Patty's Industrial Hygiene, Hazard Recognition. Группа авторов

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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.

Table 6 Likelihood levels.

       9.1.5 Risk Treatment Options

      Using the hierarchy of controls model, the assessment team and management reviewed possible solutions. Recognizing that higher‐level controls would be more effective and reliable, management stated that higher‐level controls should be strongly considered. It should be noted that this PtD example is a redesign of an existing process, not a new design.

      For concern #1, a review of available substitutions for pure SO₂ suggests lower concentrations of SO₂ (aqueous solution) and powdered, granular, and tablet forms of potassium meta‐bisulfite. Costs for existing chemicals and procedures were determined and compared to the proposed solutions and their projected costs. It was determined that the costs of substituting with the less hazardous forms of SO₂ were about the same as the cost of pure SO₂, but other benefits of using the less hazardous products were the elimination of potential releases of highly hazardous chemicals to the surrounding community, improved employee morale and enhanced management goodwill, and reduced compliance costs and efforts. For concern #2, the location of the DMDC metering machine directly placed in the congested bottling area was evaluated.

      It became apparent that the machine could be relocated away from the bottling area with piping to the bottling system. Similar benefits such as employee health, improved morale, management goodwill, and increased space were considered.

       9.1.6 Risk Treatment Selected

For concern #1, the winery decided to replace (substitute) pure liquefied SO₂ with much less hazardous 6% SO₂ solution and potassium meta‐bisulfide tablets. For concern #2, until the bottling line can be relocated to a more open area with good ventilation, it was decided that the DMDC metering equipment should be removed (eliminated) from inside the bottling room and relocated outside the building with hard piping into the bottling room (Figure 11).

Table 7 Risk levels.

      Where: Dark gray indicates high risk; Light gray indicates serious risks; Gray indicates medium risk; Light dark gray indicates low risk.