Contact Lenses in a Chemical Environment
Many contact lens wearers have better results using PPE than wearers of eye glasses.
MORE than 34 million American contact lens users are working in laboratories and manufacturing, and they are doing so safely.8 Why people wear contact lenses rather than prescription glasses doesn't matter so much, as they do--and we, as safety professionals, have to ensure they can be protected.
It has been thought that contact lens should not be allowed in a chemical environment for several reasons:
* If chemicals were to be splashed into the eyes, contact lens would be difficult to remove and would hold chemicals against the cornea, causing further damage.
* If you were exposed to welding flash, the contact lens would fuse to your eyes.
* And for other, similar stated reasons.
These statements are not true. The 1978 edition of the NIOSH Pocket Guide to Chemicals Hazards recommended that workers not wear contact lenses. In the 2003 revised edition, that prohibition had been removed. In June of this year, NIOSH published Current Intelligence Bulletin 59: Contact Lens Use in a Chemical Environment8,3 allowing the use of contact lens for workers handling chemicals.
Even with this recommendation, there are some types of work where contact lenses should not be used at all. In the rest of the workplace, contact lens wearers will use whatever eye protection is required by the rest of the workforce.
Contact lens use should be part of an overall safety eyewear program, which would be included in your company's usage of personal protective equipment (PPE). The correct PPE would be determined by performing a hazard assessment, as per 29 CFR 1910. 132. (See reference 9 for further information on developing a hazard assessment.)
Part of the hazard assessment will be to review all chemicals used to see whether any reacts or interacts with contact lenses. If so, those uses and areas need to be noted and marked so employees and visitors will informed and can be properly protected. Here is a just a partial list of some chemicals that can react with contact lens or are restricted due to regulatory guidance, and why one should avoid contact lens use when handling them:
* 1,2-dibromo-3-chloropropane (DBCP): OSHA regulation8
* 4,4'-methylene dianiline: OSHA regulation8
* Ethyl alcohol: Study of absorption by Cerulli, et al. 19853
* Ethylene oxide: OSHA regulation8
* Isopropyl alcohol: Study of absorption by Cerulli, et al. 19853
* Methylene chloride: OSHA regulation8
NIOSH recommends that once the hazard assessment has been performed, the company should supply the necessary eye and face protection regardless of contact lens use. Many contact lens wearers have better results using PPE than wearers of eye glasses.
For example, look at what happens when the employee needs to use a full-face respirator. Once fit tested, a contact lens wearer needs only to put on the respirator, while the wearer of glasses needs to have special inserts made or to unscrew the temple pieces and "tape" the lens to the respirator facepiece, hoping it is placed correctly so he or she can see.
NIOSH's Recommendations
NIOSH recommends that workers be permitted to wear contact lenses when handling hazardous chemicals provided that the following safety guidelines are followed and that contact lenses are not banned by regulation or contraindicated by medical or industrial hygiene recommendations. However, contact lenses are not eye protective devices, and wearing them does not reduce the requirement for eye and face protection, the agency points out in Current Intelligence Bulletin 59, issued in June 2005. The agency noted that the recommendations address work with chemical hazards but not hazards from heat, radiation, or high-dust or high-particulate environments.
The guidelines suggest instituting a contact lens use policy with these steps included:
1. Conduct an eye injury hazard evaluation in the workplace that includes an assessment of the following:
* Chemical exposures (as required by OSHA's personal protective equipment standard [29 CFR 1910.132])
* Contact lens wear
* Appropriate eye and face protection for contact lens wearers
The eye injury hazard evaluation should be conducted by a competent, qualified person such as a certified industrial hygienist, a certified safety professional, or a toxicologist.
Information from the hazard evaluation should be provided to the examining occupational health nurse or occupational medicine physician.
The chemical exposure assessment for all workers should include, at a minimum, an evaluation of the properties of the chemicals in use--including concentration, permissible exposure limits, known eye irritant/injury properties, form of chemical (powder, liquid, or vapor), and possible routes of exposure. The assessment for contact lens wearers should include a review of the available information about lens absorption and adsorption for the class of chemicals in use and an account of the injury experience for the employer or industry, if known.
