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and do require serious attention. FSI exposures that can result in environmental releases, explosions, and disasters have been found to involve some of the following factors (14):
Unusual and nonroutine work
Nonproduction tasks
Facility modification or construction activities
Shutdowns and startups for repair and maintenance tasks
Exposure to high‐energy sources (e.g. electrical, steam, pneumatic, chemical)
Upsets (situations going from normal to abnormal).
Management agreed that the need to eliminate or reduce these FSI risk level exposure was required. With management input, the risk assessment team established risk criteria to be used for the assessment.
As determined in the initial investigation, concerns were identified by employees handling pure liquified sulfur dioxide in the dosing of wine tanks, and in the use of the DMDC dosing machine. A simplified PHA method was used to help identify hazards, analyze, and evaluate their risk levels, prioritize actions, and select controls using the hierarchy of controls model (Figure 8). The primary concerns were the use and storage of 100% liquified SO2 and DMDC.
9.1.1 Concern #1 – Sulfur Dioxide
SO2 is used to protect wine from yeast and microbial growth, which can spoil or reduce its quality. The winery purchased the 100% liquified SO2 concentration thinking that it was cheaper to purchase it in the pure form and would require less frequent purchasing. SO2 at 100% concentration presents several significant concerns, including the safety and health of employees (risks include death and blindness) and environmental reporting requirements. The Cal‐OSHA PEL is 2 ppm, and the lethal dose is 100 ppm. Sulfur dioxide gas is heavier than air (density 2.83 kg m–3) and can accumulate in closed areas. The configuration and limited ventilation of the bottling areas present a risk to employees, should a SO2 release occur.
FIGURE 8 Simplified PHA.
In addition, the quantity of 45 gallons, which weighs 548 lbs., exceeds the threshold planning quantity (TPQ) of 500 lbs. for US Environmental Protection Agency (EPA) SARA Title III Sections 302 and 304, Extremely Hazardous Substances. Potential FSI scenario from a release of SO2 in a 100% liquid concentration used to dose large tanks outside and inside buildings during the winemaking process. The dosing process required employee to dispense a small amount into a dosing instrument that attaches to the bulk tank inside the building. Figure 9 shows the filling and dispensing process equipment and tanks.
9.1.2 Concern #2 – Dimethyl Dicarbonate
DMDC is a microbial control agent used in place of filtering to prevent spoilage of wine. Trained operators and special equipment are used to dose the wine in a closed system. The location of the DMDC metering equipment (shown in Figure 10) in the bottling area presented a potential exposure to bottling employees in the event of a release. The bottling area had limited ventilation and limited means of escape.
FIGURE 9 Pure sulfur dioxide liquid filling and dispensing.
FIGURE 10 DMDC dosing machine in bottling area.
In the event of a release of DMDC, the bottling crew would be vulnerable. Human studies have shown that DMDC is a highly corrosive skin irritant and that dermal contact may result in irreversible skin damage, scale formation, and necrosis. DMDC is known to cause adverse effects on the respiratory system as well (15).
The SDS for DMDC indicates that its exposure ceiling limit is 0.04 ppm, a very small quantity, which means any release can lead to severe exposure. In the “Safety Precautions When Handling DMDC” from the manufacturer, it states that DMDC is toxic if inhaled and should only be used in well‐ventilated areas. In addition, the document warns that in the event of a spill or release, personnel must be evacuated immediately. According to the SDS, the odor of DMDC cannot be used as a warning against inhalation exposure, and that “a NIOSH approved air‐purifying organic vapor respirator must be used when concentrations are between 0.04 and 10 ppm”; and “positive pressure air‐supplied respirators if concentrations are unknown or exceed 10 ppm or if the workspace is confined and unventilated” (8).
9.1.3 Risk Analysis
Using Tables 5 and 6 to estimate severity and likelihood levels, the two concerns were analyzed. The risk assessment team reviewed available information and performed the risk analysis using the PHA format shown in Figure 8. In the current state, both the SO2 and DMDC risks were estimated to have a risk level of 12, an unacceptable risk level to the organization. Both risks were estimated to have a severity level estimated at 4 or “catastrophic” and a likelihood level of 3 or “very likely.” The PHA risk assessment tool provides a comparison of the risk levels before and after recommended risk treatment measures are implemented.
9.1.4 Risk Evaluation
With the risk analysis performed, management evaluated the need for action for these two risks. The management team determined that the risk levels for both concerns were unacceptable to the organization, using Table 7 as its rating system.
Table 5 Severity levels.
| Severity level | Definition |
|---|---|
| Catastrophic (4) | Fatalities; damage to community, environment, and reputation |
| High (3) | Permanent disability injury or illness; multiple injury events |
| Moderate (2) | Injury or illness requiring medical attention |
| Low (1) | Minor injury or first aid incident |
Table 6 Likelihood levels.
| Likelihood level | Definition |
|---|---|
| Very likely (4) | Will happen under right situations; has occurred multiple times |
| Likely (3) |
|