Detection levels ethylene oxide

IV. Diagnosis is based on a history of exposure and typical upper-airway irritant effects. Detection of ethylene oxide odor indicates significant exposure. Industrial hygiene sampling is necessary to document air levels of exposure. 

Polymers. Studies to determine possible exposure of workers to residual epichl orohydrin and ethylene oxide monomers in the polymers have been done. Tests of warehouse air where Hydrin H and Hydrin C are stored showed epichl orohydrin levels below 0.5 ppm. Air samples taken above laboratory mixing equipment (Banbury mixer and 6" x 12" mill) when compounds of Hydrin H or C were mixed gave epichl orohydrin levels below detectable limits, and ethylene oxide levels less than 0.2 ppm, well below permissible exposure limits (46). A subacute vapor inhalation toxicity study in which animals were exposed to emission products from compounded Parel 58 suggests that no significant health effects would be expected in workers periodically exposed to these vapors (47). 

By using modem production methods it is possible to reduce the amounts of 1,4-dioxane to a level that is barely detectable with the best current analytical methods. Free ethylene oxide is now below detectable levels. Furthermore, volatile and nonvolatile nitrosamines ( NDELA ) both seem to be below detection limits of ppb in the alkanolamide-based sulfosuccinates. A good overview of modern analytical methods for the detection of 1,4-dioxane and ethylene oxide as well as nitrosamines and formaldehyde is given in Ref. 60. 

Absorbed ethylene oxide is rapidly distributed throughout the body. In mice exposed by inhalation to radiolabeled ethylene oxide, distribution was immediate, with the highest concentrations of ethylene oxide or its metabolites in the lungs, liver, and kidneys. After 4 h, levels in the liver and kidney had decreased and were comparable to those detected in the lungs, testes, spleen, and brain. 

Ethylene oxide does not penetrate some spices very well particularly when it is diluted in carbon dioxide so the effectiveness of the treatment is variable. Often a spice must be treated more than once to achieve the sterilization desired. After treatment, the spices should be allowed to outgas for a week (or until no residual ethylene oxide can be detected) to reduce the residual ethylene oxide levels. The process (less the out gassing time) takes generally 12-18 hours [10]. 

Ethylene oxide is a colorless gas under normal ambient conditions. It is odorless at low levels and cannot be detected by smell until the concentration is very high—above safe exposure levels. Above about 500 ppm, ethylene oxide has an etherlike odor. Selected physical characteristics of ethylene oxide are given in Table 3. 

A simple cyclic diester of carbonic acid is ethylene carbonate (7.96), a chemical with a toxicity profile resembling that of ethylene glycol (7.97). Metabolic studies have confirmed that ethylene carbonate is hydrolyzed very rapidly to ethylene glycol (whose oxidation is discussed in Chapt. 2 in [7]) and C02. Indeed, rats given an oral dose of ethylene carbonate did not excrete the unchanged xenobiotic in detectable amounts, and blood levels of the diester were ca. 100-fold smaller than those of ethylene glycol [178],... 

Prompted by a recent study which showed that EDB could be oxidized under anhydrous conditions to formaldehyde by the action of superoxide ion (29), we fortified water solutions with part-per-million concentrations of EDB, incubated them at elevated temperatures, analyzed them and found them to have low but consistent levels of formaldehyde, but only after all the EDB had been hydrolyzed. Studies conducted with natural and deionized water fortified to 10 ppm with ethylene glycol and incubated at 85°C showed that the amounts of formaldehyde detected varied from about 350 ppb to 2 ppm after 40 days of incubation. These findings... 

Miscellaneous Results. After the Vycor reactor was contacted with oxygen for several hours at 800°C, the activity of the reactor was Increased slightly. Both ethylene and propylene showed detectable reactions for almost 15 minutes at 500°C which Is 50°C lower than for the untreated reactor. Small amounts of carbon oxides were detected during this time Indicating that some oxygen had been adsorbed on the Inner Vycor wall. After all of the oxygen had desorbed, the activity of the reactor returned to a level similar to that In the untreated Vycor reactor. A steam treatment of the Vycor reactor at high temperatures did not, however, produce any noticeable Increase In the reactor activity. 

The experimental data on the transient separation of ethylene-ethane mixture represented in Fig. 7 demonstrate that permeability of ethylene reaches its steady-state level much faster than that of ethane. Of particular interest are the results at low time on stream values when the permeate consists of the essentially pure ethylene ethane in detectable concentrations appears in the permeate significantly later. These features give rise to the sharp increase in permselectivity at low times on stream where a values as high as 50-100 and more were registered. The initial gain in permselectivity is followed by the exponential decay in time. The relaxation time (i.e. time needed for the permeability to reach a steady-state value) is rather long - ca. 100 minutes for the 60 pm thick films of the polyphenylene oxides used in this study. 

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