Monitoring Of Chemical Substances Research Articles

Occurrence of 1153 organic micropollutants in the aquatic environment of Vietnam.

The rapid increase in the number and volume of chemical substances being used in modern society has been accompanied by a large number of potentially hazardous chemicals being found in environmental samples. In Vietnam, the monitoring of chemical substances is mainly limited to a small number of known pollutants in spite of rapid economic growth and urbanization, and there is an urgent need to examine a large number of chemicals to prevent impacts from expanding environmental pollution. However, it is difficult to analyze a large number of chemicals using existing methods, because they are time consuming and expensive. In the present study, we determined 1153 substances to grasp a pollution picture of microcontaminants in the aquatic environment. To achieve this objective, we have used two comprehensive analytical methods: (1) solid-phase extraction (SPE) and LC-TOF-MS analysis, and (2) SPE and GC-MS analysis. We collected 42 samples from northern (the Red River and Hanoi), central (Hue and Danang), and southern (Ho Chi Minh City and Saigon-Dongnai River) Vietnam. One hundred and sixty-five compounds were detected at least once. The compounds detected most frequently (>40% samples) at μg/L concentrations were sterols (cholesterol, beta-sitosterol, stigmasterol, coprostanol), phthalates (bis(2-ethylhexyl) phthalate and di-n-butyl phthalate), and pharmaceutical and personal care products (caffeine, metformin). These contaminants were detected at almost the same detection frequency as in developed countries. The results reveal that surface waters in Vietnam, particularly in the center of large cities, are polluted by a large number of organic micropollutants, with households and business activities as the major sources. In addition, risk quotients (MEC/PNEC values) for nonylphenol, sulfamethoxazole, ampicillin, acetaminophen, erythromycin and clarithromycin were higher than 1, which indicates a possibility of adverse effects on aquatic ecosystems.

Dataset from chemical gas sensor array in turbulent wind tunnel.

The dataset includes the acquired time series of a chemical detection platform exposed to different gas conditions in a turbulent wind tunnel. The chemo-sensory elements were sampling directly the environment. In contrast to traditional approaches that include measurement chambers, open sampling systems are sensitive to dispersion mechanisms of gaseous chemical analytes, namely diffusion, turbulence, and advection, making the identification and monitoring of chemical substances more challenging.The sensing platform included 72 metal-oxide gas sensors that were positioned at 6 different locations of the wind tunnel. At each location, 10 distinct chemical gases were released in the wind tunnel, the sensors were evaluated at 5 different operating temperatures, and 3 different wind speeds were generated in the wind tunnel to induce different levels of turbulence. Moreover, each configuration was repeated 20 times, yielding a dataset of 18,000 measurements. The dataset was collected over a period of 16 months.The data is related to “On the performance of gas sensor arrays in open sampling systems using Inhibitory Support Vector Machines”, by Vergara et al.[1].The dataset can be accessed publicly at the UCI repository upon citation of [1]: http://archive.ics.uci.edu/ml/datasets/Gas+sensor+arrays+in+open+sampling+settings

A Survey on Chemical Hazards and Liver Function in Rubber Industry Workers in Iran

Rubber industries workers are at risk of hepatic dysfunction from exposure to rubber dust and a mixture of different hydrocarbons. This study aimed to evaluate the relation between chemical hazards in workplace and serum hepatic transaminases in rubber industry workers in Iran. This historical cohort study was conducted in a rubber-manufacturing industry in Mashhad. It con-sisted of 91 workers with chemical substances exposure and 85 workers not exposed to chemicals. Hepatic transaminases including alanine transaminase (ALT) and aspartate transaminase (AST) were compared between these two groups. Required data were collected through questionnaire, liver enzymes evaluation, and environmental monitoring of chemical substances. The data were analyzed with SPSS 11.5. A total of 176 workers enrolled in this study included 113 (64.2%) male and 73 (35.8%) female. The mean of age and employment duration in exposed group were 29.22 ± 3.99 and 5.41 ± 2.77 and in non-exposed group were 30.33 ± 4.11 and 5.29 ± 2.77 respectively. The mean of ALT in exposed and non-exposed groups was 31.3 ± 8.04 and 23.8 ± 10.42 (p = 0.01) and the mean of AST was 29.6 ± 9.7 and 27.3 ± 8.2 (p = 0.1) respectively. A significant difference was shown between mean of ALT at the date of employment and at the time of the study in exposed group. According to our findings evaluation of serum transaminases is a useful screening method which might be beneficial in early detection of hepatocellular injuries in rubber industry workers.

Analysis in workplace surveillance

The protection of the health against effects of chemical substances which are taken up at the workplace is controlled in Germany by the Gefahrstoffverordnung (Hazardous Substances Ordinance). The protection is based on the adherence to threshold limit values for the concentration of the toxic substance in the air or in body fluids of the human being. The adherence to the Maximum Concentrations at the Workplace (MAK) and the Technical Exposure Limits (TRK) for carcinogenic substances in the air of workplaces is achieved by the continuous measurement of the toxic substance in the air at the workplaces (ambient monitoring). The continuous monitoring of chemical substances and their metabolic products in blood and urine (biological monitoring) guarantees that the Biological Tolerance Values for Working Materials (BAT) and the Exposure Equivalents for Carcinogenic Working Materials (EKA) are adhered to. Ambient monitoring and biological monitoring complement each other with regard to the desired health protection of the individual. The possibilities of modern instrumental analysis guarantee today that practically all toxic substances in the air can be quantitatively determined. As intercomparison programmes show, a lot more could be done concerning the analytical reliability of air analyses. The introduction of laboratory-internal and -external quality control in the laboratory analysing air therefore seems to be of urgent necessity. The accrediting of laboratories and the use of reliable analysis procedures alone is not sufficient to guarantee the analytical reliability of the results. By means of biological monitoring today very many toxic substances in blood and urine can be routinely determined. An effective quality control prescribed by the Hazardous Substances Ordinance allows reliable analysis results up to the ppt-range. Certain groups of substances, such as e.g. many pesticides, are today still beyond the possibilities of biological monitoring. Increasingly methods are being developed which enable the influence of toxic substances on the human body to be quantified. The adducts of carcinogenic working materials at the germ plasm (DNA) or at the haemoglobin open up new perspectives.

Chemical Sensors (1)

The field of chemical sensors has grown rapidly in the past decade. Various types of chemical sensors have been devised for the detection and monitoring of chemical substances contained in gases, solutions, and organisms. Besides the basic researches on sensing mechanism, selectivites, sensitivities and so on, efforts have also been directed to searches for new sensor materials as well as to finding new application fields. The chemical sensor is a combination of a receptor portion for molecule recognition and a transducer portion for electrical signal output. In order to enhance the selectivity, molecular shape-selective function is required for the receptor. As for the transducer, there are two major methods to detect electrical signal, that is, amperometry and potentiometry. In both cases, it is very important to perceive the relation of output signal to the concentration of molecule to be recognized. This paper reviews recent advances in chemical sensors, including their principle and characteristics, and refers to some future scopes.