ACCIDENTAL DECONTAMINATION

In a brief review of chemical accidents caused by accidental contamination of process materials, attention is drawn to the much less frequent opposite effect of accidental decontamination (or purification) as a cause of accidents. Some examples of the effects arising from accidental loss or inactivation of stabilisers or antioxidants from reactive materials are given. 

Accidental pollution incidents arise from spillages, gas emissions, and liquid discharges sometimes in transportation. The main considerations are prevention, containment, and effective mitigatory and emergency action according to the principles outlined in earlier chapters. Effective clean-up and decontamination are then needed. 

Decontaminants. Area decontamination is not required as CS has a short duration, of effectiveness. Personnel exposed to CS may shower as necessary however, when CS dust or particles are on the skin, showering should be delayed for 6 hours to prevent stinging and reddening of the skin. Individuals affected by CS should move to fresh air, face the wind, and remain well spaced and should not rub their eyes. To remove accidental gross contamination, personnel should remove clothing and immediately flush body with copious amts of water to remove most of the agent apply 5% Na bisulfite soln to remove remainder (except in or around eyes) and then rinse body... 

When you are dealing with sites where agents have been applied, personnel safety and your is your highest priority. Special clothing, respiratory protection, sample collection and analyses procedures and decontamination procedures are all required before one begins characterization and any site work. The possibility of accidental exposure and accident prevention has to be continually considered. 

While the literature indicates that the half life of various degradation products of VX have a soil half life of greater than 100 days, except MPA, the relative toxicity of the compounds suggests that the contact of persoimel and contaminated materials should be prevented, and the disposition of the site must be final and address surfaces which are difficult to decontaminate because of size or porosity or both. The material is too dangerous to permit any chance of an accidental release from a partially decontaminated site. 

A lthough the levels of plutonium in environmental waters are generally - low, there is the possibility of plutonium contamination from weapons testing, nuclear reactor operations, laundry and decontamination wastes, fuel reprocessing, and accidental release during transportation. It has been estimated that by 1980 the United States will be producing 15,000-20,000 kg. of plutonium per year (12). Its growing use will increase the probability of environmental contamination. 

A particular aspect of water treatment is the rehabilitation of accidentally contaminated soils by radionuclides. This is well illustrated by the works carried out after the Cernobyl catastrophe. The incorporation of clinoptilolite into contaminated soils reduced the transport of heavy metals and radionuclides from soils into ground water and biomass (7). Union Carbide s IONSIV EE-95 (CHA) and A-51 zeolites (LTA) with excellent Cs+/Na+ and Sr2+/Na+ selectivities, respectively, have also been employed for decontamination of high activity level water in the reactor containment building from Cs+ and Sr2+ after the accident at Three Miles Island (5). The radioisotope loaded zeolites were then transformed into glasses for ultimate disposal. 

Accidental ingestion of a small piece or less than a few pellets can be adequately managed at home by Poison Control Centers, or by a healthcare professional with home observation and parent education. Usually, these types of exposures do not require any medical intervention or routine follow-up laboratory studies. Gastric decontamination has no effect on the clinical outcome after taste amounts are ingested by children (Kanabar and Volans, 2002 Mullins et al, 2000 Shepherd et al, 2002). 

In 1998, a source was accidentally melted in a stainless steel production factory in Spain. As a consequence of this accident, the cooling system of one of the ovens became radioactively contaminated. The decontamination process produced 40 m of Cs contaminated water, with an average activity above 300 kBq/L. 

A new process foi the decontamination of bottom tank petroleum sludges was submitted to a laboratory feasibility study. This process mainly consists a water-yapor extraction (digestion), extruding the oil particles from their support of sand or day. It can efficiently be utilized to clean the sand of a beach contaminated by an accidental heavy oil spill. 

A patient with congestive heart failure has accidentally taken an overdose of digoxin. The blood concentration of the drug is eight times the threshold for toxicity. Pharmacokinetic parameters for digoxin include a clearance of 7 L/h and an elimination half-Ufe of 56 hours. If no procedures are instituted to decontaminate this patient, the time taken to reach a safe level of digoxin will be approximately (A) 3.5 days 7 days 14 days 28 days 56 days... 

To minimize the possibility of ingestion as well as the chances of ruining experiments through accidental contamination, limiting the radioactive work to a minimum area is essential. There should be no radioactivity exc t in the immediate working area, and upon conq>letion of the particular experimrait, all activity should be removed and the area cleaned decontaminated) if necessary. For low levels, this means working in a good hood with easily cleaned nonporous surfaces. 

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