Sterilant gas monitoring

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Sterilant gas monitoring is the detection of hazardous gases used by health care and other facilities to sterilize medical supplies that cannot be sterilized by heat or steam methods. [1] The current FDA approved sterilant gases are ethylene oxide, [2] hydrogen peroxide [3] and ozone. [4] Other liquid sterilants, such as peracetic acid, may also be used for sterilization and may raise similar occupational health issues. [5] Sterilization means the complete destruction of all biological life (including viruses and sporoidal forms of bacteria), and sterilization efficacy is typically considered adequate if less than one in a million microbes remain viable.

Contents

Hazards of sterilant gases

Since sterilant gases are selected to destroy a wide range of biological life forms, any gas which is suitable for sterilization will present a hazard to personnel exposed to it. NIOSH's IDLH (immediately dangerous to life and health) values for the three sterilant gases are 800 ppm (ethylene oxide), 75 ppm (hydrogen peroxide) and 5 ppm (ozone). [6] For comparison, the IDLH of cyanide gas (hydrogen cyanide) is 50 ppm. The OSHA PEL (permissible exposure limit) will be considerably lower than this; 1 ppm for ethylene oxide, or 5 ppm for a 15 minute short-term exposure limit. [7] Thus exposure to even low levels of sterilant gas should not be treated casually and most facilities go to great lengths to adequately protect their employees. In addition to toxicity, ethylene oxide is flammable (from above 3%) [1] and ozone is damaging to equipment not designed to resist it.

Sterilizer manufacturers go to great lengths to make their products as safe as possible but, as with any mechanical device, they can and sometimes do fail and leaks have been reported. [8] The odor threshold for these gases is above the PELs and for ethylene oxide it is 500 ppm, approaching that of the IDLH. [1] Odor is thus inadequate as a monitoring technique. Continuous gas monitors are used as part of an overall safety program to provide a prompt alert to nearby workers in the event that there is a leak of the sterilant gas. [5] [9]

Monitoring equipment

The monitor alarms are typically set to warn if the concentrations exceed the OSHA permissible exposure limits (PELs), 1.0 ppm for ethylene oxide [10] and 1.0 and 0.1 ppm for hydrogen peroxide and ozone respectively. [11] The PELs are calculated as 8 hour time weighted average values (i.e. the average exposure over a typical shift).

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<span class="mw-page-title-main">Hydrogen peroxide</span> Chemical compound

Hydrogen peroxide is a chemical compound with the formula H2O2. In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution in water for consumer use, and in higher concentrations for industrial use. Concentrated hydrogen peroxide, or "high-test peroxide", decomposes explosively when heated and has been used both as a monopropellant and an oxidizer in rocketry.

<span class="mw-page-title-main">Hydrazine</span> Colorless flammable liquid with an ammonia-like odor

Hydrazine is an inorganic compound with the chemical formula N2H4. It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly toxic unless handled in solution as, for example, hydrazine hydrate.

<span class="mw-page-title-main">Nitric oxide</span> Colorless gas with the formula NO

Nitric oxide is a colorless gas with the formula NO. It is one of the principal oxides of nitrogen. Nitric oxide is a free radical: it has an unpaired electron, which is sometimes denoted by a dot in its chemical formula. Nitric oxide is also a heteronuclear diatomic molecule, a class of molecules whose study spawned early modern theories of chemical bonding. The dimer is the main form in the liquid phase.

Bromomethane, commonly known as methyl bromide, is an organobromine compound with formula CH3Br. This colorless, odorless, nonflammable gas is produced both industrially and biologically. It has a tetrahedral shape and it is a recognized ozone-depleting chemical. It was used extensively as a pesticide until being phased out by most countries in the early 2000s.

