Risk assessment, microbial contamination

The non- and mono-ortho CBs have been quantitated accurately in the principal source, namely, commercial PCB mixtures [15, 16] additional environmental sources such as incineration have been identified [17,18] their presence in every ecosystem including the pristine polar regions has been shown [19,20] estimates of their flux in air, water, soil, and the removal mechanisms such as OH reactions in atmosphere and sediment burial in rivers and oceans have been proposed [21] their microbial degradation and biotransformation in organisms have been studied [22,23] a battery of in-vitro and in-vivo bioassays using mammalian, avian, and piscian models for the benefit of risk-assessment of these CBs have been developed [24]. Studies like these in the last decade have resulted in a new awareness of these important class of industrial contaminants. 

Storage in a refrigerator Deep-freeze storage These measures reduce microbial contamination or prevent an increase in contamination during preparation and storage. For extemporaneous preparation of eye drops in pharmacies the responsible pharmacist must select the most adequate sterilisation technique after performing a risk assessment. 

The aim of this example of risk assessment is to assess the risks in order to prioritise measures to improve safety of reconstitution on the ICU ward [3]. Two hazards of reconstitution of parenteral medicines admixtures are focussed upon microbial contamination (in fact loss of sterility) and faulty composition. The probability of microbial contamination and faulty composition is related to the number of steps during the process that are critical for microbial contamination (see Sect. 31.3.2) or faulty composition respectively. The number of critical steps are multiplied by 2 if the medicine is mentioned in the Institute for Safe Medication Practices (ISMP) list of high-alert medications [4]. In this way the severity in case of faulty composition is taken into account. 

For prioritising actions both hazards (microbial contamination and faulty composition) were related to the frequency of administration. The top 10 of both frequency lists are taken into the risk assessment. The risk matrix puts the frequency of administration against the risk of contamination or the risk of faulty composition respectively (= Tables 21.4 and 21.5). These matrixes visualise which products have to be improved first. Risk reduction can be achieved by decreasing the number of steps, for example by pharmacy preparation of premixed preparations or prefilled syringes. 

Van Beelen, P. Doehnann, P. Significance and apphcation of microbial toxicity tests in assessing ecotoxicological risks of contaminants in soil and sediment. Chemosphere 1997, 34, 455-499. 

---