flash point, mixtures of benzene and air can easily ignite by heat, sparks, or flames. Storing benzene can be particularly dangerous. As such, cases of overheated containers igniting without direct contact with sparks or open flame have been reported.
To prevent the hazards stated above, workplaces that are exposed to benzene must be continuously monitored. Establishing accurate benzene detection systems plays a big role in providing a safe work environment.
Detection:
There are two main methodologies used for assessing benzene levels at workplaces: real-time monitoring and sample analysis.
Sample analysis is useful when accurate measurements of benzene levels of an area are desired. In addition, with thorough sample analysis, benzene levels of soil and water can be analyzed as well as air. Sampling air and soil are quite straightforward: a required amount of water or soil is collected inside a container that is free of contamination by syringes or scoops. Skin and eye protection must be used to eliminate exposure to risky samples. On the other hand, air samples can be collected in a multitude of ways. Air samples can be collected by trapping whole air in a canister or by utilizing absorbents. Moreover, portable vapor monitors collect air samples accurately. They can be attached to work uniforms that collect samples from the personal breathing space, or they can be placed in areas with suspected benzene exposure.
After collection, the sample is analyzed by gas chromatography (GC), the process of separating substances capable of vaporizing by inert gases or thermal desorption. After separation, mass spectrometers are used to quantify benzene levels of the sample. As a quick and reliable sample analyzing method, colorimetric tubes can be used as well. To use colorimetric tubes, a sampling pump is inserted into the end and then operated to suck air inside. When air contacts the reagent, a chemical reaction starts and the color changes. The duration of this reaction provides a fast and reliable measurement of benzene saturation.
In contrast, real-time monitoring is useful when benzene levels are periodically checked. Photoionization detectors or PIDs, use high-energy photons to break down into charged particles. Afterwards, conducted electrical charges are measured to quantify benzene saturation.
Another alternative tool for real-time monitoring is volatile organic compound (VOC) detectors. They are used to measure VOC concentration such as benzene along with other organic compounds.
Portable versions of real-time monitoring tools are available for accurate measurements in remote workplaces or confined spaces.
In addition, multi-stage monitoring systems are widely used due to the extremely dangerous properties of benzene. These systems utilize different methods of benzene detection in combination to establish fail-safe mechanisms. In case of equipment failure, other implemented systems still provide readings for additional layers of safety.
Regulations:
Occupational Safety and Health Administration (OHSA) 1910.1028 App D: Standard of Sampling and Analytical Methods for Benzene Monitoring and Measurement Procedures dictates that samples collected to analyze benzene exposure must provide realistic analytical results. To ensure accuracy, the exposure time must be taken into consideration. A single sample that has been exposed to benzene for 8 hours can be used, as well as two samples within 4 hours of exposure time. Short-time interval samples can also be used. With random sampling, five different samples must be taken randomly throughout the shift. The arithmetic average of all samples is used to calculate benzene exposure levels.
According to OSHA, monitoring methods must provide a minimum of 95% accuracy, and benzene exposure must not exceed the permissible exposure limit, which is 1 ppm for 8 hours. Although it’s important to keep in mind that medical experts recommend zero exposure to benzene due to its destructive effects on human health.
Conclusion:
Benzene is an organic compound that poses many hazards in workplaces. Its contact can cause devastating effects on organic tissue as well as cause body dysfunction on prolonged exposure. In addition, due to its high flammability, high concentrations of benzene can result in destructive explosions.
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