<span class="mw-page-title-main">Ethylene oxide</span> Cyclic compound (C2H4O)

Ethylene oxide is an organic compound with the formula C2H4O. It is a cyclic ether and the simplest epoxide: a three-membered ring consisting of one oxygen atom and two carbon atoms. Ethylene oxide is a colorless and flammable gas with a faintly sweet odor. Because it is a strained ring, ethylene oxide easily participates in a number of addition reactions that result in ring-opening. Ethylene oxide is isomeric with acetaldehyde and with vinyl alcohol. Ethylene oxide is industrially produced by oxidation of ethylene in the presence of a silver catalyst.

<span class="mw-page-title-main">Sterilization (microbiology)</span> Process that eliminates all biological agents on an object or in a volume

Sterilization refers to any process that removes, kills, or deactivates all forms of life and other biological agents present in or on a specific surface, object, or fluid. Sterilization can be achieved through various means, including heat, chemicals, irradiation, high pressure, and filtration. Sterilization is distinct from disinfection, sanitization, and pasteurization, in that those methods reduce rather than eliminate all forms of life and biological agents present. After sterilization, an object is referred to as being sterile or aseptic.

<span class="mw-page-title-main">Disinfectant</span> Antimicrobial agent that inactivates or destroys microbes

A disinfectant is a chemical substance or compound used to inactivate or destroy microorganisms on inert surfaces. Disinfection does not necessarily kill all microorganisms, especially resistant bacterial spores; it is less effective than sterilization, which is an extreme physical or chemical process that kills all types of life. Disinfectants are generally distinguished from other antimicrobial agents such as antibiotics, which destroy microorganisms within the body, and antiseptics, which destroy microorganisms on living tissue. Disinfectants are also different from biocides—the latter are intended to destroy all forms of life, not just microorganisms. Disinfectants work by destroying the cell wall of microbes or interfering with their metabolism. It is also a form of decontamination, and can be defined as the process whereby physical or chemical methods are used to reduce the amount of pathogenic microorganisms on a surface.

The permissible exposure limit is a legal limit in the United States for exposure of an employee to a chemical substance or physical agent such as high level noise. Permissible exposure limits were established by the Occupational Safety and Health Administration (OSHA). Most of OSHA's PELs were issued shortly after adoption of the Occupational Safety and Health (OSH) Act in 1970.

The threshold limit value (TLV) is believed to be a level to which a worker can be exposed per shift in the worktime without adverse effects. Strictly speaking, TLV is a reserved term of the American Conference of Governmental Industrial Hygienists (ACGIH). TLVs issued by the ACGIH are the most widely accepted occupational exposure limits both in the United States and most other countries. However, it is sometimes loosely used to refer to other similar concepts used in occupational health and toxicology, such as acceptable daily intake (ADI) and tolerable daily intake (TDI). Concepts such as TLV, ADI, and TDI can be compared to the no-observed-adverse-effect level (NOAEL) in animal testing, but whereas a NOAEL can be established experimentally during a short period, TLV, ADI, and TDI apply to human beings over a lifetime and thus are harder to test empirically and are usually set at lower levels. TLVs, along with biological exposure indices (BEIs), are published annually by the ACGIH.

<span class="mw-page-title-main">Ethylbenzene</span> Hydrocarbon compound; precursor to styrene and polystyrene

Ethylbenzene is an organic compound with the formula C6H5CH2CH3. It is a highly flammable, colorless liquid with an odor similar to that of gasoline. This monocyclic aromatic hydrocarbon is important in the petrochemical industry as a reaction intermediate in the production of styrene, the precursor to polystyrene, a common plastic material. In 2012, more than 99% of ethylbenzene produced was consumed in the production of styrene.

<span class="mw-page-title-main">2-Butoxyethanol</span> Chemical compound

2-Butoxyethanol is an organic compound with the chemical formula BuOC2H4OH (Bu = CH3CH2CH2CH2). This colorless liquid has a sweet, ether-like odor, as it derives from the family of glycol ethers, and is a butyl ether of ethylene glycol. As a relatively nonvolatile, inexpensive solvent, it is used in many domestic and industrial products because of its properties as a surfactant. It is a known respiratory irritant and can be acutely toxic, but animal studies did not find it to be mutagenic, and no studies suggest it is a human carcinogen. A study of 13 classroom air contaminants conducted in Portugal reported a statistically significant association with increased rates of nasal obstruction and a positive association below the level of statistical significance with a higher risk of obese asthma and increased child BMI.

