Antimicrobial Plastic

Some methods, based on standard disinfectant protocols, state a requirement for reduction of bacterial cells in a one hour period (e.g., a 2 log reduction - a 99% decrease in the number of viable bacteria). Others 

It is possible, however, that the eover slip eould eause the cell suspension to be artifieially depleted of oxygen, which will influence the survival or growth of the bacteria. To avoid anaerobie eonditions, a porous aeetate membrane filter can be used to eover the inoeulum. This modified technique is known as the membrane filter method. Recent work by the IBRG has, however, shown little influence on baeterial reeovery rates when varying the type of eover used. 

As with all antimierobial effect test methods, the pass and fail criteria are debatable. Log 2 (99%) reduction 

Membrane filter Cell suspension Test surface- 

Escherichia coli Log reduction (20 mins extrasion samples) 

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Packaging Technology and Science 16, No.6, Nov.-Dec.2003, p.223-9 PROPERTIES OF ANTIMICROBIAL PLASTICS CONTAINING TRADITIONAL FOOD PRESERVATIVES... 

Plastics Additives and Compounding 4,No.l2,Dec.2002, p. 18-21 ANTIMICROBIAL PLASTICS ADDITIVES TRENDS AND LATEST DEVELOPMENTS IN NORTH AMERICA Maikarian J... 

Patent Number US 6096800 A1 20000801 PROCESS FOR THE PREPARATION OF ANTIMICROBIAL PLASTICS Ottersbach P Hill F Hill F F Hill R L Anders C Huels AG... 

Antimicrobial compounds can be incorporated within plastics that are then molded into useful shapes. Instead of wearing off, as surface applications do with time, part wear just exposes new compound and renews the ability of the plastic to kill microbes on its surface (Alder, 2002). Antimicrobial plastics come in a variety of rod, plate, tube, and thin sheet shapes, and can be used for medical and food applications. 

US Registration Brings Global Status for Avecias s New Plastic Antimicrobial. Plastic Additives Compounding 2003, 5 (4), 8. 

Antimicrobials are incorporated into a plastic formulation to preserve the polymeric material by destroying or inhibiting the growth of microorganisms on the product s surface. The constant presence of a biocide on the surface of antimicrobial plastics is essential for successful inhibition of microorganisms. Antimicrobials should migrate to the surface at a rate sufficient to maintain an effective concentration of biocide at the surface. 

The key markets for quaternaries are as swimming pool algaecides and in cooling water appHcations (see Water, treatment of swimming pools, spas, AND HOTTUBs), which further explains their importance as process biocides rather than preservatives. Some uses in latex films and plastics have been claimed (14,15). Primary quaternary ammonium industrial antimicrobial agents and their producers are presented in Table 4. 

Another compound, the antimicrobial action of which is associated with chelation, is 2-pyridinethiol-A/-oxide [3811-73-2] (Omadine). Activity has been shown to depend on coordinating property. The iron chelate is active, but not the free pyridine compound (200). In the form of its zinc chelate it is found in shampoos to control seborrheic dermatitis (201). Other appHcations of this useful chemical include preservation of adhesives, plastics, latex paints, polyurethane foam, and metal working fluids (202). 

To be applicable in plastics the antimicrobial substances would not only have to be active against the requested microorganisms but they would also have to meet very specific requirements to show the desired effect in the final product ... 

Plastic and rubber additives are both commodity chemicals and specialties. The Handbook of Plastic and Rubber Additives [27] mentions over 13 000 products antioxidants and antiozonants amount to more than 1500 trade name products and chemicals [28], flame retardants to some 1000 chemicals [29] and antimicrobials to over 1200 products [30]. 

BHA, BHT, PG, TBHQ and tocopherols) a variety of stationary phases, mobile phases and detectors can be used [711]. Common antibacterials such as carba-dox, thiamphenicol, furazolidone, oxolinic acid, sul-fadimethoxine, sulfaquinoxaline, nalidixic and piromidic acid can be analysed by GE-RPLC-UV (at 254 nm). Collaborative studies have been reported for the HPLC determination of the antimicrobial sodium benzoate in aqueous solutions [712], Plastics devices used for field collection of water samples may contain polymer additives (such as resorcinol monobenzoate, 2,4-dihydroxybenzophenone or bisphenol A) or cyanobac-terial microcystins [713],... 

