4th National Symposium on Biosafety

Face Protection in Animal Research

Martin S. Favero, PhD
Director, Hospital Infections Program
Centers for Disease Control and Prevention
1600 Clifton Road MS A-07
Atlanta, GA 30333
404-639-6401

I will cover very briefly the relationship between laboratory and animal biosafety levels and the impact of protective garb, particularly, protection of the face. Specifically, I will be considering protection of the worker and not what the surgeon needs to wear to protect the animal. That is a different subject. I will be discussing respiratory protection as well. It has been my observation that when one considers the type of strategy, to control environmental transmission within an acute care hospital, a laboratory, or an animal facility, that the degree of conservatism goes in the direction of the animal facility. This is a subject that we discussed in the workshop relative to the types of germicides that are used. This is not a significant subject in acute care hospitals, a little more significant in a laboratory setting; but in an animal facility, the reality for the occurrence of environmental transmission is a major part of the strategy because it can and does occur.

Infections are not transmitted off the floor very often in a hospital. That's not true in an animal facility. The type of strategy, in terms of conservatism, also spills over when one considers protection of the worker in terms of face protection, the use of goggles, shields and relative to respiratory protection. This is the skeleton of biosafety levels, and I am referring specifically to animal facilities described in the CDC/NIH manual that you have in your handout materials. The second part of that book deals with the animal facilities. It discusses agents and their levels, practices and safety equipment. Primary barriers in this section of the manual deal with protective equipment. There are not large sections written about face protection. If you look in the other resource publication, (the draft Guide for the Care and Use of Laboratory Animals), there are not too many words about face protection either. I could not find any document that has specifications for face protection in the context of face shields, eye protection, or goggles. For respiratory protection, there are specifications thatI will discuss later, but most strategies are going to depend on common sense judgment. It is primarily in biosafety levels 1 and 2 where one has to make those judgments. As one goes to biosafety level 3 in an animal facility and especially 4, the risk for exposure to mucus membranes of the face and respiratory protection are basically designed out.

If we look at animal biosafety level 1, these agents are not known to cause diseases in healthy humans. The script there for primary barriers is no special clothing, face, or respiratory protection. So, it is a matter of judgment. If one is taking care of ordinary animals and there might be a problem with spitting and scratching, maybe safety goggles would be called for. Mostly, we are talking about biosafety level 2, where animals may harbor agents associatedwith human disease and the hazards may be associated with percutaneous exposure, ingestion, or mucus membrane exposure. An example would be the hepatitis viruses. We are not talking about airborne transmission. We are talking about direct contact. Depending on the type of animal, there clearly could be splashing and spattering of droplets through the air that might end up in the mucus membranes of the eyes, mouth and the nose. For example, with the hepatitis viruses, it was not uncommon years ago, before the science and art of biosafety got implemented into primate laboratories, that the animal handlers of animals used for Hepatitis A or B research or animals that were indigenously infected with those viruses, were all seropositive for antibodies to these agents. The primary barriers; laboratory coats, gowns, gloves, and face and respiratory protection are used as needed.

In this instance, face protection means sturdy face shields or perhaps safety glasses. For respiratory protection, the principle is, if there is an agent that is known to be transmitted by the airborne route, then respiratory protection must be implemented. There are some definite principles to adhere to. It is not just putting on a wraparound surgical mask. Surgical masks are for doing surgery. Respiratory protection means that respirators ought to be used. In biosafety level 3 facilities there are indigenous or exotic agents with a potential for aerosol transmission and the disease may have serious health effects. Some of the agents include: tularemia, mycobacterium tuberculosis, the hemorrhagic fever virus, yellow fever virus, to name a few.

The primary barriers are engineering controls; biological safety cabinets, ventilation, containment, protective laboratory clothing, (such as wrap around gowns, scrub suits and so forth). This is the first time in this CDC/NIH manual where there are more descriptive parts. Specific mention is made about goggles, masks or face shields, and respiratory protection when aerosols cannot be safety contained. Under ordinary circumstances, the types of procedures that are done with these animals, are done within a barrier. In other words, the risk is supposedly designed out. Often times Murphy's law comes into play and one cannot always assume that the design out phase is working and it might be one's judgment to actually employ a particular respirator. Animal biosafety level 4, which is practiced in very few laboratories in this country, indeed the world, use dangerous exotic agents which pose an extraordinarily high risk of life threatening disease. They are transmitted by aerosol, contact, or by unknown means. These include Marburg, Lassa virus, ebola, Russian spring and summer encephalitis virus. The strategy is to use maximum containment or partial containment with full body air supply-positive pressure personnel suits. Goggles, face shields, and whether one is going to wear a particular respirator, are not even applicable here because the degree of containment and the degree of protection are several orders of magnitude greater and respirator type is literally designed out.

In acute care hospitals, there has been an exercise for the last four or five years about protection of health care workers from exposure to mycobacterium tuberculosis. That debate has genrated a lot of knowledge on the part of infectious disease specialists. Industrial hygienists have had knowledge for a long time, and although these two groups tended to be polarized, there was a meeting of the minds. Any worker dealing with animals for which there is a risk of true airborne transmission (that is, the generation of viable particularities in the five to ten micron range) needs to wear face protection, which is simply protecting mucus membranes, eye, nose, mouth, some sort of respiratory protective device. The new NIOSH classification system for respirator is N95, N99 and N99.9 with the efficiency of retaining 0.3 micron particle. In summary, face protection with goggles, safety glasses or visors can prevent eye and mucus membrane exposures. Respirators should be used when caring for animals with infections known to be transmitted by the airborne route.