<span class="mw-page-title-main">Hydrogen selenide</span> Chemical compound

Hydrogen selenide is an inorganic compound with the formula H2Se. This hydrogen chalcogenide is the simplest and most commonly encountered hydride of selenium. H2Se is a colorless, flammable gas under standard conditions. It is the most toxic selenium compound with an exposure limit of 0.05 ppm over an 8-hour period. Even at extremely low concentrations, this compound has a very irritating smell resembling that of decayed horseradish or 'leaking gas', but smells of rotten eggs at higher concentrations.

2-Chloroethanol (also called ethylene chlorohydrin or glycol chlorohydrin) is an organic chemical compound with the chemical formula HOCH2CH2Cl and the simplest beta-halohydrin (chlorohydrin). This colorless liquid has a pleasant ether-like odor. It is miscible with water. The molecule is bifunctional, consisting of both an alkyl chloride and an alcohol functional group.

<span class="mw-page-title-main">Glycidol</span> Chemical compound

Glycidol is an organic compound that contains both epoxide and alcohol functional groups. Being bifunctional, it has a variety of industrial uses. The compound is a slightly viscous liquid that is slightly unstable and is not often encountered in pure form.

Selenium hexafluoride is the inorganic compound with the formula SeF6. It is a very toxic colourless gas described as having a "repulsive" odor. It is not widely encountered and has no commercial applications.

Vaporized hydrogen peroxide (trademarked VHP, also known as hydrogen peroxide vapor, HPV) is a vapor form of hydrogen peroxide (H2O2) with applications as a low-temperature antimicrobial vapor used to decontaminate enclosed and sealed areas such as laboratory workstations, isolation and pass-through rooms, and even aircraft interiors.

<span class="mw-page-title-main">Manure management</span> Agricultural practice

Manure management refers to capture, storage, treatment, and utilization of animal manures in an environmentally sustainable manner. It can be retained in various holding facilities. Animal manure can occur in a liquid, slurry, or solid form. It is utilized by distribution on fields in amounts that enrich soils without causing water pollution or unacceptably high levels of nutrient enrichment. Manure management is a component of nutrient management.

A short-term exposure limit (STEL) is the acceptable average exposure over a short period of time, usually 15 minutes as long as the time-weighted average is not exceeded.

Workplace exposure monitoring is the monitoring of substances in a workplace that are chemical or biological hazards. It is performed in the context of workplace exposure assessment and risk assessment. Exposure monitoring analyzes hazardous substances in the air or on surfaces of a workplace, and is complementary to biomonitoring, which instead analyzes toxicants or their effects within workers.

References

  1. 1 2 3 "The Myths of Sterilant Gas Safety Exposed". Infection Control Today. 16 April 2008.
  2. ↑ "Sterilant Gas Mixtures". SCI Analytical.
  3. ↑ "510(k) Summary - STERRAD 100NX Sterilizer" (PDF).
  4. ↑ "KO20875 TS03 125l Ozone Sterilizer" (PDF). Food and Drug Administration . Archived from the original (PDF) on 2006-10-05.
  5. 1 2 "Steri-Trac® Sterilant Gas Monitoring System" (PDF). ChemDAQ.
  6. ↑ "Index of Chemicals - NIOSH Publications and Products". CDC . 26 October 2017.
  7. ↑ "Ethylene Oxide". Medical Management Guidelines (MMGs). ATSDR. Archived from the original on May 28, 2010.
  8. ↑ "Manufacturer and User Facility Device Experience Database". FDA.
  9. ↑ P. Richard Warburton (July 2008). "The Essentials of Sterilant Gas Monitoring" (PDF). Managing Infection Control.
  10. ↑ 29 CFR 1910.1047
  11. ↑ 29 CFR 1910.1000, App. Z-1
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