Industrial Hygiene and Toxicology - Research Paper Example

Industrial Hygiene and Toxicology Introduction Formaldehyde, naphthalene and hexavalent chromium are some of the toxic chemicals used in different industries. As part of the safety measures of the government, the National Institute for Occupational Safety and Health (NIOSH) mandates the different industries to monitor the exposure of the employees to these chemicals, as well as the monitoring of the presence of these chemicals in the workplace. This paper discusses the toxicological effects of the above-mentioned chemicals and the NIOSH requirements for their analysis. Formaldehyde Brief Description of the Chemical and Its Uses Formaldehyde is a clear colorless liquid, with a pungent suffocating smell. It is usually present in aqueous solutions and the fumes produced are flammable. It is a strong oxidizing agent and has a tendency to polymerize (“Formaldehyde”). Formaldehyde is one of the major chemicals used in the industry. Generally, it is used as an intermediate in resin production and for synthesis of other chemicals. It has also been used as a fungicide or bactericide and is one of the components in the manufacture of consumer items such as cosmetics and glues (“Uses of Formaldehyde”). Exposure and Prevention The typical exposure routes of formaldehyde are through inhalation, skin contact or through the eyes (“Formaldehyde”). NIOSH recommends that proper Personal Protective Equipment [PPE] be worn to prevent exposure to the chemical. The eyes must be protected by wearing safety goggles during work. The type of PPE to be worn when airborne formaldehyde is present depends on its present concentration in the workplace. The permissible exposure limit [PEL] of formaldehyde is 0.75 parts per million part of air [ppm] measured as an 8-hour time weighted average [TWA], with a 2 ppm short-term exposure limit [STEL] (“Formaldehyde”). At concentrations 10 times the PEL, NIOSH requires a full-facepiece respirator which has cartridges specific to prevent formaldehyde from being inhaled. When concentration reaches 100 times the PEL, a full-face mask respirator with industrial size cartridge or a Type C supplied air respirator or continuous flow hood is needed (“Appendix E”). NIOSH Methods of Sampling and Testing NIOSH has a manual for the determination of hazardous chemicals in the workplace. NIOSH Method No. 2541 for the determination of formaldehyde uses a gas chromatograph [GC] equipped with a flame-ionization detector [FID]. Formaldehyde in the air is sampled by using a pump attached to a sorbent bed where the fumes of formaldehyde are adsorbed. These tubes are then washed with toluene and sonicated for one hour. The solution obtained is injected to the GC. There are no reported interferences for this method of formaldehyde analysis (“Formaldehyde: Method 2541” 3–5). Naphthalene Brief Description of the Chemical and Its Uses Naphthalene is characterized by the mothball scent and its color ranges from colorless to brown. It is considered to be combustible but requires a high amount to be present before it can be ignitable. This chemical is incompatible with oxidizing agents and chromic anhydride (“Naphthalene”). The most important use of naphthalene is in the manufacturing of phthalic anhydride. It is also used as insect repellent, particularly as mothballs. Other uses of naphthalene are in dye industry and manufacturing of resins (“Naphthalene”). Exposure and Prevention The routes of exposure of naphthalene are through inhalation, ingestion, skin or eye contact and skin absorption. NIOSH has set the exposure limit to 10 ppm TWA (50 mg/m3) and STEL 15 ppm (75 mg/m3). To uphold the safety in the workplace, contact with the chemical must be prevented depending on its concentration in the area. When the naphthalene concentration is below 100 ppm, any half-mask respirator that has an organic cartridge can be used, e.g., N99 or N95. When the area has an unknown concentration of naphthalene, a full facepiece respirator must be used, including an auxiliary breathing apparatus (“Naphthalene”). NIOSH