Iodine-based disinfectants

Although iodine-based disinfectants (iodofors) have been used for many years, there has until recently been little or no attention paid to promoting commercial iodine-based products for cooling systems. One or two different products were introduced during the early to middle 1990s into certain markets, such as Australia and the United Kingdom. 

Iodine is extensively used in a variety of forms as both an antiseptic and a disinfectant. lodophors, usually nonionic surfactants (qv) complexed with iodine, were developed for more readily usable iodine-based antiseptics and disinfectants. These are used as disinfectants in dairies, laboratories, and food processing (qv) plants, and for sanitation of dishes in restaurants. The reaction product of lanolin and iodine shows utiHty as a germicide (149). 

The interhalogen compounds are the bromine- and iodine-base materials. It is the larger, more positive halogen that is the reactive portion of the interhalogen molecule during the disinfection process. Although only used on a limited basis at present, there are members of this class that show great promise as environmentally safe disinfectants. 

Polyether compounds form stable adducts with iodine, a property which has led to their use as iodophores for bactericides on human and animal skin. For medical applications, iodide concentration is kept low, since the triiodide ion has little disinfecting activity compared to iodine. By contrast, iodine-based analytical methods for surfactant determination are usually conducted in the presence of a large excess of pxjtassium iodide. The likely mechanism consists of the K" -p)olyether complex associating with the large, lipophilic, triiodide anion. The absorbance maximum of the complex is shifted from that of triiodide... 

The most widely used and effective disinfectant solutions are based on iodine (iodophor) with concentrations ranging between 0.05% and 0.1%, but sometimes higher concentrations are recommended. Other agents such as chlorhexidine or chlorine dioxide, peroxide, sodium chloride and lactic acid may also be effective (Wilson et al., 1997) but are not common. Recent trials show positive effects of aloe vera-based dipping agents (Leon et al., 2004). One problem of iodine containing products is their low pH value (<4.0), which is necessary for their antimicrobial activity (Hansen and Hamann, 2003). 

It is widely employed as a disinfectant in medicine (Povidone-iodine) because of its mildness, low toxicity, and water solubility. In actuality, the complex is based on HI3 since HI is formed in situ from iodine during the manufacturing process (96). According to the US. Pharmacopeia, Povidone-iodine is a free-flowing, brown powder that contains from 9—12% available iodine. It is soluble in water and lower alcohols. When dissolved in water, the uncomplexed free iodine level is very low (Fig. 4) (97) however, the complexed iodine acts as a reservoir and by equiUbrium replenishes the free iodine to the equilibrium level. This prevents free iodine from being deactivated because the free form is continually available at effective biocidal levels from this large reservoir (98). The structure of the complex has been studied and in essence is similar to the representation above (98,99). PVP will interact with other small anions and resembles semm albumin and other proteins in this regard (100). It can be "salted in" with anions such as NaSCN or "out" with Ns SC much like water-soluble proteins (101). 

Because microorganisms are airborne, laboratory surfaces should be sterilized prior to beginning work. To do this, there are many aerosol disinfectants available that are simply sprayed onto the area and wiped away. Some laboratories rely on solutions of chlorine (bleach) to assist in maintaining a sterile environment. Although ultraviolet light can be used as a surface sterilant, most laboratories rely on wiping down the area with a liquid disinfectant (Table 13.3). Several disinfectants that find application in the winery (Chapter 9) can also be used in a laboratory such as iodine or QUATS. Other laboratory disinfectants are the phenol-based formulations like o-phenylphenol (Lysol ) and hexachlorophene (PhisoHex ). 

Endocrine Hypothyroidism and altered metabolism of thyroid hormones have been reported as adverse events in neonates and children, resulting from the use of antiseptics containing povidone-iodine [SED-15, 1896 SEDA-30, 279 SEDA-31, 411 SEDA-32, 440]. Because of concerns about possible iodine excess, chlorhexidine-based antiseptics have replaced povidone-iodine in some clinical settings. However, this may not be advantageous for infants and children who are receiving total parenteral nutrition (TPN) as iodine is not routinely added to TPN solutions. Previously, iodine deficiency was considered unlikely in patients receiving TPN, because of adsorption from iodine-containing skin disinfectants and other adventitious sources [67 68 ]. 

Not only disinfectants but also over-the-counter drugs containing large concentrations of iodine may cause thyroid dysfunction [74 ]. Based on two cases of transient hypothyroidism in response to single, short-term exposure to topical iodine in premature infants, monitoring of the thyroid function in premature infants after iodine treatment was recommended [75 ]. 

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