Flammable Cabinets for Ethylene Oxide Must be Vented.

Many hospitals use ethylene oxide (EtO) for low temperature sterilization despite the faster cycle times of competing technologies using hydrogen peroxide or ozone because of its great efficacy, broad application (lumens, cellulose products can all be sterilized) and much less damage to certain medical devices than the oxidative sterilants. EtO sterilization used to be supplied in tanks, blended with non-flammable balance gases, but the modern trend is to use single use cartridges with about 100 to 170 g of 100% EtO in them. These single use cartridges greatly improve safety compared to the older tanks because if there is a leak the amount of EtO involved is much smaller and cylinders no longer have to be changed. As with all the sterilant gases, EtO poses health risks for anyone exposed to it. It has the same OSHA permissible exposure limit (PEL) and hydrogen peroxide, (1 ppm calculated as an 8 hr time weighted average (EtO 29 CFR 1910.1047, H2O2 29 CFR 1910.1000 Tbl Z-1 because of EtO’s toxicity and carcinogenicity. In addition, EtO is a flammable low boiling point liquid (BP = 12 oC) and so should be stored in an NFPA approved flammable cabinet (NFPA 30). Most hospitals that we visit do store their single use cartridges in flammable cabinets, but a surprising number do not vent the cabinets. These single use cartridges often seep small amounts of EtO. If the cartridges were in the open, the EtO seepage though not good would be dispersed into the air and with the high air turn over in most sterile processing departments, not pose a great threat. However, if the cartridges are in an unvented flammable cabinet, the EtO that seeps from the cartridges can accumulate within the cabinet to be released only when the door is opened. We have seen a surprisingly large number of unvented flammable cabinets being used to store EtO single use cartridges. Facilities are using flammable cabinets because of the flammability of EtO, but are ignoring the toxicity of EtO. Hospitals that use EtO are required to have a dedicated exhaust and so in most cases the cost of connecting the EtO flammable cabinet to the exhaust is minimal. If the EtO flammable cabinet in not vented then the cost in terms of employees health in the long term may be much larger. It is not just ChemDAQ that is raising this concern, 3M, one of the major suppliers of these single use cartridges also recommends the use of vented flammable cabinets. Most flammable cabinets have vents built into the side of them by the manufacturer, and so exhaust ducts can easily be connected to the flammable cabinets using standard plumbing fixtures. It is important that the cabinets be actively vented, i.e. the gas inside the cabinet is sucked out. Simply opening the vents on the side of the cabinet and relying on air diffusion does not suffice since air diffusion is relatively slow especially if there are flame arrestor grids in the vent holes. In summary, EtO cartridges should be stored in a flammable cabinet, but since EtO has such a low PEL, the cabinet should be actively vented to prevent exposure of workers using the EtO cartridges to EtO.

Workers Memorial Day

Tomorrow, April 28th is Workers Memorial Day, a day when we remember those people who died from injuries in the workplace. Secretary of Labor Hilda L. Solis issued a statement saying "Tomorrow, April 28, is Workers' Memorial Day, an occasion for reflection and remembrance of the thousands of workers who needlessly have suffered fatal injuries on the job every year. We also think of those workers who have been seriously injured or sickened as a result of preventable workplace hazards. "We are never prepared to say goodbye to the people we love, but we are even less so when we send our loved ones off for a day's work. It is our duty to ensure that all workers come home safely at the end of each workday, and we stand behind our firm conviction that workplace injuries and fatalities are entirely preventable. "On this day, I urge all Americans to raise their voices in support of workers' right to a safe and healthful workplace. In the 41 years since the Occupational Safety and Health Act was enacted, we have made tremendous progress, but our steadfast mission to make every job in America a safe job must continue. One workplace death is too many. Making a living shouldn't include dying.". And as the Secretary has said previously "With every one of these fatalities, the lives of a worker's family members were shattered and forever changed. We can't forget that fact." These statistics report tragic accidents that occur suddenly and with immediate impact, however many workplace injuries, such as those that result from chemical exposure may not produce symptoms for many years and so are not counted in the work place safety statistics. We know that many chemicals used in the workplace are carcinogenic and for a select few, OSHA has promulgated 27 legally binding standards covering nearly 40 carcinogens. However, there are hundreds of known human carcinogens according to International Agency for Research on Cancer and the National Toxicology Program. These organizations also name a much larger number of compounds that are suspected carcinogens. The American Cancer Society has them in a convenient list. This list is conservative and only includes those compounds shown to cause cancer or with incriminating evidence against them. The actual number of cancer causing compounds is certainly much higher. Cancer is one of the major causes of death in the US. In 2010, according to the CDC it was the second leading cause of death behind heart disease with 567,628 out of 2,437,163 deaths. and in 2012 the American Cancer Society estimates there will be 1,638,910 new cases of cancer. In pre-industrial cultures, while cancers did occasionally occur, they were very rare, indicating that cancers are largely caused by environmental factors; see for example Cancer As an Environmental Disease, By P. Nicolopoulou-Stamati, 2004 There are many different types of cancer and for those interested, the probability of a man or woman dying from a particular type of cancer has been tabulated. While exposure to cancer causing agents occurs in many aspects of life from smoking to exposure to benzene in gasoline, workplace exposures are considered to be at higher levels than for public exposures. We know that we are all exposed to many cancer causing agents, especially in the workplace, that many people will develop cancer from reasons unknown and that a large proportion of them will die of it. However, it is very rare that somebody with a cancer diagnose can be associated with exposure to a particular chemical. We don’t know what proportion of the over half million people who will die from cancer this year will do so because of workplace exposure, but it is likely that this number of hidden workplace fatalities far exceeds the 4,690 fatal workplace accidents (2010) that we are remembering tomorrow.

Global harmonization Standards and the EPA

Recently OSHA provided a final rule for how it was going to change its hazard Communication standard 29 CFR 1910.1200 to reflect the global harmonization on chemical hazards (see earlier discussions of this topic in this blog).

The EPA operates under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and has its own regulations for describing chemical hazards on a safety data sheet. As a first step towards harmonization, on April 20th the EPA will publish a notice of the differences between its requirements for safety data sheets and OSHA's in the Federal Register.

We all know that regulations change at a glacial pace, and while this notice is not actually harmonization, hopefully this is the first small step in the right direction.

The ChemDAQ blog will continue to follow this story.