SIMPLE METHODS FOR DETERMINING
POTENT XENOBIOTICS IN WATER AND FOODSTUFFS
There is great interest in the impact of long term exposure in humans and wildlife to trace concentrations of potent biochemicals derived from human activities [1,2]. This stems from emerging information that even at trace levels in drinking water and foodstuffs key contaminants may induce adverse physiological effects. Of prime concern are traces of estrogens, which can lead to feminisation of males, mutagens, which can induce cancer and antibiotics, which may lead to the induction of resistance in bacteria.
Renewed interest in estrogens in the environment has stemmed from observations that inactive non-estrogenic steroid metabolites excreted from humans and wildlife and excreted into sewers are converted into potent active forms by the bacteria in sewage sludge [3,4]. Several reports from studies across the world have established that total estrogenic activity as assessed by receptor assay screening is typically of the order 1-10 ng/l [5,6] and that phenolic xenoestrogens such as 4-nonylphenol only contribute less than 5% of this estrogenic activity .
Recent monitoring of sewage treatment plant effluents and river water has demonstrated the presence of up to 18 antibiotic substances. One of the most frequently observed drugs was sulfamethoxazole with concentrations up to 6 mg/l although beta-lactam antibiotics such as penicillins could also be detected at lower concentrations (20 ng/l) . Other studies have identified Acinetobacter isolates from sewage, freshwater aquaculture habitats, trout intestinal contents and frozen shrimps and reported that those from sewage were more resistant to microbial agents than isolates from other sample types [9,10] thus indicating a possible link between the presence of antibiotics in sewage water and induced microbial resistance.
Antineoplastics are used as anticancer agents. Patents excrete them into the sewage and they are not degraded in municipal treatment plants and therefore can be detected in their effluents . Such compounds are also carcinogenic, tetratogenic, fetotoxic and mutagenic. Other mutagenic compounds reported in sewage water and soil are the heterocyclic amines and polyaromatic hydrocarbons derived from smoke and diesel exhaust. They are also present in very low concentrations (low parts per billion or less) .
Typical levels reported for these analytes in water are ng-mg/l and consequently current methods for their detection and quantitfication require laborious extraction and pre-concentration steps prior to analysis and the analytical methods are themselves slow requiring expensive and sophisticated equipment.
The current major method of extraction and preconcentration is by solid phase extraction and a variety of analytical approaches have been adopted, the most common being chromatography coupled to mass spectrometry such as GC-MS and LC-MS although immunoassay such as ELISA has also found favour [8,12]. The net result is that extraction and analysis are performed at a dedicated laboratories and results are obtained days after the samples are taken. If extensive sampling and analysis are to be performed to extend our knowledge of the prevalence, distribution and levels of such contaminants then simpler more cost effective yet robust systems are needed that retain the sensitivity of current methods.
Much attention is therefore being devoted to exploring alternative methods for the simple extraction and analysis of such key contaminants. This proposal explores one approach that uses immobilized antibodies for the extraction process and compares simple dip strip devices and optical biosensors for subsequent analysis. Mutagenicity will be assessed using an electrochemical biosensor. A successful outcome will identify a simple method suitable for analyte extraction from food and beverages and specify simple and robust methods for their subsequent analysis.
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