Safety

Last modified on 05/16/02

Information on biosafety levels and equipment is located in the Laws and Regulations section. Click here.

Occupational Health

"Principal requirements for an institutional occupational health program are outlined in the Guide for the Care and Use of Laboratory Animals. .. Thus, the institution must base their health program on an assessment of the risks present in its particular animal research program, including those in cagewashing and other support activities. Basic elements of any health program, however, should provide:

1. a pre-employment medical evaluation and history;

2. immunization against tetanus;

3. detailed training on how to perform required procedures safely;

4. instruction in personal hygiene, zoonoses, and precautions for pregnant women and others at risk;

5. protective clothing and devices;

6. instruction in first aid procedures appropriate to potential hazards;

7. and access to medical attention for the treatment of animal bites, scratches, allergies and other job-related injuries or illnesses.

When there is risk of exposure to rabies through the use of random-source dogs and cats and certain wildlife species, the institution should offer pre-exposure immunization, and should regularly schedule tuberculin testing for all personnel exposed to nonhuman primates. The institution should have precautions in place and a zoonosis surveillance mechanism established when work involves exposure to nonhuman primates and species likely to harbor the causative agents of diseases such as Q fever, tularemia, hantavirus pulmonary syndrome, and plague. When research involves infectious diseases, such as hepatitis B, for which there are safe and effective vaccines, the use of prophylactic immunizations should also be considered. A health program is required not only for persons having "frequent contact with animals," but for all "personnel who work in laboratory animal facilities." These include not only animal caretakers, technicians, students, volunteers, investigators, and veterinarians but facilities maintenance engineers, housekeepers, security, and other staff. OLAW recommends that the foregoing phrases be interpreted in the context of the potential risks to which the persons are exposed..."{3755}

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Radiation Safety

Radiation damages tissues by ionizing molecules, including DNA. Beta particles are electrons that have a very short travel range in air, about a foot. Some beta emitters (i.e. ³²P) are powerful and require shielding, while others (¹⁴C, ³⁵S and ³³P) are weak emitters. ¹²⁵I is an X-ray and gamma emitter; gamma rays penetrate more than beta particles. Gamma rays originate in the nucleus, whereas X-rays originate outside the nucleus. Iodine and sulfur are also volatile and must be handled in a fume hood.{4173}

Most radiological chemicals used in healthcare and molecular biology are used in very low amounts, but there are no exposure thresholds for the determination of detrimental biological effects. The goal is to keep exposure "as low as reasonably possible" (ALARA).{4173}

Measures of radioactivity start with the Curie, which is 3.7 x 10¹⁰ disintegrations per second. Amounts used in animal studies typically range from 0.07-0.8 mCi per gram body weight. In molecular biology experiments, amounts ranging from 0.1-5mCi are typical. A Becquerel (Bq) is one disintegration per second, so 1mCi=37MBq.{4173}

The dose of radiation is derived from exposure to sources external to the body and from any radioisotopes that have been ingested, inhaled, or otherwise absorbed into the body.

Annual federal radiation dose limits{4173}:

Target	Dose limit, mrem
Whole body	5,000
Extremities	50,000
Eye	15,000
Skin	50,000

There are 3 "golden rules" of radiation safety: (1) shorter exposure time, smaller the total dose; (2) maintain a distance wherever possible, as exposure rate drops as the inverse square of the distance; (3) use shielding with powerful beta emitters such as ³²P; use lead shielding with large amounts of ¹²⁵I. The average American receives about 300mrem (a measure of radiation energy absorbed in a target material) per year, mostly from radon. Annual limits range from 5,000 mrem (whole body) to 50,000mrem (skin).{4173} According to an article in CTLAS, the National Council of Radiation Protection limit on annual exposure from X-ray equipment in unrestricted areas is 100mrem per year{4486}.

Radiation safety protocols may include: (1) used only by experienced personnel; (2) avoid skin contact and use PPE such as lab coats, masks and safety glasses; (3) use a Geiger-Müller detector frequently during the procedure, supplemented with wipe testing; (4) survey procedure rooms following the conclusion of the experiment; (5) segregate disposable waste from normal waste.{4173}

GM counters must be used properly. There are settings on the dial from "1X" to "1000X" to indicate how much the readout is being multiplied; always start at 1X for the most sensitive measurement. One must know what the normal background counts are, and calibrate by checking a known source. Wipe testing involves wiping a 4x4 inch area with a wet filter paper or swab and placing in scintillation fluid for counting. Cleaning contaminated surfaces can be done with cleaning solutions, preferably foam that minimizes liquid use.{4173}

Radioactive waste is handled with the following procedures: (1) segregate radioactive from non-radioactive; (2) segregate biological from non-biological; (3) do not mix dry with liquid wastes; (4) if possible, use "decay-in-storage", i.e. holding waste for 10 or more half-lives before disposal (at this point it can be handled as regular waste); (5) pretreat radioactive carcasses, i.e. with vermiculite and lime to limit decomposition and hold fluids; (6) use a cold room or marked freezer for short-term safekeeping of carcasses; (7) usually quarterly or semi-annual pickups are used; (8) radioactive disposal logs must be maintained by researchers. Animals such as dogs or NHPs that may remain radioactive for months must be kept separate from the colony and monitored carefully. Some communities allow disposal of radioactive materials such as urine and feces into the sewer system.{4173}