2. Provide suitable eye and face protection for all workers exposed to eye injury hazards, regardless of contact lens wear. Wearing contact lenses does not appear to require enhanced eye and face protection. For chemical vapor, liquid, or caustic dust hazards, the minimum protection consists of well-fitting nonvented or indirectly vented goggles or full-facepiece respirators. Close-fitting safety glasses with side protection provide limited chemical protection but do not prevent chemicals from bypassing the protection. Workers should wear face shields over other eye protection when needed for additional face protection, but they should not wear face shields instead of goggles or safety glasses?-regardless of contact lens wear.
3. Establish a written policy documenting general safety requirements for wearing contact lenses, including the eye and face protection required and any contact lens wear restrictions by work location or task. In addition to providing the general training required by the OSHA personal protective equipment standard [29 CFR 1910.132], provide training in employer policies on contact lens use, chemical exposures that may affect contact lens wearers, and first aid for contact lens wearers with a chemical exposure.
4. Comply with current OSHA regulations on contact lens wear and eye and face protection.
5. Notify workers and visitors about any defined areas where contact lenses are restricted.
6. Identify to supervisors all contact lens wearers working in chemical environments to ensure that the proper hazard assessment is completed and the proper eye protection and first aid equipment are available.
7. Train medical and first aid personnel in the removal of contact lenses and have the appropriate equipment available.
8. In the event of a chemical exposure, begin eye irrigation immediately and remove contact lenses as soon as practical. Do not delay irrigation while waiting for contact lens removal.
9. Instruct workers who wear contact lenses to remove the lenses at the first signs of eye redness or irritation. Contact lenses should be removed only in a clean environment after the workers have thoroughly washed their hands. Evaluate continued lens wear with the worker and the prescribing ophthalmologist or optometrist. Encourage workers to routinely inspect their contact lenses for damage and/or replace them regularly.
10. Evaluate restrictions on contact lens wear on a case-by-case basis. Take into account the visual requirements of individual workers wearing contact lenses as recommended by a qualified ophthalmologist or optometrist.
Training Considerations
Supervisors, first aid, and medical personnel should know which employees wear contact lens and should have appropriate training in the removal of contact lens in an emergency. However, the removal of the contact lens should not hold up any necessary first aid treatment, such as calling for an ambulance and flushing the eyes and face with water.
Even after allowing employees to use contact lenses, the workers should be instructed to remove the lenses at the first signs of redness or irritation. A form of Pink Eye known as Giant Papillary Conjunctivitis (GPC) occurs from chemicals, including some contact lens cleaners being absorbed into the lens and then desorbed onto the eye surface.7
Some employees need to wear contact lenses due to medical requirements from their vision care specialist. Others like contact lenses because they don't put pressure on their nose or decrease their peripheral vision, while still others use contact lenses because they are fashion-conscious.6
Safety professionals have to ensure that all employees work safely. By understanding the need to wear contact lenses and the hazards of the work environment, both the safety professional and contact lens wearers can be happy and be assured of working in a safe environment.
Sizing Issues Next for ANSI Z87.1 Standard
The American National Standard for Occupational and Educational Eye and Face Protection Devices, ANSI Z87.1-2003, is the most important consensus vision protection standard for U.S. industrial workplaces. It sets criteria for testing and use of spectacles, goggles, faceshields, and welding helmets.
As the standard is reviewed once again for reaffirmation, revision, or withdrawal in 2008, lens sizing is a subject being given "strong consideration," said Z87 Committee Chair Daniel Torgersen. The current edition of the standard does not require lateral protection, he pointed out.
Protective spectacle lenses must be at least 20 mm in height to meet "the only test in the Z87 standard that can be used to intimate some kind of vertical protection," which is the high-impact test, he said. But putting a lens of that size on a normal adult leaves much of the orbit uncovered, said Torgersen, who is vice president of information systems and special projects for Walman Optical Co. of Minneapolis and technical director for the Optical Laboratories Association.
