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GXFOXNGT PIP-MGTI IYL BROMIDE http://acc.orst.cdu/cgi-bin/mis/01/pips/methylbr.htm
<br /> • Acute toxicity: Since bromomethane is a gas at ambient temperatures, the most significant route of
<br /> exposure is inhalation [188]. The reported 1-hour inhalation LC50 in rats is 4.5 mg/L, and the
<br /> 11-hour LC50 in rabbits is 8 mg/L [8]. Inhalation of 6 mg/L for 10 to 20 hours, or 30 mg/L for 1.5
<br /> hours is lethal to humans [8]. The compound is readily absorbed through the lung alveoli (gas
<br /> exchange regions). Methyl bromide can be highly irritating to the mucous membranes of the eyes,
<br /> airways, and skin with contact [17]. About 1000 human poisoning incidents caused by methyl
<br /> bromide exposure have been documented, with effects ranging from skin and eye irritation to death
<br /> [17]. Most fatalities and injuries occurred when methyl bromide was used as a fumigant. The lowest
<br /> inhalation level found to cause toxicity in humans is 0.14 mg/L in air [17]. A typical delay in onset
<br /> of symptoms following exposure combined with an odor threshold (level at which most people can
<br /> smell it) well-above the level at which toxic effects occur, means that the victim may not realize a
<br /> harmful exposure is occurring until it is too late [17]. Initial acute effects may include headache,
<br /> dizziness, nausea or vomiting, chest and abdominal pain, and irritated eyes, nose, and throat [1881.
<br /> With sufficient exposure, symptoms of slurred speech, blurred vision, temporary blindness, mental
<br /> confusion, and sweating may occur [188]. More severe symptoms at even higher doses may include
<br /> lung swelling; congestion; hemorrhaging of the brain, heart, and spleen; severe kidney damage; and
<br /> numbness, tremors, and convulsions [188]. The nervous effects observed in lab animals included
<br /> degeneration of key nerve cells in various portions of the brain and peripheral nervous system
<br /> [188]. Death may occur from respiratory failure [188]. The rat oral LD50 (bromomethane
<br /> administered as a liquid, or in solution) is 214 mg/kg [1], also indicating moderate to high toxicity.
<br /> • Chronic toxicity: Chronic exposure to methyl bromide can cause extensive damage to neurons
<br /> (nerve cells) involved in cognitive processes and physical coordination or muscular control [188].
<br /> These effects were seen in rats exposed to 0.51 to 1.3 mg/L 6 hours per day for 5 days [188]. Rats
<br /> exposed to 65 ppm over 4 weeks for an average of 7 hours per day for 4 to 5 days did not show
<br /> neurological effects, but this level of exposure did result in severe, in some cases irreversible,
<br /> neurological effects in rabbits over a similar time period [188]. Exposure levels of 0.1 mg/L over 8
<br /> months (7.5 hours per day, 4 days/week) did not produce observable neurotoxicity [188]. The
<br /> symptoms of chronic exposure may include dizziness,vision and hearing disturbances, depression,
<br /> confusion, hallucinations, euphoria, personality changes, and irritability [8]. A chronic
<br /> pneumonia-like syndrome may become apparent after repeated exposure to sufficient levels [8].
<br /> Other targets of the fumigant identified through long-term animal studies are the heart, adrenal
<br /> gland, and the testis [189].
<br /> • Reproductive effects: No reproductive efffects were seen in rats exposed to up to 0.3 mg/L for 7
<br /> hours/day, 5 days a week, for 3 weeks prior to mating and during gestation [188]. This suggests that
<br /> methyl bromide does not cause reproductive effects.
<br /> • Teratogenic effects: No teratogenic efffects were seen in rats exposed to up to 0.3 mg/L for 7
<br /> hours/day, 5 days a week, for 3 weeks prior to mating and during gestation [188]. This evidence
<br /> indicates that bromomethane is unlikely to cause teratogenic effects.
<br /> • Mutagenic effects: Mutagenic effects were seen in mouse cell cultures, mutagenicity assays with
<br /> bacteria, and in in human white blood cells [190]. Rat liver cells did not display increased rates of
<br /> mutation after exposure to methyl bromide [190]. Methyl bromide is considered to be weakly
<br /> mutagenic [188].
<br /> • Carcinogenic effects: In one study of industrial workers exposed to various brominated
<br /> compounds, exposure to methyl bromide was suggested as the possible common factor in two fatal
<br /> cases of testicular cancer, but other exposures could not be ruled out [189]. In a rat study, methyl
<br /> bromide given at 50 mg/kg/day by stomach tube for 90 days (gavage) induced stomach tumor
<br /> increases [188,190]. It appeared that the cancerous growth was due to severe localized cellular
<br /> injury, with subsequent increased cell reproduction to repair tissue damage amplifying the natural
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