Vision in Chemistry
Laboratory - Avoid tissue injuries
After several hours of work, the laboratory chemist ignored the slight discomfort in his hand and worked to finish the long procedure. Shortly later, the discomfort became too intense to ignore. Upon removing his glove, he saw a red lesion on his palm and a yellow discoloration of his fingers. The pain was increasing in intensity rapidly. He was the victim of a pinhole leak in a glove. The investigation could not determine if the pinhole was present before he put on the glove or if it developed during the procedure. The glove material, however, was rated only as “moderate” for its protection against the chemicals being used in the procedure.
The plant maintenance man was carrying a plastic bottle of 50% Sodium Hydroxide solution (caustic soda). It slipped and landed on flat on the bottom. It did not break, but the cap popped off and a single drop of the chemical splashed directly into the employee’s eye. To his good fortune, there was a running water hose almost at his feet and he got running water into his eye within 10 seconds. His co-workers moved him to an eyewash station and continued to rinse his eye for about 25 minutes. His eye was rinsed during transport to the emergency room and then for another four hours in the E/R. While the pain diminished over this extensive rinsing, it did not end and he required pain control medication. Measurement of his visual acuity indicated that he was effectively blind in that eye. After all of the rinsing, the pH of his eye (measured by touching the sclera with pH paper) was about 10 – 10.5. The employee was able to return to work the next day and regained all of his vision within seven days. Thirty years later, he has no sequelae from this incident. He was NOT wearing any eye protection at the time of the incident.
Tissue injury from contact with chemicals is preventable. Use of appropriate engineering and procedural controls and using personal protective equipment (“PPE”) properly is essential. Here are some ideas to help you prevent injuries.
Wear adequate eye and face protection
>There are several types of eye and face protection available for chemical protection – safety glasses, splash goggles and face shields. The correct level of protection must be selected based on the risk for a given task. In second case cited above, the incident would have been completely avoided if the maintenance man was wearing simple safety glasses.
Maintain equipment and use equipment properly
PPE is not expected to last the entire working career of an employee. Indeed, some items, such as light weight gloves, may be placed many times a day, while safety shoes may last several years. The employee has a direct responsibility to maintain their PPE and to replace or repair it as needed. The employee also must use the equipment properly. In the first case cited above, there is evidence that the injury would not have happened if the technician had replaced his gloves every hour or so during the procedure.
Prevent exposure to corrosive chemical fumes and vapors
Inhalation injuries associated with corrosive chemicals can be prevented with properly engineered and used ventilation. A laboratory hood, a ventilation snout, or a vapor capture system will remove the offending chemical from the employee’s breathing zone. Given the potential severity of an inhalation injury, the proper use of these devices is essential.
Maintain adequate ventilation
General laboratory ventilation is adequate to remove routine vapor emissions. A laboratory hood is usually sufficient to prevent the accumulation of ignitable concentrations of flammable vapors during a laboratory procedure. If these assumptions are not clearly correct, the adequacy of ventilation must be investigated. Failure to do so could result in a flash fire or explosion.
Maintain and use adequate personal decontamination equipment
Even with properly designed systems, good procedures, and adequate PPE, occasional failures do occur which result in employee contamination. A prompt response with the correct decontamination equipment can prevent an injury or lessen its impact. While water has been the traditional decontamination agent, it has recently been shown to be lacking in efficacy. The DIPHOTERINE® solution is clearly superior.
Transport corrosive chemicals in secondary containment
The employee in the second incident cited was not using secondary containment or a stable transport device to move the caustic soda around the plant. If he had done so, the injury would have been avoided. Always move corrosive chemicals in an appropriate form of secondary containment. If possible, use a containment cart or transport device.
Pour chemicals properly
Handling processes should be designed to minimize the potential for splash, splatter, or other likely scenarios for accidental contact.
- Do not pour water into acid. Slowly add the acid to the water with stirring.
- Never empty carboys or drums of chemicals by means of air pressure. Use a tilting rack, a safety siphon, or a liquid pump.
- Use a mechanical aid or a pipette bulb for pipetting.
- Open bottles or carboys slowly and carefully and wear protective equipment to guard hands, face, and body from splashes, vapors, gases and fumes.
- Wipe drips from containers and bench tops. Be especially careful to wipe up visible residues of sodium hydroxide and potassium hydroxide from all surfaces. Skin contact with dry residue will result in burns.
Use a properly functioning lab fume hood when handling strong acids/ bases, or other chemicals that can form mists/ vapors.
At minimum, safety glasses, lab coat, long pants, and closed toed shoes are to be worn when entering laboratories having hazardous chemicals. When handling corrosive materials, chemical safety goggles (not safety glasses) provide the appropriate eye protection. Additionally:
- A face shield should be worn when splash or spray is foreseeable (in addition to goggles). An integrated face shield – splash goggle device can be used.
- When handling hazardous chemicals or contacting potentially contaminated surfaces, protective gloves are to be worn. For proper selection of glove material, review chemical MSDS or glove manufacturer’s reference materials for information.
- Additional protective clothing (i.e., apron, oversleeves) is appropriate where chemical contact with body and/or skin is foreseeable.
- Ensure secondary containment and segregation of incompatible chemicals. Also, follow any substance-specific storage guidance provided in MSDS documentation.
- Corrosives should never be stored above eye level.
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Neal Langerman - On line - 10/16/2008
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