"It's a terrific question," he added. Torgersen said the committee is strongly considering some specifications for minimum size. It sought anthropometric data and obtained useful data last spring from NIOSH.
Supplied by Z87 Committee member Jim Harris, P.E., of NIOSH's Division of Safety Research (Morgantown, W.Va.), the data show the maximum height, width, and depth of the approximate soft-tissue eye area on headforms from eight data sets, including the Alderson 50th percentile and a set developed in the late 1990s by the National Operating Committee on Standards for Athletic Equipment. NOCSAE's is supported by lots of data and is the best documented, Harris said.
What is striking about the data sets is that the maximum heights for all eight exceed 20 mm. The maximum height of the largest, the Alderson 95th percentile, is 41.5 mm--twice as large. This indicates using the Alderson 95th percentile to create eyewear lenses would be "the safest bet," Torgersen said. While even this wouldn't protect the largest eyes, it would protect wearers' eyes to the greatest extent possible, he explained.
Lens size is an issue to manufacturers, of course, including some who want the Z87.1 standard to be broader so that it takes into account the shape and size of typical Asian and African-American faces. The standard is based on a 50th percentile adult Caucasian male headform.
"At the time, 25 years ago and earlier, the workforce of the U.S.--and probably North America and Europe, too--was dominated by males and dominated by Caucasian males," said Ron Desjardins, a North Safety Products eyewear product manager who is a member of ISEA's eyewear group. "As you know, the workforce is changing; the industrial workforce is changing. Those who are working are less and less Caucasian males and more and more female, African-American, and Asian."
Many manufacturers of protective eyewear have tried to accommodate these new faces with adjustable features, larger sizes, or models that are shipped with bridge pieces of different sizes. Small, medium-sized, and large eyewear sizes might be the way to go, Desjardins said. "At a bare minimum, you need two sizes, and ideally three, to fit a broad range of the population," he said.
The data sets gathered by NIOSH's Harris do not take Asian and African-American faces into account, he said.
The Z87 Committee's next two meetings are set in Orlando in December 2005 and then in Baltimore next spring. Torgersen and Harris said the sizing issue is ripe for discussion when members gather in Orlando.
"The last time, all the energy was put into the prescription lens testing setup. It took all the energy of the committee deciding that," Harris said.
The committee's secretariat is ISEA; for information, contact ISEA Technical Director Janice Bradley or Technical Projects Coordinator Cristine Fargo at 703-525-1695.
References
1. Contact Lens Council, www.contactlenscouncil.org.
2. "Contact Lens Wear," American Welding Society, 1995. www.aws.org/technical/facts/FACT-12.PDF.
3. "Current Intelligence Bulletin 59: Contact Lens Use in a Chemical Environment," NIOSH, 2005. www.cdc.gov/niosh/docs/2005-139/.
4. "Eye Protection in the Workplace," OSHA, 1993. www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=FACT_SHEETS&p_id=142.
5. "Medical Society Releases Guideline on Contact Lens Use in the Workplace," Workindex.com, 2003, www.workindex.com/editorial/benefit/ben0307-h-01.asp.
6. Segal, Eileen B., "Contact Lenses And Chemicals," Chemical Health & Safety, American Chemical Society, May/June 1997. http://pubs.acs.org/hotartcl/chas/97/mayjun/con.html.
7. Steen-Hall Eye Institute, Giant Papillary Conjunctivitis, 2005. http://www.steen-hall.com/gpc.html.
8. "The Use of Contact Lenses in an Industrial Environment," American College of Occupational and Environmental, 2003. www.acoem.org/position/statements.asp?CATA_ID=58.
9. Weissman, Barry, "Hazard Assessment, Eye Protection, and You," Occupational Health & Safety, October 2004. www.ohsonline.com/articles/44779/
This article appeared in the October 2005 issue of Occupational Health & Safety.
This article originally appeared in the October 2005 issue of Occupational Health & Safety.