Case Study: Assessing Exposures to 1-Chloro-4-(Trifluoromethyl) Benzene (PCBTF) in U.S

Case Study: Assessing exposures to 1-chloro-4-(trifluoromethyl) benzene (PCBTF) in U.S. workplaces

Supplement Document - Detailed Workplace Description

We recruited four vehicle manufacturing plants through personal contact and three paint manufacturing plants via contacting American Coatings Association. All manufacturing plants were identified by code for confidentiality.

Vehicle manufacturing plants

Plant A: This helicopter manufacturing plant used PCBTF as a cleaning solvent for removing residual glue after upholstery removal during interior refurbishment. During the full-shift, each interior refurbishment worker used approximately 1 liter of PCBTF. They applied PCBTF solvent to disassembled sections of air conditioning ducts, interior shrouds, ceiling upholstery, and other interior parts using a paint brush. After applying PCBTF, the worker covered the area with a thin plastic sheet for 3-5 minutes. The parts were then scraped clean of adhesive using a putty knife, steel wool, commercial cleaning pads, and cheese cloth. The pads or cloth were routinely dipped directly into the liquid solvent during use. Although all work should be performed under a slotted back-draft ventilation hood in a room, we observed that parts often overhung outside of the face of the hood during this task. The room was controlled by general ventilation and workers wore safety glasses and nitrile gloves. (Earplugs were optional.) No respirator was worn during this task.

Plant B: PCBTF was used in this aircraft manufacturing plant during primer application before coating of an airplane. The primer contains 85 liters of base, 43 liters of activator, and 43 liters of thinner, and only the thinner contains 60%–100% PCBTF and mixed at the facility. During the field survey, five painters worked on an airplane by spraying the primer in all directions (i.e., overhead, forward, and downward) using spray guns. Each painter wore a hood airline respirator, Tyvek® suits, and latex or nitrile gloves while working on a moveable platform to reach all areas of the aircraft. The priming work took about 35–40 minutes. The room was controlled by downdraft ventilation during the task and general ventilation while no painting work was performed.

Plant C: PCBTF was also used in this aircraft manufacturing plant during primer application before coating of an airplane. In a mixing room, a mixing worker wearing a full facepiece air-purifying respirator placed 23 liters of base (0% PCBTF), 23 liters of activator (30%–60% PCBTF), and 6 liters of thinner (60%–90% PCBTF) in a large mixing vat to mix the chemicals under a canopy hood. The chemical was then dispensed from the vat into 20-liter buckets placed on carts for delivery to the painting room. Buckets were covered after being dispensed. The mixing area was controlled by general ventilation and natural ventilation by opening garage doors. In the painting room, four painters divided the primer evenly and applied it to the airplane using airless electrostatic spray guns. Each painter wore a hood airlinerespirator, Tyvek® suits, and latex or nitrile gloves. The room was controlled by downdraft ventilation during the task and general ventilation while no painting work was performed.

Plant D: This plant makes delivery trucks. The rounded edge panels that join the sides and roof had traditionally been made from aluminum. However, the plant considered replacing them with a molded plastic and made a test truck that way. After attachment of the plastic panels to the truck body, PCBTF was used to roughen the plastic surface before primer and paint could be applied. Two painters applied the plastic adhesion promoter (88% PCBTF) to each side of the truck using cup spray guns in a downdraft ventilation booth in a large room controlled by general ventilation. The PCBTF application took about 15 minutes and each painter wore coveralls, gloves, and airline respirator.

Paint manufacturing plants

Plant E: This paint manufacturer used PCBTF as a component in the synthesis of automotive coating materials. Four tasks—pre-batch making, batch making, filling, and quality control testing—were observed during the field survey. In the pre-batch-making area, the pre-batch worker dispensed PCBTF from 210-liter drums into 20-liter buckets. The room air circulation was controlled by a slotted back-draft hood, and workers wore nitrile gloves, safety glasses, and flame-retardant uniforms. No respirator was worn during the pre-batch making task. In the batch-making area, a single worker usually worked on one batch per shift; tasks were loading raw materials into the tank and product mixing. Raw materials in drums were loaded directly to the tank several times throughout the batch synthesis process by using a pump in a closed system. During the full shift, the solvent contact time was 30–60 minutes. The amount of PCBTF handled by batch makers during the survey ranged from 1,000 to 3,200 liters per worker per shift. The batch maker added pigments and other materials manually via a slotted hopper where the top was attached to elephant-trunk local exhaust ventilation. The batch maker wore nitrile gloves, safety glasses, hearing protection, and a flame-retardant uniform for a full-shift and plus N-95 facepiece respirator to remove particulates during manually adding materials. Filling operators typically filled 20-liter pails with paint materials from an automated dispenser on a conveyor line. During the survey, one filling operator handled about 300 liters of PCBTF, and the other handled about 4,500 liters of PCBTF. A 4-inch flexible duct, local-exhaust, was placed near the filling station, and 20-liter pails were purged with nitrogen until filled to remove moisture. The filling operators wore nitrile gloves, safety glasses, hearing protection, and a flame-retardant uniform and no respirator was required. A laboratory quality-control worker came on to the batch-making area to take product samples for quality control analysis in a separate laboratory area. The quality-control worker wore nitrile gloves and safety glasses. No respirator was required for this task. The whole facility was controlled by general ventilation in addition to any local ventilation systems.

