Chemotherapeutics on Rise; so are Health Risks


Use of cytotoxic drugs are believed on the rise, officials report, consequently, so are the potential adverse health risks to veterinarians handling these chemicals.

Use of cytotoxic drugs are believed on the rise, officials report, consequently, so are the potential adverse health risks to veterinarians handling these chemicals.

Take serious precautions when administering cytotoxic drugs, experts say. Some of these drugs rank as the most hazardous used in veterinary hospitals.

While chemotherapies are saving and prolonging patients' lives, veterinarians need to have well-rehearsed plans of response in the event of a mishap and stay well aware of the potential long-term health risks in handling these chemicals, experts say.

Veterinary oncologist Michael Lucroy, DVM, MS, diplomate of ACVIM, sums it up this way: The more chemotherapeutics used, the greater the risk of a spill or other accident involving the veterinarian, technician and/or patient.

Of all the chemical dangers lurking in a veterinary hospital, the cytotoxic drugs are believed to be some of the most dangerous, says Dr. Diane McKelvey, author of "Safety Handbook for Veterinary Hospital Staff" (AAHA Press).

McKelvey states that in one reported case a simple needlestick with mitomycin-C has reportedly caused the eventual loss of function to the hand. Doxorubicin's toxicity on contact with skin is well documented and can result in a catastrophic slough that could result in amputation or even euthanasia of an affected patient.

Lucroy, an associate professor of the Oklahoma State University's College of Veterinary Medicine and the Kerr Foundation for Biomedical Laser and Biophotonics Research, says, "Of all places to work, the veterinary practice is probably one of the most dangerous. We have radiation hazards, and many other chemical hazards. Ethylene oxide is used to sterilize instruments, and is a carcinogen. A lot of the disinfectants are pretty dangerous chemicals. So, we are around a lot of pretty bad stuff."

Table 1

Increasing use

In veterinary medicine, oncology is hot.

While the American Animal Hospital Association wasn't tracking statistics to support the industry-wide belief that oncology procedures are on the rise, a 2000 DVM Newsmagazine survey notes that about 24 percent of practitioners planned on developing greater expertise or expanding services in the years ahead.

"More of it (chemotherapy) seems to be going on in the coastal areas of the country," Lucroy explains. "More cancer therapies are available today, and it's not just the boarded oncologists who are working on these cases."

More often progressive small animal practices are definitely treating lymphoma, and sometimes osteosarcomas, before referring to a boarded specialist in oncology, especially practices with more affluent clientele who can afford some of these expensive procedures.

In essence, the more use, the greater the risks, Lucroy adds.

Red death

If you leak doxorubicin on your patient, first consult your lawyer and then attempt to treat the patient; that, at least, is the way Lucroy teaches it in veterinary school to drive home the point that this chemical can be catastrophic if a leak occurs during administration.

Also, the risk to handlers is very real.

Lucroy explains that the drug is a vesicant. In other words, its mode of action is to kill cancer cells; once the cell is dead, it moves to the next cell.

"So, if this stuff gets outside the blood vessel it has the capacity to cause tremendous tissue damage. There is a reason this compound is nicknamed 'red death', and it can cause a catastrophic slough if extravested."

Lucroy advises all practitioners to remember the five "Rs" of chemotherapeutic use:

  • Right patient

  • Right drug

  • Right dose

  • Right time

  • Right route

There are additional risks to people exposed to these compounds, as well.

"I mean you may be sending home enough drug to kill a small child, so those child-proof lids are paramount," he says.

Take precautions

Exposure for veterinarians and technicians would likely come during handling and preparation of chemotherapeutic drugs.

Lucroy recommends that safety starts with storage and continues through the administration and eventual elimination of the drug by the animal through defecation.

Storage is a critical area of concern, Lucroy says. In fact, many veterinary hospitals store drugs in the hospital refrigerator along with lunches and everything else brought in. He says it is a "no-no", especially with cytotoxic drugs.

An eyewash station is critical to protect oneself from an accidental spill or splash, officials say. When working with cytotoxic drugs, OSHA calls for a spill kit.

"They definitely need to be segregated from the rest of the inventory. If you limit access to these drugs, you would bring the risks down of potentially exposing the veterinary staff if accidentally dropping a vial.

"You definitely do not want to put them in a place where they will likely get broken or roll off a shelf. And you definitely don't want general access to these drugs because of their danger potential," he adds.

Most chemotherapeutic agents should be prepared under a class II biological safety cabinet or use a pharmacy that has the equipment.

"The alternative is to mix up drugs on the countertop, and obviously the risks go up quite a bit, they could conceivably contaminate themselves and the entire work area," he says.

Going airborne

Contact with the skin is not the only risk for veterinarians either.

The Occupational Safety and Health Administration (OSHA) says that monitoring efforts for cytotoxic drugs have detected measurable air levels when exhaust biological safety cabinets were not used for preparation. Studies have shown elevated concentrations of both cyclophosphamide and fluorocil.

OSHA says that the main routes of exposure to any hazardous drug are inhalation of dusts or aerosols, dermal absorption and ingestion. The main cause of ingestion is from contamination from food or cigarettes, OSHA adds.

Be prepared

While spills are not as common as one might think, Lucroy says, they still happen, and it's important for practitioners to be prepared.

Lucroy recommends becoming very familiar with the OSHA's Technical Manual. There is an extensive section on controlling occupational exposure to hazardous drugs.

"Certainly, if you drop a vial accidentally, you could have a good volume of drug in the environment. So, it is recommended that wherever you prepare or administer drugs you have a chemotherapy spill kit.

OSHA guidelines for spill kits include personal protection equipment, a plastic scoop and brush for shards, items like a sharps container, some large clearly labeled plastic bags to put all your junk in when you are done. OSHA also recommends a means to control liquid spills by including absorbable pads or a powder that turns to a gel instantly.

"If you get it on you, you should wash yourself thoroughly with soap and water, and seek medical attention depending on the toxicity of the agent you come in contact with. If you get it on your personal protection equipment, you should get out of those immediately and put on new ones.

OSHA guidelines indicate that victims of hazardous drug spills should see a healthcare professional just to be checked out.

There are also very strict rules on recordkeeping, Lucroy explains. Following a spill of a hazardous drug, the hospital needs to maintain these medical records for the duration of employment plus another 30 years.

OSHA guidelines state that any employees who come in contact with these hazardous materials get a pre-employment health exam. Periodic health screenings and then a post-employment health exam are also recommended.

Lucroy says the recordkeeping requirement helps document exposures and would ultimately protect the practice from future liability.

Risk data hard to find

While there isn't much risk data on occupational exposures to some of these drugs, studies have shown that people who handle these drugs without protective measures have measurable levels of the drug or metabolites in their urine.

"In human oncology nurses and pharmacy staff members, they have detected chromosome aberrations and lymphocytes from peripheral blood. Studies have also listed risks to women in the workplace when handling chemotherapy drugs. The studies have shown a higher rate of pre-term labor or miscarriage, and maybe an increased risk for birth defects.

"The problems with a lot of these studies," Lucroy explains, "is they don't have a lot of people in there and they were often retrospective. So, it is tough to really know the true risks. But we know from our experience with people and experimental animals going through chemotherapy that they can develop a second malignancy that is probably induced by the chemotherapy," he adds.

"These drugs are mutagenic; in other words, they can change DNA. Most drugs that are mutagenic are also carcinogenic."

Lucroy says, "I think some of the places I have worked, it is just amazing that no one died during that time or suffered permanent health damage. Who knows what can happen down the road."

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