Monday, July 12, 2010

Disinfectants as pesticides

Pest management professionals typically don't have to worry a lot about disinfectants.  Application of disinfectants is generally not part of the PMP's responsibilities; and in general the use of disinfectants is exempted from Texas (and most other states') pest control laws and regulations.  This makes sense, because daycare workers wiping down countertops, and nurses disinfecting hospital rooms and equipment, would otherwise have to have pest control licenses.

Nevertheless, questions about disinfectants frequently come up in discussion with the public.  Just the other day we were asked for input about the availability of "green" disinfectants for a public health clinic.  My school IPM colleague, Janet Hurley, provided a couple of excellent web links that I thought I would pass on in case you have an interest in learning more about the regulatory and scientific background of disinfectants.

If a customer asked, could you tell the difference between a sanitizer and a disinfectant?  Did you know that disinfectants don't kill all microorganisms?  It takes a sterilant to do that.  Sterilization processes typically rely on creating harsh physical or chemical conditions that kill all microorganisms, including tough bacterial spores and viruses.  To get a better understanding of these distinctions, Wikipedia provides an excellent introduction to disinfectants and related products.  The Wikipedia writers summarize the quandary of finding the ideal disinfectant well:
A perfect disinfectant would.. offer complete and full sterilization, without harming other forms of life, be inexpensive, and non-corrosive. Unfortunately, ideal disinfectants do not exist. Most disinfectants are also, by nature, potentially harmful (even toxic) to humans or animals. 
One of the things I learned from this article was that many household disinfectants contain Bitrex, an ingredient familiar to many of us in the pest control industry.  Bitrex is added to many rodenticides to make them highly distasteful to most pets and to humans.

The article explains why bleach remains one of the most cost-effective and efficient disinfectants.  But did you know that it's critical to never mix different kinds of indoor disinfectants, as many of them can interact and produce toxic byproducts?  Bleach, especially, should never be mixed with ammonia as it produces highly toxic ammonium chloride gas.  When using a bleach solution to clean areas that have been contaminated with pet or rodent urine one should always clean the surfaces with soapy water first to remove the ammonia components that might react with the bleach.

The Centers for Disease Control and Prevention (CDC) also maintains a site on the subject of disinfectants.  The focus of this article is on the regulatory framework affecting disinfectants and sterilants.  Lest we forget that germs are pests too, all disinfectants must be registered as pesticides with the U.S. EPA.  Look at the label of a bactericide product and you'll notice the EPA registration number, signal words, and precautionary statements similar to what we see on insecticide labels.

While the idea of using green cleaning products is good in many ways, we should not kid ourselves that there is always a perfectly safe way to do everything.  Most green cleaning products do not kill a wide variety of bacteria and cannot disinfect well, or sterilize.  However regular cleaning, good housekeeping and effective pest control can reduce the need for disinfectants by maintaining conditions that are not conducive to bacterial survival and multiplication.  And this is the best solution of all.

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