Plant F: This paint manufacturer used PCBTF as a component in the synthesis of automotive coating materials. Four tasks—cleaning, batch making, filling, and batch adjusting—were observed. The cleaning workers were responsible for cleaning the small tanks and parts from the batch-making area with solvent containing PCBTF under a slotted back-draftventilation hood at the cleaning station. In the batch-making area of the small-order department, workers added pigment, solvent, and thinner to tanks for producing batches less than 950 liters in size. The smaller tanks were open to the atmosphere where the room was controlled by general ventilation during the mixing, pouring, and grinding. The batch-makers wore half facepiece respirators with dual cartridges to remove volatile organic chemicals and particulates when manually adding materials. The filling operators in the filling area added material to small, portable containers, mixed the material, poured the mixed material into finished goods containers, and labeled the containers for final distribution. These activities were done under a local-exhaust, flexible duct located at the mixing and pouring stations. No respirator was worn during this task. One batch adjuster took the samples from each tank operating in the modular order department area (producing batches greater than 950 liters in size) from an opening in the top of the tank. The batch adjuster then took the samples to a quality-control laboratory for analysis. The batch adjuster also added materials to the tank at the discretion of the quality control unit. Material addition took place under a pull-down-style, local-exhaust, duct with a nitrogen blanketing system at the top of the tanks to control vapor release. The batch adjuster wore a half facepiece respirator with dual cartridges to remove volatile organic chemicals and particulates when manually adding materials.

Plant G: This paint manufacturer used PCBTF as a component in the synthesis of automotive coating materials. Two separate surveys were performed at this facility. Five tasks—pre-batch making, batch making, color mixing, filling, and pilot working—were observed in 2011. Three tasks—pre-batch making, batch making, and filling—were observed in 2012. Below is the detailed description for each task.

In the pre-batch-making area, two workers per shift prepared materials according to work orders to be used at the batch-making area. Once they brought materials from the warehouse, they transferred the materials to other containers (typically a 75–110-liter container or drum) using either a pumping system or a mechanized pouring system. Only the inlets of the containers were open. The filled containers were then delivered to the batch-making area for mixing. The pre-batch-making area was controlled by general ventilation. The two sides of the room that were connected to the warehouse had no doors, and two garage doors on one side of the area were open during the survey. Pre-batch workers wore safety glasses, uniforms, safety shoes, and nitrile gloves. Respirators were not required.

In the batch-making area, each worker dosed various chemicals in a batch container, mixed the chemicals for a certain time, transferred the chemicals to other containers, and cleaned the emptied batch containers. Typical batch sizes were 320, 1,800, and 6,400 liters. The batches were always enclosed except for cleaning or when partially opened while adding/transferring materials. They also cleaned batch containers manually, using a brush to remove thick materials then draining the remaining residue to another container. Batch-making workers were required to wear safety glasses, uniforms, nitrile gloves, and safety shoes while performing normal tasks, all personal protective equipment (PPE) plus dust masks and Tyvek suits when adding pigments into a batch, and all PPE plus Tyvek suits and half facepiecerespirators for cleaning spilled materials. We observed, however, that workers did not wear respirators when cleaning spilled materials and manually washing containers. The batch-making area located north of the manufacturing area was controlled by general ventilation. During our visit, two garage doors near the batch-making area were open.

In the color-blending unit, a mixing worker added tins of pigment to small batches (< 950 liters) several times over an 8-hour shift. A circular, local-exhaust, flexible duct was present 0.3 m above and 0.3 m behind the mixing containers, and noticeable suction close to the opening was observed. The worker wore nitrile gloves, eye protection, safety shoes, earplugs, and dust mask (for adding materials). The area was controlled by general ventilation.

In the filling area, a worker filled the final products into 3.8-liter (1 U.S. gallon) containers from an automated dispenser on a conveyor line, and the other worker placed the filled containers into boxes. The three sides of the automated dispenser were covered with acrylic sheet. Once they finished filling and packaging, the workers cleaned the empty batches using N-butyl acetate. Both workers wore uniforms, safety glasses, safety shoes, cotton gloves (for filling and packaging), and nitrile gloves (for cleaning) and no respirators were required. The area was controlled by general ventilation.

A pilot facility worker mixed and blended samples (20 liters or less) of paint formulations. General exhaust ventilation was present in the mixing room. The worker then sprayed and tested sprayed samples under a local-exhaust-ventilation hood in a small room. The PPE used for this task were nitrile gloves, safety glasses, safety shoes, earplugs, and lab coat. No respirator was worn during this task.