Ocular exposure, reducing

Following dermal or ocular exposures to hydrazines, there are several methods by which absorption can be reduced. All contaminated clothing should be removed, and contacted skin should be washed immediately with soap and water (Bronstein and Currance 1988 Haddad and Winchester 1990 Sittig 1991 Stutz and Janusz 1988). Eyes that have come in contact with hydrazines should be flushed with copious amounts of water. Contact lenses should be removed prior to flushing with water. Proparacaine hydrochloride may be used to assist eye irrigation (Bronstein and Currance 1988). 

For accidental ocular exposure to ricin, extensive rinsing with 10% lactose solution may reduce toxicity if performed immediately after exposure (Strocchi et al., 2005). 

Despite the twentyfold to thirtyfold increase in the toxicity of lewisite compared to the mustards, the ocular injuries caused by vapor exposure to lewisite are predicted to be less significant than HD under field conditions (Gates et al., 1946). Ocular irritation is almost immediate even at low concentrations, such that exposed personnel would be alerted to the presence of an irritant and able to rapidly take protective action. Second, the rapid onset of blepharospasm, ocular pain, and edema at low concentrations causes the eyes to close involimtarily, reducing the total ocular exposure. 

Methods for Reducing Toxic Effects. The general recommendations for reducing the absorption of trichloroethylene following acute inhalation (HSDB 1994), oral (D Souza et al. 1985 Withey et al. 1983), dermal, or ocular (HSDB 1994) exposure are well established and have a proven efficacy. No additional investigations are considered necessary at this time. 

Marttila et al. (1995) also examined the relationship between daily exposure to malodorous sulfur compounds (measured as total reduced sulfur [TRS]) from pulp production and experience of symptoms in a small population living in the vicinity of a pulp mill. The major components of the malodorous sulfur compounds are hydrogen sulfide, methyl mercaptan, and methyl sulfides. This work was initiated due to the observation that an unusually high short-term exposure to malodorous sulfur compounds (maximum 4-hour concentrations of hydrogen sulfide at 135 g/m3 [96 ppb]) led to a considerable increase in the occurrence of ocular, respiratory, and neuropsychological symptoms (Haahtela et al. 

Dermal/Ocular Effects. Very few reports mention any effect of carbon tetrachloride inhalation on the skin. Inhalation exposure to carbon tetrachloride for several days in the workplace caused a blotchy, macular rash in one man (but not in six others) (McGuire 1932). Similarly, a hemorrhagic rash occurred in a woman exposed to carbon tetrachloride fumes for several days in the workplace (Gordon 1944), and black and blue marks were seen in a patient exposed intermittently to carbon tetrachloride vapors for several years (Straus 1954). Because observations of dermal effects are so sporadic, it is difficult to judge whether these effects are related to carbon tetrachloride exposure, or are incidental. Conceivably, they may have been secondary to reduced synthesis of blood coagulation factors resulting from carbon tetrachloride-induced hepatotoxicity. No studies were located regarding ocular effects in humans or animals after inhalation exposure to carbon tetrachloride. 

Comeal organ culture combined with objectively quantifiable assays for comeal epithelial barrier disruption reduces the high variability associated to the subjectively scored Draize Test. The FITC-Dextran retention has been studied as a quantitative evaluation of the comeal epithelial barrier (Lopez et al. 1991) following chemical exposure of bcnzal konium chloride (BAC), Polyquad, and Thimerosal. Sodium dodecyl sulfate (SDS) has also been tested for disruption of the tight junctions via FITC-Dextran retention assay. However, as an objective outcome measure for ocular toxicity, the scoring system is not yet quantitatively comparable for assessment of ocular irritancy to multiple test products. This limitation is similar to surface biotinylation assays. As fluorometry is utilized more extensively in varied laboratories with numerous test chemicals a standardized scoring system can be elicited similar to the familiar Draize Test. 

Methods for Reducing Toxic Effects. Limited information is available on treatments to alleviate the symptoms of tetryl exposure. These include treatment of the dermatitis with calamine lotion and/or zinc oxide preparations, treatment of dermatitis and ocular irritation with aluminum acetate or boric acid compresses, and treatment of hypersensitivity-like symptoms (including severe dermatitis and asthma-like symptoms) with epinephrine or antihistamines (Bain and Thomson I 954 Bergman 1952 Cripps 1917 Eddy 1943 Ruxton 1917 Smith 1916 Troup 1946 Witkowski et al. 1942). The data on the pharmacokinetics of tetryl are also limited (Zambrano and Mandovano 1956). In order to develop mitigating agents, further studies are needed on its kinetics and mechanisms of action. 

The basic ocular irritation test in the rabbit will be described in detail in another section, but it is important to point out that the number of test animals can be reduced from the usual six at each exposure level to two or, at most, three animals per dose without sacrificing much accuracy. Many test series have shown 88-91% accuracy with two animals per treatment group. The agent, instilled in the pouch formed by the lower eyelid, is held in place for 1 s and then released. The treated eye is not washed, allowing the animal s own tear secretions to flush out the material. The untreated eye serves as a control. Both eyes are examined at 1, 24, 48, and 72 h after treatment, the irritation (or damage) to the cornea, the conjunctiva, and the iris being scored numerically in a subjective manner. The test is open in that the experiment can be terminated at 72 h if there is no evidence of irritation, but observed effects can be assessed for a longer time period. 

Overcoming the stress produced in a chemically threatening environment requires information on the nature of the threat and confidence that every possible step has been taken to eliminate or minimize the threat. Correct use of a gas mask can eliminate a great portion of the mustard gas injury by eradicating ocular and respiratory injuries. Proper use of sensors and military intelligence will reduce the risk of exposure and, therefore, of stress. 

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