Radiation safety is controlled by the US Nuclear Regulatory Commission, equivalent state agencies, and by institutional policy. A Radioactive Materials License allows the institution to possess and use radioactive material. It mandates radiation safety training, possibly annual retraining and other factors.{4173}

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Exposure Limits

Anesthetic gases

Nitrous oxide

Formaldehyde

Gases commonly found in rodent cages
Ammonia
CO₂

Noise

Anesthetic gases

An excellent paper is available on the OSHA web site at http://www.osha.gov/dts/osta/anestheticgases/anesthetic_gases.html#C1

Cooper et al wanted to know if using isoflurane to anesthetize mice in a common laminar-flow work bench presented undue exposure risks to personnel. They found that use of a smallish chamber (~1 liter) with a tight-fitting lid resulted in peaks of gas exposure at the worker's breathing level that averaged 1.5 ppm. Use of a large chamber (4l) with a tight lid resulted in peak exposure of 42ppm. Use of a nose cone to maintain anesthesia gave peaks of 35ppm. If they switched to a class IIA biosafety cabinet the levels remained below about 5ppm for the large chamber. OSHA has not set exposure limits for any of the common anesthetics. NIOSH has set limits for halothane and methoxyflurane of 2ppm as a short-term exposure limit (STEL), and the ACGIH recommends an 8-hr time weighted average (TWA) of 50ppm for halothane. Although there is evidence for hepatotoxicity from halothane (due to antibodies to metabolites damaging the liver) and nephrotoxicity from methoxyflurane (from defluorination and renal excretion), there is no evidence of toxicity from isoflurane. However, antibodies to isoflurane metabolites can cross-react with those to halothane.{4019}

Nitrous oxide (N₂O)

	OSHA PEL: OSHA does not currently regulate nitrous oxide
	NIOSH REL: NIOSH has established a recommended exposure limit (REL) for nitrous oxide of 25 parts per million (ppm) parts of air (45 milligrams per cubic meter (mg/m³) as a time-weighted average (TWA) for the duration of the exposure
	ACGIH TLV: ACGIH has assigned nitrous oxide a threshold limit value (TLV) of 50 ppm (90 mg/m³) as a TWA for a normal 8-hour workday and a 40-hour workweek

Health hazards to humans: Patients exposed to a 50:50 mixture of nitrous oxide:oxygen for prolonged periods to induce continuous sedation developed bone marrow depression and granulocytopenia. Although most patients recover, several deaths from aplastic anemia have been reported. Long-term occupational exposure (dentists, dental assistants) has been associated with numbness, difficulty in concentrating, paresthesias, and impairment of equilibrium. Epidemiological studies, primarily of operating room personnel, have shown increased risks of spontaneous abortion, premature delivery, and involuntary infertility among these occupationally exposed populations.

Determination of a worker's exposure to airborne nitrous oxide can be made using one of the following techniques: 1) a Landauer Passive Dosimeter badge, which can be used for a minimum sampling duration of 1 hour (maximum duration 40 hours). Analysis is performed by the manufacturer of the badge as described in the OSHA Computerized Information System, or 2) an ambient air or bag sample with a minimum collection volume of two spectrophotometer cell volumes. Analysis is conducted using a long-pathlength portable infrared spectrophotometer as described in NIOSH Method No. 6600.

(from http://www.osha-slc.gov/SLTC/healthguidelines/nitrousoxide/recognition.html)

Activated charcoal canisters will effectively adsorb the vapors of halogenated anesthetics but not N₂O. (from the OSHA site listed at the beginning of this section)

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Formaldehyde

A good site for formaldehyde and formalin regulatory information is at http://www.osha.gov/SLTC/formaldehyde/index.html. OSHA's eight-hour, time-weighted average permissible exposure limit (PEL) is 0.75ppm and the 15 minute, short-term exposure limit (STEL) is 2.0ppm. Side effects associated with formaldehyde exposure include upper respiratory tract irritation, allergic contact dermatitis, nasal and lung cancer, eczema, and lacrimation.{3782}

According to the MSDS sheet for formaldehyde, the following airborne exposure limits apply:

OSHA Permissible Exposure Limit (PEL)

	0.75 ppm (TWA)= maximum exposure in 8 hours
	2 ppm (STEL)= maximum exposure in 15 minutes
	0.5 ppm (TWA) action level for formaldehyde in an 8-hour period. According to the OSHA Standard, "If the last monitoring results reveal employee exposure at or above the action level, the employer shall repeat monitoring of the employees at least every 6 months."

Further portions of the standard follow:

..1910.1048(h)(1)(i)

All contact of the eyes and skin with liquids containing 1 percent or more formaldehyde shall be prevented by the use of chemical protective clothing made of material impervious to formaldehyde and the use of other personal protective equipment, such as goggles and face shields, as appropriate to the operation.

..1910.1048(i)(3)

If there is any possibility that an employee's eyes may be splashed with solutions containing 0.1 percent or greater formaldehyde, the employer shall provide acceptable eyewash facilities within the immediate work area for emergency use.

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