Human Health and the Environment assignment 2.docx

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University of Toronto Scarborough
Environmental Science
Ingrid L.Stefanovic

Human Health and the Environment – Assignment #2 Name: Zakiyya Parekh Student Number: 998442546 Due Date: March 25, 2013 TA: Peter Quincy Ng 1 A.) i. EDI air = 1.50 g/kg*d ii. EDI skin = 3.7253 x 10ˆ-5 g/kg*d iii. The greatest exposure is through inhalation because the EDI for air is greater then the EDI for skin meaning there is a higher level of exposure to benzene through inhalation from the air then skin transfer. B.) i. RMOS = 4.352 ii. An RMOS value less than one is considered an acceptable risk to exposure and an RMOS value greater than one is considered an unacceptable risk of exposure. With this being said, the RMOS value calculated from our EDI total and RsD is about 4.35 which is far greater than one. Thus this level of exposure to benzene is not an acceptable risk and the chemical exposure poses a potential health risk. 2.a.) There a number of concerns when it comes to the potential human health risks of genetically modified crops. Firstly, there has been an issue with the tendencies of these crops to provoke allergic reactions. The transfer of genes from commonly allergenic foods is discouraged unless it can be demonstrated that the protein product of the transferred gene is not allergic (World Health Organization (WHO), 2013). Thus GM foods must be tested for allergenicity by the Food and Agricultural Organization of the United Nations and WHO prior to being put on the market (WHO, 2013). Next, gene transfer from GM foods to cells of the body or to bacteria in the gastrointestinal tract would cause concern if the transferred genetic material affects human health (WHO, 2013). For example, this would be relevant if antibiotic resistance genes were to be transferred. If genes coded for antibiotic resistance entered the food chain and were taken up by the human gut microflora, the effectiveness of antibiotics could be reduced and human infectious disease risk increased (WHO, 2013). Another concern has to do with outcrossing, the movement of genes from GM plants into conventional crops or related species in the wild which may have an indirect effect on food safety and food security (WHO, 2013). An example of this was when traces of maize type which was approved for feed use was also found in maize products for human consumption in the US (WHO, 2013). Also, concern has been expressed about the potential for pleiotropic and insertional mutagenic effects. Insertional effects are silencing of genes, changes in levels of expression or the turning on of existing genes that were not normally expressed due to a random insertion (Malarkey, 2003, p.220). Pleiotropic effects are unexpected new metabolic reactions arising from activity of the inserted gene on existing substrates or changes in flow rates through normal metabolic pathways (Malarkey, 2003, p.220). Lastly, there is a potential for intrinsic toxicity of transgene products. A protein has the potential to exert health effects if it is not digested or absorbed systematically (Malarkey, 2003, p.218). As a result, protein toxins are known to act on acute mechanisms at low doses (Malarkey, 2003, p.218). b.) Genetically modified crops have proven to
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