Oxidative stress related to occupational exposure to toluene in workers from a plastic factory in Mexico City

Introduction
Is little what is known about toluene exposure in real occupational conditions. Most of investigations are from toluene´s abuse or animal models. Some of these studies have indicated that oxidative stress could have a crucial role in toluene´s toxicity mechanism. The aim of this study was to investigate the effects of toluene in antioxidant enzymatic mechanisms in workers occupationally exposed to toluene in a plastic factory in Mexico City.

Methods
This is a cross-sectional study of 56 male workers, in two groups, 25 exposed and 31 non- exposed to toluene at work. Hippuric-acid was determined in all exposed workers. Ceruloplasmine, gluthation-peroxidase (GPx) and superoxide-dismutase (SOD) were measured, the first one in all participants and the enzymes only in 20 samples. First, the antioxidant enzymes levels by group was analyzed and after that enzymes levels were co-related with the hippuric-acid level in the exposed group.

Results
Age, alcohol and tobacco consume, glucose, cholesterol and triglycerides levels were similar in both groups. Exposed group has a median hippuric-acid range from 0.34 to 0.69 g/g creatinine. No difference in antioxidant enzymes levels was found between groups. There was no correlation between hippuric-acid and ceruloplasmine or SOD, but it was positively correlated to GPx (R= 0.701, p≤0.05). Correlation between hippuric-acid and GPx remained after stratifying by confusion factors. The strongest correlation was observed in the youngest group. (R= 0.959, p≤0.01).

Discussion
Even that this study´s sample size is small, the correlation between hippuric-acid and GPx correlation magnitude is important and stays after stratified. It seems that GPx is the first antioxidant enzyme that responds to toluene occupational exposure.