Bed Bugs, Propoxur and the EPA
Some thoughts on the national discussion happening around a recently banned pesticide.
In 1996, the pesticide Propoxur was one among a number of chemical pesticides that were placed under stronger use restrictions due to new information on its potential health impacts. In 2007, the Environmental Protection Agency enacted a full ban on the in-home use of Propoxur, although it can still be found as an active ingredient in some brands of flea collars.
Now, seeing Propoxur as the answer to their bed bug woes, many communities have pressured the EPA to temporarily lift its ban on the chemical so that it may be applied legally. While there are some 25 states in favor of this idea, the State of Ohio has led the charge, beginning with an initial petition to the EPA in November of 2009 and then with a letter sent by Governor Ted Strickland to Lisa Jackson in April of 2010.
The EPA responded in June saying that the ban on Propoxur would not be lifted due to the fact that it would pose "unacceptable risk(s) to children who might be exposed to propoxur in and around rooms treated for bed bugs." Subsequently, the EPA received considerable criticism from state and local authorities who desire to use the chemical, as well as from pest control providers and industry leaders who clearly stand to benefit from its reintroduction to the marketplace. Citing bed bugs’ resistance to the available chemical insecticides, more than one angry editorial has gone as far as to say that the EPA itself is responsible for the 2010 bedbug rebound due to comparable bans on “more effective” pesticides stretching all the way back to DDT.
There are numerous important topics here that need to be addressed:
- What's the deal with Propoxur?
- What about pest resistance to pesticides?
- Is the EPA to blame for bed bugs?
- What does it mean to "ban" a pesticide?
A good place to start is with a look at Propoxur and the reasons why it was restricted in the first place.
Propoxur is a carbamate insecticide that works by disrupting the target's ability to make and process the enzyme cholinesterase. Cholinesterase is essential to nervous system function. For bugs, when this enzyme is blocked, the result is rapid paralysis followed by death. Add to this the fact that Propoxur can have an extended impact on indoor areas where it is applied, killing bugs that come into contact with it long after the chemical spray has dried, and you can understand why it has a reputation for being especially effective.
Propoxur was introduced about fifty years ago, and has been used in domestic, urban, agricultural and even aquatic settings. Testing shows that it is moderately toxic to fish, highly toxic to birds (differing somewhat across species) and invariably toxic to honeybees which are already suffering a decline. Propoxur is also acutely toxic to people, and is made more dangerous by the fact that it can be absorbed through the skin. This characteristic, paired with its ability to persist in indoor environments, makes exposure a very realistic possibility for children and pets.
Clinical toxicology studies conducted in the early 1980s found that exposure to Propoxur results in cholinesterase-inhibiting effects in people, and these are not pretty. Common symptoms include abdominal cramps, nausea, vomiting and/or diarrhea, incontinence, excessive sweating and/or salivating, blurred vision, disorientation, difficulty breathing, and hypertension (high blood pressure). While these ailments are short lived in many cases, there are recorded instances in which exposure to Propoxur has actually resulted in organ tissue damage. This is why the EPA finally banned it from in-home use in 2007, and why it has decided to maintain that ban now in the midst of bed bug worries.
Their reasoning holds up. While bed bugs are unquestionably miserable, they transmit no diseases and therefore do not constitute a health threat greater than that posed by Propoxur itself. This is not meant to marginalize the havoc that bed bugs can wreak in a home, or to say that anyone should be denied the tools they need to protect themselves from infestations; it is simply to say that if one seeks ultimately to preserve their own health and comfort, then the use of Propoxur would be counterproductive even if it were legal. There are simply better and safer ways to treat infestations. The link at the bottom offers some of those.
On the issue of bed bugs showing resistance to other pesticides...
When a species develops tolerance to a given pesticide, it is a signal that the pesticide has been overused. This is symptomatic of a general overreliance on pesticides as a form of control. Unfortunately, the common reaction too often involves simply switching to a different chemical, which is then replaced when it becomes ineffective, and so on. This cycle has been termed the pesticide treadmill by some. Because the cycle serves to highlight the long-term inability of chemicals to deal with target organisms, it fails to justify lifting a ban on any chemical, much less one like Propoxur. If anything, the ineffectiveness of current chemical treatments should be taken as evidence of the need for a new approach to managing these infestations, one based on common sense methods that work by eliminating the conditions which allow infestations to occur in the first place.
Given how widely remembered it is that bed bugs began showing resilience in the face of DDT before it was banned in 1972, the current bed bug surge cannot be blamed on the EPA for protecting the public and the greater environment from DDT and other awful things, i.e. doing its job. Rather, this surge is the result of insect populations adapting for survival in spite of the various challenges we throw at them. If the EPA can be faulted for anything in relation to bed bugs, it could be for not emphasizing preventative strategies publicly enough or for turning too quickly to new chemical strategies before experimenting with better integrated pest management (IPM) methods.
Finally, there is the question of what it means to ban a pesticide from use.
Does it constitute a ban to say, “We are no longer going to use this pesticide…unless, of course, we really need to?” The answer is no, not really. Had the EPA reversed its position on Propoxur, this is precisely the message it would've sent. Thankfully, this hasn't happened.
Banning specific pesticides from use, while symbolically valuable, is not the best strategy for actually reducing overall pesticide use. It is too easy for a banned chemical to be replaced by a legal one that’s just as bad. In fact, this phenomenon has undermined many a diligent effort in the arena of pesticide reform. However, if bans could be lifted simply out of convenience, then they would be truly meaningless as they would no longer hold even any symbolic value. Those governments, industries and individuals calling for a lift of the Propoxur ban are calling for a step backward when they should be employing alternatives to take a step forward.