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XTOXNET PIP - PARATHION Page 3 of 5
<br /> LC50 in trout is 1.6 mg/1, 1.8 mg/1 in goldfish, 2.7 mg/l in catfish, 0.3 mg/l in mo squito fish, and 0.02 mg/I in
<br /> bluegill (Hdbk Acute Tax. Chem. Fish& Aquatic Inverts. 1980). (NIOSH RTEC S Online File # 84/8406).
<br /> . Effects on Other Animals (Non-target species): The 24-hour LD50 for parathion in honeybees is 0.07 to
<br /> 0.10 ug/bee when applied topically (3). The LD50 for parathion in mule deer is 22-44 mg/kg (Hdbk Acute
<br /> Tox. Chem. Fish & Aquatic Inverts. 1980). (NIOSH RTECS Online File# 84/8406). Some fat storage of
<br /> parathion does occur. However,upon release from fat storage, parathion is rapidly broken down and
<br /> eliminated. Bioconcentration of parathion is low to moderate. There is no evidence of bioaccumulation of
<br /> parathion in cattle, sheep or rabbits (10).
<br /> ENVIRONMENTAL FATE
<br /> . Breakdown of Chemical in Soil and Groundwater: Parathion has little or no potential for groundwater
<br /> contamination (3). It binds tightly to soil particles and is degraded by biological and chemical processes
<br /> within several weeks. Degradation is faster in flooded soil. Residues of parathion can persist for many years,
<br /> but usually remain in the upper 6 inches of soil. Photodegradation may occur on soil surfaces (10). Sunlight
<br /> can convert parathion into the active metabolite paraoxon, which is more toxic than parathion. The breakdown
<br /> of parathion in soil or water increases with increasing (more alkaline)pH. Soil microorganisms, sunlight,
<br /> plants and water all break parathion down.
<br /> . Breakdown of Chemical in Water: In open water, parathion will usually disappear within a week, mainly by
<br /> adsorption to suspended particles and bottom sediments. Adsorbed parathion is subject to degradation by
<br /> microorganisms and chemical hydrolysis. The half-life for photo-degradation of parathion in water is 1 to 10
<br /> days. Increasing the pH (alkalinity), increases the rate of breakdown(10).
<br /> w Breakdown of Chemical in Vegetation: Following spray applications, parathion residues on foliage will
<br /> decay with a half-life of I day, reaching low levels in a week or two (10). In orange groves, the half-life of
<br /> parathion is as long as one month. Usually, it is closer to one-two-weeks. Most crops tolerate parathion very
<br /> well. Only at high application rates do apples, cucumbers, and tomatoes suffer from parathion usage (8).
<br /> PHYSICAL PROPERTIES AND GUIDELINES
<br /> Parathion hydrolyzes slowly at pH 7 or below, but is otherwise stable at normal temperatures (3). At temperatures
<br /> N above 120 degrees C, parathion decomposes and may develop enough pressure to cause containers to explode.
<br /> Thermal decomposition may release toxic gases such as diethylsulfide, sulfur dioxide, carbon monoxide, carbon
<br /> dioxide, phosphorus pentoxide, and nitrogen oxides (3). Parathion poses a fire and explosion hazard in the presence
<br /> of strong oxidizers. It may attack plastics, rubber and coatings (11). Persons who work with organophosphate
<br /> materials for long periods of time should have frequent blood tests of their cholinesterase levels. If the
<br /> cholinesterase level falls below a critical point, no further exposure should be allowed until it returns to normal (15).
<br /> Protective clothing must be worn when handling fenthion. Before removing gloves, wash them with soap and water.
<br /> Always wash hands, face and arms with soap and water before smoking, eating or drinking. After work, remove all
<br /> work clothes and shoes. Shower with soap and water. Wear only clean clothes when leaving the job. Wash
<br /> contaminated clothing and equipment with soap and water after each use. Keep contaminated work clothes separate
<br /> from regular laundry.
<br /> rThe National Fire Protection Agency ratings for parathion include: A. health: 4 = a few whiffs of the fumes could
<br /> prove fatal; normal fire fighting gear is inadequate to protect against any exposure to the skin. B. flammability: 1 =
<br /> solids which must be preheated to burn, but which are combustible. It may be dangerous to use water to extinguish
<br /> burning parathion. C. reactivity: 2 = normally unstable materials which will react violently (with water). Also, it is
<br /> } potentially explosive when mixed with water (18).
<br /> l
<br /> Physical Properties:
<br /> . Appearance: Pure parathion is a pale yellow liquid with a faint odor of garlic at temperatures above 6 degrees
<br /> C. Technical parathion is a deep brown to yellow liquid (2, 11).
<br /> r . Chemical Name: 0,0-diethyl 0-4-nitrophenyl phosphorothioate
<br /> . CAS Number: 56-38-2
<br /> . Molecular Weight: 291.3
<br /> . Water Solubility: 12.4 mg/l at 25 degrees C (3); 24 ppm (11)
<br /> . Solubility in Other Solvents: Soluble in alcohols, animal & vegetable oils, aromatic hydrocarbons, esters,
<br /> ethers, n-hexane, dichloromethane, 2-propanol, toluene and ketones. Insoluble in kerosene, petroleum ether, or
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