Methods of Sampling and Testing NIOSH recommends Method No. 1501 for the analysis of naphthalene in the workplace. The measurement also requires a gas chromatograph equipped with an FID. This method can be used for in TWA determination of aromatic hydrocarbons since naphthalene is an example of this type of organic compound. Other volatile compounds present in the atmosphere where sampling was conducted can be expected interferences. Similar to formaldehyde, a pumping system with a sorbent tube is used for sampling. The sorbent material is washed with carbon disulfide to wash out all the organic compounds, and this solution is injected to the GC (“Hydrocarbons, Aromatic: Method 1501” 1–2). Hexavalent Chromium Brief Description of the Chemical and Its Uses Hexavalent chromium falls under the chromates and chromic acid category of NIOSH. Generally, chromates are characterized by their dark red to orange color, which are odorless. It is corrosive to metals and is a strong oxidizing agent (“Chromic Acid”). Chromium (VI) and chromium (III) are used in the production of dyes and other pigments. It is also used in the leather industry as a tanning agent (“Chromium”). Chromates are known carcinogens; hence, its presence in the work environment must be properly monitored to keep the employees safe (“Chromium, Hexavalent: Method 7600” 1). Exposure and Prevention Similar to the two chemicals discussed earlier, hexavalent chromium can enter the body through inhalation, by swallowing and by skin or eye contact. NIOSH recommends that REL for this chemical is TWA 0.001 mg/m3. With this very low exposure limit, NIOSH recommends the use of a face-mask with auxiliary air supply at concentrations of chromium above the NIOSH REL. When using dilute solutions, masks with proper cartridges can be used (“Chromic Acid”). NIOSH Methods of Sampling and Testing There are several methods recommended by NIOSH in determining the amount of hexavalent chromium and its related substances. These methods are Methods no. 7600, 7604, 7605, 7703 and 9101 (“Chromic acid”). Method 7600 uses spectrophotometry as the analytical technique. The instrument used for this analysis is a visible absorption spectrophotometer. Interferences which have been identified for this method are: copper, iron, vanadium and nickel. Techniques to decrease the interference of these elements are also available in the literature (“Chromium, Hexavalent: Method 7600” 1). The sampling technique involves a pumping system attached to a sampler containing polyvinyl chloride (PVC) filter. The sampling procedure is carried out for one hour and the filters are placed in a vial, waiting to be dissolved in a proper solvent. Chromium (VI) is extracted from the filters with a series of solutions of dilute sulfuric acid and then with base. Diphenylcarbazide solution is used to derivatize Chromium (VI) and then the sample solutions are read in the spectrophotometer (“Chromium, Hexavalent: Method 7600” 2). Works Cited “Appendix E – OSHA Respirator Requirements for Selected Chemicals: Formaldehyde.” Centers for Disease Control and Prevention. 18 Nov 2010. Web. 18 Nov 2012. “Chromic acid and chromates.” Centers for Disease Control and Prevention. 18 Nov 2010. Web. 19 Nov 2012. cdc.gov. “Chromium.” Navy and Marine Corps Public Health Center. n.d. Web. 18 Nov 2012. “Chromium, Hexavalent: Method 7600.” Centers for Disease Control and Prevention. 15 Aug 1994. Web. 19 Nov 2012. “Formaldehyde.” Centers for Disease Control and Prevention. N.d. Web. 18 Nov 2012. cdc.gov. “Formaldehyde: Method 2541.” Centers for Disease Control and Prevention. 15 Aug 1994. Web. 19 Nov 2012. “Section III. Properties, Manufacture and Uses of Formaldehyde.” Occupational Safety and Health Administration. 27 May 1992. OSHA.gov. “Hydrocarbons, Aromatic: Method 1501.” Centers for Disease Control and Prevention. 15 Mar 2003. Web. 18 Nov 2012. cdc.gov. “Naphthalene.” Centers for Disease Control and Prevention. 18 Nov 2010. Web. 19 Nov 2012. cdc.gov. “Naphthalene.” Environmental Protection Agency. 11 Jun 2007. Web. 19 Nov 2012. epa.gov. Read More