Hazards continued evaluations

After potential hazards have been identified, site access and hazard controls should be developed and put in place before work begins. This process of recognizing and evaluating new hazards and putting controls in place continues until the task or job analysis is complete. In addition, as mentioned earlier, as new information is discovered or becomes available, this should be immediately considered. If an amendment is in order, this should be completed and communicated to all involved. 

If the PA reveals that a contamination problem exists, but does not pose an immediate threat that warrants a removal, U.S. EPA will continue to study the site during a site inspection (SI). Based on data collected during the PA and the SI, U.S. EPA will evaluate the site using the hazard... 

Silverstein, J. L. et al., Loss Prev., 1981,14, 78 Nitrobenzene was washed with dilute (5%) sulfuric acid to remove amines, and became contaminated with some tarry emulsion that had formed. After distillation, the hot tarry acidic residue attacked the iron vessel with hydrogen evolution, and an explosion eventually occurred. It was later found that addition of the nitrobenzene to the diluted acid did not give emulsions, while the reversed addition did. A final wash with sodium carbonate solution was added to the process [1]. During hazard evaluation of a continuous adiabatic process for manufacture of nitrobenzene, it was found that the latter with 85% sulfuric acid gave a violent exotherm above 200° C, and with 69% acid a mild exotherm at 150- 170°C [2],... 

Facility System Safety (FSS), which is the application of system safety concepts to the facility acquisition process, has recently gained acceptance throughout the Department of Defense and most recently within the Department of Army with the conception of SAFEARMY 1990. The Army s goal is to fully integrate the total system safety, human factors, and health hazard assessments into continuous comprehensive evaluation of selected systems and facilities. The Chemical Research Development and Engineering Center (CRDEC) has mandated appropriate levels of system safety throughout the lifecycle of facility development for many reasons. These include ... 

In the hazard evaluation of the process, it was found that exotherms occurred with MNB-H2SO4 mixtures at temperatures above 150°C. The initiation temperature and extent of the exotherm depend on the acid concentration. During normal operation, the temperatures in die continuous stirred tank reactors and in the continuously operated separator are between 135 and 148°C. However, operating simulation showed that for certain feed rates well out of the normal operating range, the temperature could reach 180°C and a runaway is thus possible. 

Areas related to the evaluation of the adversity of an effect are reversibility and irreversibility and adaptation to an exposure. Irreversible effects are always of great concern. Reversible effects may also be of great concern depending on the nature of the effect and on the setting in which they occur. It cannot be mled out that a permanent lesion may have occurred even if the overt effect is transient. Eurthermore, when there is a more or less continuous exposure to a substance, the question of reversibility is not relevant because adaptation systems will be counteracted by new insults. In many cases it is not possible to draw any conclusion on whether an effect is reversible or not as such experimental data are rare, and all significant health effects that can impair function, both reversible and irreversible, should therefore be considered in the hazard assessment. 

In a NIOSH Health Hazard Evaluation of refrigeration workers exposed far below the threshold limit values (TLVs) for chloropentafluoroethane and chlorodifluoromethane, 27 workers were medically evaluated. Seventy-one percent complained of dizziness and lightheadedness compared with twenty-one percent of controls. Palpitations were reported in 36% of exposed and none of the non-exposed workers. No clinical neurological or electroneurophysiological abnormalities were detected in eight of the refrigeration repair workers followed for 3 years during continuous employment. ... 

Special process and product specifications have been set forth for companies in the chemical industry. Additionally, specific limits must be observed for pollutant or VOC (volatile organic compounds) emissions. Specific maximum allowable concentrations at workplaces must not be exceeded. Both the transport of chemicals and the recycling or disposal of chemical wastes are subject to particular requirements. Periodic hazard assessments - which in Germany, for example, are mandatory according to the Ordinance on Industrial Safety and Health (Betriebssicherheitsverordnung, BetrSichV) - are a must requirement in the chemical industry. To achieve a Continuous Improvement Process, product and process requirements must be identified, evaluated and monitored on a regular basis. 

In achieving this target, all countries should seek common, science-based, international standards. FSIS should continue to ensure that equivalent inspection systems and standards for meat and poultry products exist in all countries exporting such products to the United States, especially in light of the better US safety standards expected under Hazard Analysis Critical Control Points (HACCP). FDA also should evaluate the food safety systems of other countries, with the purpose of entering into agreements with those countries having food safety systems that offer equivalent levels of public health protection to those of the United States or that can provide assurance that their products will be in compliance with FDA requirements. 

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