Abstract
Maize seedlings of the genotype C I Sh Wx were fumigated with hydrogen fluoride gas (HF) continuously for 4, 6, 8 and 10 days. Miscrospore mitosis of the treated plants indicated the presence of fragments and bridges suggesting the occurrence of the phenomenon of breakage-fusion-bridge cycle of McClintock. This phenomenon was later confirmed by the production of endosperm mosaicisms. The period of fumigation was clearly related to the extent of the area resulting from the B-F-B cycle. Recombination values were estimated from F2 data for the regions C-sh and sh-wx. There was a significant increase in the frequency of crossing over for region I with maximum increase being for the 4 days duration. The recombination value for region II showed no significant deviation from the control. These findings indicate that HF in addition to being a mutagenic agent is also able to reduce crossing over in certain chromosome segments.
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Cytotoxic and phytotoxic effects of the main chemical components of spent pot-liner: A comparative approach
Spent pot-liner (SPL) is a hazardous solid waste produced by the aluminum industry. Although its composition may vary, fluoride and cyanide salts as well as aluminum are predominant components. A seed-germination and root-elongation test was performed with Lactuca sativa seeds as a test system. SPL induced decrease of seed germination
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Sister chromatid exchanges: a study in fluorotic individuals of North Gujurat
The purpose of this preliminary investigation was to compare the genotoxic effect of fluoride in human individuals directly exposed to high concentrations of drinking water fluoride (1.95 to 2.2 ppm) with those in individuals exposed to concentrations (0.6 to 1.0 ppm) within the WHO permissible limit. Sister chromatid exchanges (SCE)
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No relationship between subchronic fluoride intake and DNA damage in Wistar rats.
Fluoride has been widely used in dentistry because it is an effective caries prophylactic agent. However, excess fluoride may represent a hazard to human health, especially by causing injury on the genetic apparatus. Genotoxicity tests form an important part of cancer research and risk assessment of potential carcinogens. In the
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Clastogenic activity of sodium fluoride in great ape cells
Conflicting evidence has been reported concerning the mutagenicity of sodium fluoride (NaF), especially clastogenicity at concentrations of more than 1 mM. NaF is known to induce chromosome aberrations at these concentrations in human cells, but not in most rodent cells. We considered that such species-specific difference in chromosomal sensitivity would
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Clastogenic activity of sodium fluoride to rat vertebral body-derived cells in culture
The US National Toxicology Program has shown equivocal evidence of carcinogenic activity of sodium fluoride (NaF) in male F344/N rats based on the occurrence of five osteosarcomas in treated animals. In the study the osteosarcomas developed mainly in the rat vertebrae. To provide a possible mechanistic basis for the observed
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Fluoride & Osteosarcoma: A Timeline
Several human epidemiological studies have found an association between fluoride in drinking water and the occurrence of osteosarcoma (bone cancer) in young males. These studies are consistent with the National Toxicology Program's (NTP) cancer bioassay which found that fluoride-treated male rats had an dose-dependent increase in osteosarcoma. Although a number of studies have failed to detect an association between fluoride and osteosarcoma, none of these studies have measured the risk of fluoride at specific windows in time, which based on recent results, is the critical question with respect to fluoride and osteosarcoma.
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NTP Bioassay on Fluoride/Cancer (1990)
In 1977, the U.S. Congress requested that animal studies be conducted to determine if fluoride can cause cancer. The result of the Congressional request was an extensive animal study conducted in the 1980s by the National Toxicology Program (NTP) and published in 1990. The main finding of NTP's study was a dose-dependent increase in osteosarcoma (bone cancer) among the fluoride-treated male rats.
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A Critique of Gelberg's Study on Fluoride/Osteosarcoma in New York
The case-control study by Gelberg, published first as a PhD dissertation and then later in two peer-reviewed journals, may represent the most substantive study on fluoride/osteosarcoma previous to Bassin’s 2001 analysis. In assessing Gelberg’s data, we were at first struck by the existence of several notable errors in both the thesis and papers. While these errors do raise questions about the study, our primary concern with Gelberg’s work relates to the methods she used to analyze her data.
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Fluoride & Liver Cancers in NTP Bioassay
On October 28, 1988, Battelle Columbus Laboratories submitted its Final Report to the NTP concerning the results of the Mouse study. The principal finding of Battelle's report was that a dose-dependent increase of a rare liver cancer (hepatocholangiocarcinoma) had occurred in the fluoride-treated male and female mice.
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Fluoride's Mutagenicity: In vivo Studies
Consistent with dozens of in vitro studies, a number of in vivo studies, in both humans and animals, have found evidence of fluoride-induced genetic damage. In particular, research on humans exposed to high levels of fluoride have found increased levels of "sister chromatid exchange" (SCE). As noted in one study: "In
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