Face Protection in Animal Research Breakout Session
Rapporteur: Robert J. Mullan, MD Medical Officer NIOSH/CDC 1600 Clifton Road, F-40 Atlanta, GA 30333 404-639-2377

By far the most controversial aspect of my work with occupational tuberculosis has been the use of respiratory protection in protecting workers. Our break-out group was marked by a very lively discussion about issues surrounding the use of such protection in workers, and I'd like to spend a little bit of time this morning looking at some of those issues.

First of all there, was a great amount of confusion about the difference between "masks" and "respirators". We at CDC have a special way of defining these two items and I'll take a little bit of time this explain this. We also spent some time talking about practical issues concerning the simultaneous use of respirators and eye wear. We'll also take a look at that.

In one of the afternoon discussions yesterday Dr. Bennett talked about key concepts involved in communication to workers and others. One of the concepts that he stressed was that for effective communication to take place, everybody has to be talking from the same dictionary. Well, I think it's clear that, at least in terms of respiratory protection, we're not talking from the same dictionary. So this morning we'll talk a little bit about how we define these terms, masks and respirators so that we can talk from the same dictionary.

"Masks" are an FDA-approved device, and we're generally referring to a surgical mask. These masks are designed for protection of patients (or in your case animals). They are not designed or meant to be used for the protection of workers. These masks are designed therefore to protect mostly against splashes of potentially infectious materials. They are not designed for protection against aerosol exposures.

Respirators, on the other hand, are NIOSH-certified and are designed for the protection of workers. They are designed to protect against aerosols. So, if you're concerned transmission of infectious aerosols, what you need is a respirator and not a mask.

There were also a number of questions about the role of OSHA and some complaints. OSHA requires you to have a respiratory protection program in place if you have to put a respirator on a worker for the purpose of protecting the worker against aerosols. I think there's a great deal of confusion on that point.

I think its safe to say in at least one of the documents I examined last night (the CDC/NIH Biosafety in Microbiological and Biomedical Laboratories) there might be some concern that we, as guidelines writers may not have been totally clear in how we wrote up some of the recommendations. This goes to another key concept in communication that was discussed yesterday afternoon: that communication involves not only the conveyance of the message but also ensuring that that message is fully received and understood by the audience. I think we, as guidelines writers, probably need to take a few clues from that presentation yesterday afternoon and work diligently to make sure that the messages that we're trying to convey in these various guidelines are received and understood.

There were a number of miscellaneous concerns discussed during the course of our work yesterday afternoon. In the case of eyewear, there were questions about the concurrent use of contact lenses. The answers revolved around making sure that if you allow our workers to wear contacts at the same time they are wearing protective eyewear, you should be able to prove to OSHA that this will not cause a risk to workers. Furthermore, if you're wearing contact lenses in an area where there may be other chemical toxic exposures, you have to be concerned that these various chemicals may cause distortion or breakdown of the contact lens itself. A major concern for our participants is the problem of fogging of eyewear. There was a fairly lengthy discussion about potential remedies. Most people thought that there were really no good remedies on the market, so this remains a problem. Perhaps the way to address this problem is to be very careful about how you choose your eyewear. There are a lot of designs out there. Some of them work better then others in preventing fogging.

A problem that has arisen with the use of respirators is allergic reactions. There are two mechanisms involved. First, many of the currently available respirators use a latex seal around the edge of the mask to make sure that the mask fits tightly on the face. In those products that use natural rubber latex, there is a risk of developing an allergy to natural rubber latex following use of these respirators. This problem can be minimized by choosing respirators that use some artificial compound for the face seal. A similar problem evolves from aerosol danders from the various laboratory animals. Those danders become lodged around the edge of the respirator and they then become contact allergens. This is a problem that we had not heard about and certainly one that requires investigation.

Respirators may be used in your animal-care facilities for more than protection against infectious diseases. There are chemical explosions which occur during cage cleaning and other procedures involving sterilization and so forth. You have to be careful that the respirator you choose will protect you against those situations as well. Manufacturers are usually fairly good with helping you out with that problem.

The last and perennial question involves workers with beards. According to OSHA, workers with beards cannot be adequately protected with a negative-pressure respirator. There are ways to get around this without making the worker shave his beard. There are respirators, such as loose-fitting, powered air-supply respirators, that don't require a tight face seal. Those would be appropriate for use with these individuals.

I'd like to give you my phone number. It is clear that respiratory protection is still a contentious problem, and a lot of you are just beginning to look at this issue. If you do have questions you can call me at this number [404-639-1533] and I'll be glad to assist you or direct you to further resources.

Last I'd just like to mention that the National Institute for Occupational Safety and Health (NIOSH) has recently undergone a change in the way we certify respirators. There was a lot of talk in my group yesterday about dust-mist and HEPA (high-efficiency particulate air) respirators. Terminology has all changed. We now talk about N-, R, and P-series respirators. Each of these various N-, R, and P-series respirators are also available in three levels of efficiency: 95 percent, 99 percent, and what we call 100 (which has an efficiency of at least 99.97 percent). All of these respirators have been tested with a particle size of 0.3 microns, which is the most penetrating size particle. The one that you are likely to be most interested is the N-95 respirator. It is the least complicated of these disposable respirators and will protect you in any situation where you are concerned about tuberculosis. These respirators are in general much cheaper then what we had under the old certification process. In the past we've recommended HEPA respirators. Those of you who have used HEPA respirators know that they are not cheap. They run about $6.00 each. The N-95 respirator costs about 60 cents. So there is a considerable cost savings involved.

We will also be upgrading other aspects of our respirator certification process. For instance, NIOSH will be looking at fit testing. So stay tuned.

Office of Health and Safety, Centers for Disease Control and Prevention, 1600 Clifton Road N.E., Mail Stop F05 Atlanta, Georgia 30333, USA Last Modified: 1/2/97
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Face Protection in Animal Research