Radiation toxicity, animals

Models of radiation damage have been explored and are well developed. For many years, accidental releases of ionizing radiation have been universally feared. Alternatively, radiation has been used in controlled, defined amoimts as a therapy for certain tumors in both companion animals and humans. Taken together, all studies provide a cohesive and comprehensive picture of radiation toxicity. There are sufficient details of radiation effects to make credible estimates of risk resulting from radiation exposure (Harley 2001, 2008). 

Animals receiving fractionated external radiation therapy for mammary tumors may develop chronic pulmonary degenerative disease because the thorax is irradiated. To achieve the desired therapeutic effect, the dose may be too high to heal by primary intent thus, they will heal by secondary intent - frbrosis. Type II cell proliferation is a common early event in radiation toxicity to the limgs. 

The supposition that ozone is mutagenic or carcinogenic in man is based primarily on information on the biochemical mechanism of ozone toxicity and to a lesser extent on in vitro and animal studies. The biochemical evidence is for the most part indirect and depends on an analogy between the free-radical nature of ozone toxicity and of radiation and other carcinogenic agents. 

Some compounds, such as strontium chromate and strontium fluoride, are carcinogens and toxic if ingested. Strontium-90 is particularly dangerous because it is a radioactive bone-seeker that replaces the calcium in bone tissue. Radiation poisoning and death may occur in people exposed to excessive doses of Sr-90. Strontium-90, as well as some other radioisotopes that are produced by explosions of nuclear weapons and then transported atmospherically, may be inhaled by plants and animals many miles from the source of the detonation. This and other factors led to the ban on atmospheric testing of nuclear and thermonuclear weapons. 

Heat Transfer The movement and dispersion of heat by conduction, convection, or radiation. Heavy Metals High-density metallic elements generally toxic to plant and animal life in low concentrations (e.g. mercury, chromium, cadmium, arsenic, and lead). 

Preconceptual and transplacental carcinogenesis are special types of developmental toxicity and can result when either parent is exposed prior to mating. Both male-mediated and female-mediated effects have been demonstrated in experimental animals for a variety of chemicals and several types of radiation (Anderson, 2000). Transplacental carcinogenesis is recognized in the female, but carcinogenesis mediated through the male germ cells is not as well appreciated or understood. 

Although this has been shown to occur in experimental animals after exposure of males to foreign compounds such as cyclophosphamide, there is only inconclusive evidence that this occurs in humans. Thus, studies of exposure of human males to vinyl chloride, dibromo-chloropropane, and anesthetic gases, for example, have revealed only equivocal evidence of developmental toxicity in the offspring. There now seems to be some evidence that the leukemia occurring in children, which appears to be clustered around nuclear fuel-reprocessing plants such as Sellafield in the United Kingdom, may be due to paternal exposure to radiation. 

The list of potentially hazardous materials includes drugs, food additives, preservatives, ores, pesticides, dyes, detergents, lubricants, soaps, plastics, extracts from plant and animal sources, plants and animals that are toxic by contact or consumption, and industrial intermediates and waste products from production processes. Some of the information refers to materials of undefined composition. The chemicals included are assumed to exhibit the reported toxic effect in their pure state unless otherwise noted. However, even in the case of a supposedly pure chemical, there is usually some degree of uncertainty as to its exact composition and the impurities that may be present. This possibility must be considered in attempting to interpret the data presented because the toxic effects observed could in some cases be caused by a contaminant. Some radioactive materials are included but the effect reported is the chemically produced effect rather than the radiation effect. 

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