Biocides, chemical

Denyer S.P. Hugo W.B. eds) 99l) Mechanisms ofAction of Chemical Biocides. Society for Applied Bacteriology Technical Series No. 27. Oxford Blackwell Scientific Publications. 

Magulski, T., Pauhnann, D., Bischoff, B., Becker, B., Steinmann, E., Steinmann, J., Goroncy-Bermes, P., and Steinmann, J. (2009). Inactivation of murine norovirus by chemical biocides on stainless steel. BMC Infect. Dis. 9,107. 

THE FUTURE PROSPECTS FOR CHEMICAL BIOCIDES FOR POOL WATER TREATMENT... 

The results of recent trials conducted at the Cranfield University pilot-scale swimming pool are also presented. This research is based largely on chlorination using hypochlorite, but includes other technologies. Results give a clear indication of the extent to which chlorinated byproducts within the swimming pool, as well as the relative levels of DBPs formed between bromination and chlorination. The implications of this research on the future of the use of chemical biocides in swimming pools is considered. 

Examples Chemicals Biocides Cleaners Additives etc. Examples Structural materials Foodstuffs Plastics Durable goods... 

Table 1 Some Common Neutralizers for Chemical Biocides...

Times change, and today almost all of the raw material chemicals, biocide concentrates, phosphonates, and specialty polymers that can be used in modem water treatment formulations are widely available to both large and small companies. Most water treatment companies around the world have potential access to these materials. 

Specialities Photographic Chemicals Dyes and Pigments Perfumes and Fragrances Adhesives Coatings Food Additives Electronic Chemicals Biocides Nanotechnology... 

As management of legislation on consumer and industrial chemicals, biocides and plant protection products has much in common, countries may find it advantageous to aspire to a high degree of co-ordination between these areas. 

Qualified scientific assessments of hazards and risks can be made by scientific institutions at universities or institutes contracted to provide assistance. As hazard and risk assessments of, for example, industrial chemicals, consumer chemicals, biocides and plant protection products have much in common, it would be cost efficient to co-ordinate and concentrate scientific support in order to avoid a thinning out of resources and expertise. 

Table 2.7 Toxicology testing recommendations for food contact substances based on dietary concentration (EXT) and corresponding estimated daily intake (EDI) values. Note that the cumulative exposures are based on non-biocidal chemicals biocidal tiers are one-fifth the cumulative dietary concentration (CDC) and cumulative estimated daily intake (CEDI) values expressed. DC and CDC values are in units of mass of migrant per mass food consumed. EDI and CEDI values are in units of mass of migrant per person per day. Abbreviations are as follows p,g (microgram), kg (kilogram), mg (milligram), < (less than or equal to), < (less than), > (greater than), and > (greater than or equal to)...

Table 7.1 Toxicology testing recommendations for food contact substances based on dietary concentration (DC) and corresponding estimated daily intake (EDI) values. Note that the cumulative exposures are based on non-biocidal chemicals biocidal tiers are one-fifth the cumulative dietary concentration (CDC) and cumulative estimated daily intake (CEDI) values expressed...

Biocides are used widely in industry. There are at least three main classes of industrial chemical biocides. The first class includes the oxidizing and bleaching agents, such as chlorine dioxide, hydrogen peroxide, and sodium hypochlorite. The oxidizing action may directly kill bacteria or fungi or weaken the cell walls so that they are more susceptible to other classes of biocides (see below). Sodium... 

A second class of industrial chemical biocides involves highly toxic organic chemicals. Subclasses of toxic biocides include thiazoles, thiocyanates, isothiazolins, cyanobutane, dithiocarbamate, thione, and bromo-compounds. As the names imply, many of the toxic biocides contain sulfur ( thio -). 

A third class of industrial chemical biocides consists of agents with the ability to inhibit biological film formation, also called surfactants . The term surfactant originates from the phrase surface active agent. Surfactants fall into four broad categories anionic (e.g., soaps, alkyl benzenesulfonates, alkyl sulfonates, alkyl phosphates), cationic (e.g., quaternary ammonium salts), nonionic (e.g., alkyl polyglycosides, alcohol ethoxylates, alkylphenol ethoxylates), and zwitterionic. 

New EU directives may limit the development and application of new biocides and for this reason, and concerns on toxicity or pollution, there is interest in alternative water treatment techniques such as ultrasound, high-pressure vortexing and electro-coagulation. These may also be used where chemical treatment is not appropriate. ATP measurements are likely to prove useful to monitor the effectiveness of these types of treatment but as with chemical biocidal treatment the nature of the ATP results may depend on the mode of action. One type of electrochemical treatment has been evaluated in our laboratory. The results indicate that as with chemical biocide treatment the use of both Total and Free ATP measurements can be of value in the interpretation of the results, monitoring the process efficacy and in optimisation of this method of water treatment. 

Effect of Thermal and Chemical Biocide Treatments of Soil on Enhanced Microbial Activity... 

Biofouling is a major economic and management problem for the aquaculture industry which been managed in the past by the use of toxic chemicals (biocide) that have had serious environmental repercussions (Me Cloy and De Nys, 2000). 

Essential oils are active in the inhibition of Gram positive and Gram negative bacteria, yeast, and fungi. These oils usually show weak to moderate activity when compared with chemical biocides such as antibiotics, quaternary ammonium salts, or chlorinated phenols such as triclosan. When the major components are isolated, they usually show improved activity compared to the essential oils. The test methods employed commonly determine inhibition activity via an MIC, but do not usually address the issue of MLC (minimum lethal concentration) or how quickly viable organisms are reduced over a short period of time. In order to determine this, other test methods need to be employed. Differences in... 

SM Bloomfield. Methods of assessing antimicrobial activity. In SP Denyer, WB Hugo, eds. Mechanism of Action of Chemical Biocides Their Study and Exploitation. Cambridge, MA Blackwell Scientific Publications, Inc., 1991, pp. 1-22. 

The process of sterilisation is required for any product used in a situation where there is a risk of infection. Sterilisation requires the application of a chemical (biocide) to a product, or the physical removal of micro-organisms from the product. The objective is to kill the bacteria, the definition of bacterial death being the irreversible loss of reproductive ability. There are a number of chemical and physical methods available to achieve this objective. The physical methods... 

Like all chemicals, biocides too have pros and cons. Knowing these pros and cons is important in the sense that apart from general considerations that must be given to the evaluation of biocides (such as being broad spectrum or compatible with environmental requirements), the operators need to know under what conditions they can have what opportunities. Below, the pros and cons of some oxidizing and nonoxidizing biocides are given. 

---