By Eric Pylkas
Insight IH Consulting is very experienced in organic solvents assessment. We have performed hundreds of personal breathing zone evaluations at client sites. Insight also can utilize real-time monitoring on employees and in areas for a detailed view of indoor air concentrations.
Solvents are substances capable of dissolving or dispersing one or more other substances. Organic solvents are carbon-based solvents (i.e., they contain carbon in their molecular structure). Millions of U.S. workers are exposed to organic solvents that are used in such products as paints, varnishes, lacquers, adhesives, glues, and degreasing/cleaning agents. Solvents also feature in the production of dyes, polymers, plastics, textiles, printing inks, agricultural products, and pharmaceuticals.
NIOSH recognizes many organic solvents are recognized as carcinogens (e.g., benzene, carbon tetrachloride, trichloroethylene), reproductive hazards (e.g., 2-ethoxyethanol, 2-methoxyethanol, methyl chloride), and neurotoxins (e.g., n-hexane, tetrachloroethylene, toluene). Many different classes of chemicals can be used as organic solvents, including aliphatic hydrocarbons, aromatic hydrocarbons, amines, esters, ethers, ketones, and nitrated or chlorinated hydrocarbons.
Organic solvents are present in many commonly used chemicals, including those found at the local hardware store. In particular, stripper chemicals that contain methylene chloride should be avoided. This is because methylene chloride is an OSHA standard chemical, with numerous requirements of employers. Additional informational links are provided below that provide detail about select organic solvents:
Lethal Exposure to Methylene Chloride during Bathtub Refinishing
Two cases of acute toluene intoxication
An array of options is available for the evaluation of workplace exposures to solvents. Active sampling tubes and passive organic vapor monitors can provide information on full-shift and short-term worker exposures. Additionally, photoionization detectors (PIDs) can provide real-time data regarding changing concentrations over finite periods of time (second-long intervals, if needed). PIDs are complicated instruments! See the Insight IH Consulting article, “Industrial Hygiene Misconceptions #3 – PIDs: Lamps and Response and Electron Volts…Oh My!” for more information. Insight will consider three primary limits when evaluating for organic solvents:
Ceiling Concentration – Select solvents have ceiling concentrations. OSHA has published a list of such chemicals in Table Z-2. Sampling for ceiling exposures involves targeting a duration sufficient to meet the minimum sample volume in the sampling method.
15-minute Short-term Exposure Level (STEL) – Many solvents have a short-term limit (typically 15-minutes) in addition to a full-shift limit. Compliance with these limits is determined through the evaluation of worst-case processes and activities.
Full-shift Time-weighted Average (TWA) – Most solvents have an 8-hour exposure limit. These are full-shift limits, where the average concentration over 8-hours is compared directly to applicable exposure limits (OSHA, ACGIH, NIOSH, AIHA, etc.)
– The mixture calculation is an often overlooked limit that is applicable to many solvents. OSHA’s Air Contaminants standard provides a formula for assessing exposures to chemicals with additive effects. This calculation is used when the components in the mixture pose a combined threat to worker health and components in the mixture effect the same body (target) organ or physiologic system. This formula (shown below, Equation 3) is suitable for simultaneous exposures or for TWA exposures that occur consecutively within the same work shift.
Em = (C1 / L1 + C2 / L2) + … (Cn / Ln)
Em = equivalent exposure for the mixture (Em should be less than or equal to 1 for compliance)
C = concentration of a particular substance
L = PEL
Insight IH Consulting has extensive experience in industrial hygiene assessments for organic solvents. Available methods include active glass tubes, passive charcoal badges, and photoionization detectors (PIDs).
20 February 2019
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