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Microsoft Word Toxicology and Exposure Guidelines doc
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| bet | 13/25 | | Sana | 13.02.2024 | | Hajmi | 281,22 Kb. | | #155571 |
Bog'liq tox exposure guidelines (1)
Kidneys. The kidney is susceptible to toxic agents for several reasons: (1) The kidneys constitute
1 percent of the body's weight, but receive 20-25 percent of the blood flow (during rest). Thus,
large amounts of circulating toxicants reach the kidneys quickly. (2) The kidneys have high
oxygen and nutrient requirements because of their workload. They filter one-third of the plasma
reaching them and reabsorb 98-99% of the salt and water. As they are reabsorbed, salt
concentrates in the kidneys. (3) Changes in kidney pH may increase passive diffusion and thus
cellular concentrations of toxicants. (4) Active secretion processes may concentrate toxicants. (5)
Biotransformation is high.
A number of materials are toxic to the kidneys:
• Heavy metals, may denature proteins as well as produce cell toxicity. Heavy metals
(including mercury, arsenic, gold, cadmium, lead, and silver) are readily concentrated in
the kidneys, making this organ particularly sensitive.
• Halogenated organic compounds, which contain chlorine, fluorine, bromine, or iodine.
Metabolism of these compounds, like that occurring in the liver, generates toxic
metabolites. Among compounds toxic to the kidneys are carbon tetrachloride,
chloroform, 2,4,5-T (a herbicide), and ethylene dibromide (a fumigant).
• Miscellaneous, including carbon disulfide (solvent for waxes and resins) and ethylene
glycol (automobile antifreeze).
Blood. The blood system can be damaged by agents that affect blood cell production (bone
marrow), the components of blood (platelets, red blood cells, and white blood cells), or the
oxygen-carrying capacity of red blood cells.
Bone Marrow. Bone marrow is the source of most components in blood. Agents that suppress
the function of bone marrow include:
• Arsenic, used in pesticides and paints.
• Bromine, used to manufacture gasoline antiknock compounds, ethylene dibromide, and
organic dyes.
• Methyl chloride, used as a solvent, refrigerant, and aerosol propellant.
• Ionizing radiation, produced by radioactive materials and x-rays is associated with
leukemia.
• Benzene, a chemical intermediate associated with leukemia.
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