Direct Exposure In the event that an individual is at the scene of a known or suspected attack (e.g., white-powder letter, aerosol release, etc.), have them wash their hands and face thoroughly with antimicrobial soap and water as soon as possible. If antimicrobial soap is not available, use any available soap or shampoo. They should also blow their nose to remove any agent particles that may have been captured by nasal mucous. Remove all clothing and seal in a plastic bag. To avoid further exposure of the head, neck, and face to the agent, cut off potentially contaminated clothing that must be pulled over the head. Shower using copious amounts of antimicrobial soap (if available) and water. Ensure that the hair has been washed and rinsed to remove potentially trapped agent. The Centers for Disease Control and Prevention (CDC) does not recommend that individuals use bleach or other disinfectants on their skin. 

Tributyltin acetate, (C4H9)3SnOOCCH3, and bis(tributyltin) oxide, (C4H9)3Sn-0-Sn(C4H9>3, have been commercialized as antimicrobial agents in the paper, wood preservation, plastics and textile industries29. 

Plastics Additives and Compounding 3, No.12, Dec. 2001, p.12-5 ANTIMICROBIALS IN PLASTICS A GLOBAL REVIEW... 

Trends in the use of antimicrobials by the plastics industry are reviewed with details of the market by industry, region, types of antimicrobials used, and the industry s distribution system. Also identified are manufacturers and formulators. Regulations regarding the development for new biocides are examined, and expected growth of the global plastic antimicrobial industry is forecasted, together with details of key drivers for the growth. 

CEFIC has estimated that more than 60% of the 2,000 biocidal active ingredients and of the 20,000 formulated biocidal products containing them currently marketed in the EU may eventually be withdrawn as a result of the implementation of the Biocidal Products Directive. Avecia believes the BPD is likely to restrict new product development and increase the costs of notifying and listing active substances, meaning that research on new actives will be difficult to justify. Avecia Protection Hygiene develops and produces antimicrobials for more than 25 applications in industrial preservation, disinfection, plastics, textiles and personal care, and it continues to develop new products. 

Occlusive therapy Occlusive dressings such as a plastic wrap increase skin penetration by 10-fold. Discontinue the use of occlusive dressings if infection develops and institute appropriate antimicrobial therapy. 

Benzyl alcohol Antimicrobial preservative, disinfectant, solvent Oxidizing agents, strong acids, plastic containers, and methylcellulose... 

Chlorbutol Antimicrobial preservative, plasticizer (not oral) Plastic containers, rubber stoppers, carboxymethylcellulose, and Sorbate 80... 

Parabens are approved for use in oral solution and suspensions at a concentration of 0.015% to 0.2% w/v. Due to their low solubility, the sodium salts of parabens are often used in aqueous formulations. The parabens are most effective in the pH range of 2 to 6, and their antimicrobial activity decreases with increasing pH. Additionally, they are very unstable at pH 8 or above in solution. Methyl paraben has also demonstrated incompatibility with sorbitol and may show some discoloration in the presence of iron. The absorption of methylparaben by plastics has been reported with the amount absorbed being dependent upon the type of plastic and vehicle. However, no absorption has been reported for low density polyethylene (LDPE) or high density polyethylene (HDPE) containers. Certain coloring agents such as yellow iron oxide, ultramarine blue, and aluminum silicate can extensively absorb ethyl paraben in simple aqueous systems, thus reducing its preservative efficacy. 

Potassium sorbate has both antimicrobial and antifungal properties in formulations below pH 6. Generally, it is used at concentrations of 0.1% to 0.2% in oral formulations (solutions, syrup, and suspensions), and is used much more than sorbic acid because of its higher solubility and stability in water. However, some loss of antimicrobial activity occurs in the presence of nonionic surfactants and some plastics. 

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