Protective ratio

Ceramic Plates (Ceramic Bathroom Tiles) Gives excellent protection from small arms fire, but because the plate shatters upon bullet impact,the area 1s left unprotected from subsequent attack. Homemade ceramic armor is inexpensive, with a fairly good weight-to-protection ratio. The drawback is the need for immediate repair of the impacted area. This requires that the armor panels be accessible for rapid replacement of damaged units.An adequate supply of spares should be on hand. 

To date, the M291 SDK has not been used to decontaminate humans exposed to chemical agent. Extensive animal data suggest that the kit will provide significant protection to exposed soldiers. The resin itself was first tested for efficacy in rabbits with shaved backs that were exposed to soman, thickened soman, and VX. Two minutes after exposure, the animals were treated with the resin. The protective ratios were observed to be 2.0, 10.4, and 22.8, respectively (Joiner et al., 1988). 

Recent studies in the clipped haired guinea pig model using 1% soapy water and a 2 min decontamination delay demonstrated protective ratios for soman, cyclosarin, VX, and VR of 2.2, 6.0, 16, and 27, respectively (Braue, 2006 Hanssen et al., 2006). 

The therapeutic efficacy of oximes is usually focused on the evaluation of the protective ratio (PR), which is the ratio of the LD50 value of nerve agents for therapeutically protected animals to the LD50 value of nerve agents for unprotected animals. The authors usually publish data obtained from experiments where a combination of atropine and an oxime is used as an antidotal treatment because this possibility is much more relevant to anticipated military use than atropine or oxime alone. The results of published experiments are listed in Table 4(10, 32-47). 

NERVE AGENT Route of admin. OXIME Dose (umol/kq) Route of admin. Atropine dose Route of admin. Species Protective ratio Reference... 

In experimental studies, a delay of even 12 min in the administration of atropine and oxime reduced the protection ratio (LD50 with treatment/LDso without treatment) substantially, even in the case of nerve agents other than soman (Green el al., 1983 Table 2). While it is important that an oxime is administered as soon after soman exposure as possible, so that some reactivation of AChE occurs before all the enzyme becomes aged , early atropine and oxime administration is still clinically important in patients poisoned with other nerve agents, even though ageing occurs more slowly and reactivation occurs relatively rapidly. 

Table 2. Effect of delaying therapy (IV atropine, pralidoxime, diazepam) on protection ratios in guinea pigs given pyridostigmine 30 min before nerve agent (Green et al., 1983)...

Time of therapy Protection ratio (95% confidence limits) ... 

Protective ratio LD50 with treatment/LDso without treat-ment. 

Different doses of 2-PAM Cl were administered (with atropine) in several studies. In sarin-poisoned rabbits, the protective ratio (PR the ratio of the LD50 with treatment to the LD50 without treatment) increased from 25 to 90 when the intravenous dose of 2-PAM Cl increased from 5 mg/kg to 10 mg/kg144 the PR increased from 1.6 to 4.2 when the intramuscular dose of 2-PAM Cl increased from 30 mg/kg to 120 mg/kg in sarin-poisoned rats122 and the PR increased from 1.9 to 3.1 when the intramuscular dose of 2-PAM Cl increased from 11.2 mg/kg to 22.5... 

Group Mean LD50(pg/kg) [95% CL] Mean Protective Ratio [95% CL]... 

EFFECT OF THERAPY WITH AND WITHOUT PYRIDOSTIGMINE PRETREATMENT ON PROTECTIVE RATIOS IN ANIMALS EXPOSED TO NERVE AGENTS... 

Nerve Agent Animal Tested Protective Ratio ... 

A second area to vastly reduce exposure is the wearing of a full cover of clothes as described above. We did not measure the protection of clothes to any detailed extent, but we did find at least a 20 to 1 protection ratio under new but laundered jean material. With this ratio in mind and looking at the larger proportion of areas covered by just adding long sleeves to short ones, we calculated a reduction of at least 95Z from total body exposure by the wearing of clothing. 

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