Comparison Of Toluene Levels Getting From Area Sampling And Personal Sampling

Toluene is a colorless, transparent liquid at room temperature, which has the aromatic odor similar to benzene. It is easy to volatile and soluble in benzene, alcohol, and most organic solvents. It is an important organic chemical raw material, mainly being used as a solvent and high-octane gasoline additive. Toluene can cause health hazards mainly through respiratory inhalation and skin absorption, while prolonged exposure to high concentrations may cause a variety of damage, for example, neurasthenic syndrome, hepatomegaly, women’s menstrual abnormalities, dry skin, chapped skin and dermatitis as well. Occupational toluene poisoning is the legal occupational disease in our country. In order to reduce and eliminate its occupational hazard, it’s important to control the workplace concentration of toluene. Currently, there are two occupational health standards about toluene, which are the time-weighted average permissible concentration (PC-TWA)50mg/m3and the exposure at permissible concentration (PC-STEL)100mg/m3.In China, Occupational health standards provide three kinds of occupational exposure limits, the maximum allowable concentration (MAC), the time weighted average allowable concentration (TWA), and the short-term exposure limit (STEL). Currently there are two sampling methods, which are area sampling and personal sampling. Both of them have advantages and disadvantages. The former is simple, time-saving and lower cost, but can’t accurately reflect the workers’actual exposure levels. The latter is complex-operating, time-consuming, higher cost, but can estimate the true level better.The present study used the "solvent desorption-gas chromatography" mehod to test the concentration of toluene in workplace. Results showed that the toluene concentration and its peak area are in a linear relationship within the range of17.3-866.9mg/L, with the detection limit of 1.2mg/m3(injection volume1μl) and the relative standard deviation (RSD) of0.95%, which meet the requirements of the workplace air monitoring study of toxic substances.In this study, exposure assessment of toluene exposed workers was made through collection of historical monitoring data, site investigations and sampling on a shoe factory in Shanghai. Data indicated that the workshop toluene concentration was positively skewed distribution.17main toluene positions were confirmed through the forms of conversation, questionnaires and site investigation. Continuous three days representative personal sampling and one-on-one area sampling were made. A regression equation (y=7.450+1.245x) was got from the fifty five paired data, in which "y" represented TWA levels of personal sampling, and "x" of area sampling. That equation can roughly estimate the toluene level in recent years.TWA results of the two methods were not correspond to each other.The area sampling results was higher than the personal sampling. The systematic errors of area sampling can be better interpreted and supplemented by the personal sampling. Therefore, the exposure assessment should adopt two sampling methods together in order to better assess the occupational hazards and provide a scientific basis for practical work. Furthermore, it is also confirmed that historical monitoring data can provide valuable reference.In addition, the choice of sampling method and test period, as well as the sample size and results of the calculation method may also affect the quality of exposure assessment.