Essay On Arsenic Methylation

and MMA(III). According to some reports the vitamin B12 can be a cofactor in the methylation process of arsenic and assists in transforming MMA to DMA, but this has been disproven by some reasearchers.

There are two different mechanisms for arsenic methylation: Classical pathway (oxidative methylation) and Glutathione conjugation pathway (reductive methylation). In oxidative methylation, proposed by Challenger, arsenic comes together with a methyl group to create neutral methylated arsenicals like (MMAV) and (DMAV). The arsenic-sulfur compounds are replaced with unconjugated trivalent arsenicals, which is very similar to glutathione conjugation. Hayakawa was the first to bring forth a study on Glutathione conjugation. In this conjugation, trivalent arsenic conjugates with GSH first and arsenic glutathione conjugates serve as substrates. Reductive methylation is believed to proceed as arsenic-glutathione conjugates.

The toxicity of arsenicals can be attributed to the production of oxidative stress and reactive oxygen species (ROS). Different forms of arsenic can cause more or less oxidative stress to different cells depending on their concentrations. The toxicity also depends on the cellular uptake rates for different forms of arsenic. For different forms the uptake orders are as follows: for iAsIII it’s (DMAIII) > (MMAIII) > (iAsIII), and for iAsV it’s (iAsV) > (MMAV) > (DMAV) > trimethylarsine oxide (TMAOV). When studying arsenic toxicology it has been observed that GSH boosts DMAV toxicity but decreases MMAV, iAsIII, and iAsV toxicity. The LD50 for humans is said to be around 1-2 mg/kg. There are many different forms of arsenic that exist in different places. In anaerobic conditions, arsenic can be found as arsenate (iAsV) o...

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... required the FDA to set standards for the amount of arsenic allowed in fruit juices. Rep. Frank Pallone, D-N.J., and Rep. Rosa DeLauro, D-Conn. were the two representatives that pushed this bill forward after reading about the arsenic levels determined by Reports. This juice was mostly for children, and as a result many parents became very concerned.

The controversy of arsenic in fruit juice became a big topic of discussion after Mehmet Oz, M.D., who is the host of “The Dr. Oz Show,” said that he authorized tests that proved there were arsenic levels in fruit juice that exceeded the 10 ppb limit set on bottled water. In 2012 Consumer Reports found traces of arsenic and lead in fruit juices, which lead the FDA to step in and set new standards. At that time, there were standards for arsenic levels in water but not in fruit juice. The Environmental Protection Agency