| Student: Wang SinglingMentor: Gao Xing professor/researcher1. Research Background and Aims2-ethoxyethanol (EE) was widely used in weave, plastic, coating, varnish, adhesive, anti-icing additive, printing and wood manufacture et al because of its good characteristics of both being miscible with water and organic solvents. In our country, it was in the middle of 70s that the production and techniques of EE were introduced. Now it was used mainly in printing as the main component to producing printing photo sensitization (PS) plates liquid for laser photo typesetting, coating, paint and lacquer for the furniture and other solution to membrane substances.In the working condition, EE can be easily absorbed through skin as well as through the respiratory and alimentary tracts. It was mainly metabolized into 2-ethoxyacetal dehyde by alcohol dehydrogenase (ADH) and cytochrosome P450 2E1 (CYP450 2E1), and then 2-ethoxyacetal dehyde (EEA) was metabolized into 2-ethoxyethanol acid (EAA) by aldehyde dehydrogenase 2 (ALDiy and then was excreted outside of the body in the urine. The half time of EE is about 77 hours, so that it can be accumulated in the body easily.The hygiene and toxicology researchers in America , Japan and Germany, et al have identified that EE could cause reproductive and developmental toxicity, haematological and haematokinetical toxicity, kidney toxicity and neurotoxicity, among which reproductive and developmental toxicity is the most sensitive and more serious for the health impacts. At low concentration, decreased number and move ability of sperms, increased frequency of malformed sperms appeared. As the EE concentration increases, the toxicity of other systems began to appear. Now it has been proved by toxicological experiments that EAA is the active agent causing the reproductive and developmental toxicity. Since EE could be absorbed by multiplerouts, and EAA, with longer half time and able to accumulate easily, is the main metabolite, EAA is an appreciate biological exposure marker of EE.In order to keep the workers health, since 80s, many countries such as USA, Germany, et al have done a serial of toxicological and epidemiological research and recommended their own threshold limited value- time-weighted average (TLV-TWA) or threshold limited value - short time exposure level (TLV-STEL) for EE, according to their own different environment and situation. Having presided over a serial of animal experiments and epidemiological investigations, Gao Xing, et al, also proposed 18 mg/m3 as our country's TLV-TWA, which was almost the same with 5 ppm (equal to 18 mg/m3) recommended by the American conference of Governmental Industrial Hygienists(ACGIH). The two values were based on the adverse health effects on sperms, which was regarded as the most sensitive effects then. And what's more, 2-ethoxyethanol's BEIs recommended by ACGIH in 1998 is 100 mg/g Creatinine (Cr). However we haven't established it until now.From animal experiments or epidemiological data, it could be found that each individual had different concentration of EAA, sometime the concentrations have statistic differences, even if they were exposed to the same concentration of EE. Sakai et al studied the polymorphism of CYP2E1 and found EE with the genetic effects Maybe there were genotypes that were susceptible in the workers exposed to EE. But the genotypes of ALDH2, showed the polymorphism, in which at present there is no reports about the susceptible genotypes to EE.In order to make EE exposure assessment and health hazard evaluation, we chose the changes of sperms as the biological effect marker, calculated the relationship between long time exposure concentration and the concentration of metabolites, especially chose the genotypes of EE enzymes for the monitoring of the exposed group. The purpose was to establish the BEI of EE and at the same time to find out the influential factors, especially the effects of different genotypes of enzymes.2. Materials and methodsWe selected randomly three printing...
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