DeltaGard, deltamethrin

In the past, Chester County has sprayed pyrethrin in an effort to attack mosquitoes. No chemical pesticide is selective; a poison that kills adult mosquitoes will inevitably affect other forms of life. (Biological agents such as larvicides are much more selective.)

Now the County seems to have gone over to another member of the pyrethroid chemical group, DeltaGard, whose active ingredient is deltamethrin.

The information below is mainly about the DeltaGard variant for use in gardens and landscaping, which has the same active ingredient as the DeltaGard insecticide used against mosquitoes. For more on the mosquito spray, see here.

What’s deltamethrin? Of course, the industry doesn’t think it’s dangerous. Some other sources beg to differ. A relatively recent post in Chemicals.News (no friend to the chemical industry) says:

“Deltamethrin — toxicity, side effects, diseases and environmental impacts”

12/05/2017 / By Rita Winters

Deltamethrin is a pyrethroid insecticide that is registered for use in commercial, agricultural, and residential areas. It plays a role in controlling malaria and targets other insects like cockroaches, spiders, ants, fleas, silverfish, bed bugs, bird mites, house flies, and beetles. Deltamethrin products are one of the most popular and widely used pesticides in the world and are very popular with government pest control operations in the country. It is highly toxic to the environment, especially to aquatic life forms like fish and crustaceans. Deltamethrin is also known to be toxic to humans. As a neurotoxin, it attacks the nervous system and causes a variety of negative side effects and fatality. In 2011, a Japanese woman ingested large doses of pesticides that contained deltamethrin, which resulted in motor neuron death.

This chemical compound acts by blocking the closure of the ion gates of sodium channels during repolarization. It then disrupts the transmission of nerve-related impulses causing depolarization of the nerve cell membranes. It is very effective on insects, especially those considered as pests. However, it also affects beneficial insects including honey bees….

read more at Chemicals.News

According to the National Pesticide Information Center: “While children may be especially sensitive to pesticides compared to adults, it is currently unknown whether children have increased sensitivity specifically to deltamethrin….” (Parents will not wish to experiment to find out.)

Also: “When deltamethrin gets in the soil, it has a tendency to bind tightly to soil particles. It has a half-life ranging from 5.7- 209 days. Half-life is the measure of time it takes for half of the applied amount to break down…. Deltamethrin has a half-life of 5.9-17 days on plant surfaces. It is unlikely to be taken up by plants, since it binds to soil particles so tightly….” (So that could be reassuring if you are out for a walk in the street, but not so much if you’d like to consume your own organic produce or turn over your garden knowing that may have pesticide residue in it for up to 7 months.)

“NPIC provides objective, science-based information about pesticides and pesticide-related topics to enable people to make informed decisions. NPIC is a cooperative agreement between Oregon State University and the U.S. Environmental Protection Agency.” Download the pdf of its deltamethrin report here: Deltamethrin General Fact Sheet

See some other sources at these sites:!po=76.0417

Deltamethrin molecule
The manufacturer’s label (download here: deltagard-5sc-label ornamental) contains an immense list of insects as well as spiders that DeltaGard kills when used on lawns and landscaping. The list includes ants, caterpillars, crickets and grasshoppers, among others that most of us might not see as pests but as important members of the environment; and many of the target species are important food sources for birds, amphibians, and reptiles.

And that is just for the supposed pests. Of course they don’t list the other species than can be killed, such as adult butterflies and dragonflies.

And the label says, not reassuringly for those of us with home gardens:

“DO NOT apply this product to edible crops.”

If you want further non-reassurance, download the manufacturer’s Safety Data Sheet relevant to mosquito spraying here: DeltaGard_Insecticide, including statements such as:

“This product contains material which are Trade Secret and may have Occupational Exposure Limits.”

“Do not allow to get into surface water, drains and ground water.”


Risk analysis needed before spraying permethrin

Contributed by one of Dontsprayme’s consulting scientists, in response to spraying activity this summer

I am concerned about the recent decision to spray in an area of Chester County for West Nile carrying mosquitoes, considering what is currently known about permethrin, the availability of less toxic alternatives and methods for mosquito control, and the demonstrated resistance of mosquito populations to this pesticide. Even if there are some West Nile positive mosquitoes in the vicinity, has a risk analysis been done to see that the perceived benefits of spraying outweigh the long term risk to human health?

While permethrin was studied at length in 1994 by the US Army and found to be relatively safe, this early study should be taken in context: more American soldiers have died from insect-borne illness than of enemy fire. For troops deploying to tropical areas, and who have already willingly put their lives on the line for our country, permethrin is the lesser of two evils. Since the 1994 study, there has been a great deal of research into the toxicity of permethrin, and the picture grows more and more grim with the passing years. Work that supports the use of permethrin, such as the EPA’s cumulative risk assessment (2011)[1], is very thorough at the surface, but consider limited endpoints: specifically, those derived from the a priori known ways in which pyrethrins and pyrethroids disrupt neural function.

As complete as the EPA study seems to be, its flaw is in its failure to consider other endpoints besides neural function. A recent review article[2] identified 29 studies in which permethrin-induced toxicity was identified in various species (and cited a number of other studies where human toxicity was shown). It also goes into far more detail than the Army study about the mechanisms of toxicity in the various bodily systems.

From the article:

Although it was believed that PER showed low mammalian toxicity, an increasing number of studies have shown that PER can also cause a variety of toxicities in animals and humans, such as neurotoxicity (Carloni et al., 2012, 2013; Falcioni et al., 2010; Gabbianelli et al., 2009b; Nasuti et al., 2014, 2008, 2007b), immunotoxicity (Gabbianelli et al., 2009a; Jin et al., 2010; Olgun and Misra, 2006), cardiotoxicity (Vadhana et al., 2010, 2011a, 2011b, 2013), hepatotoxicity (Gabbianelli et al., 2004, 2013), reproductive (Issam et al., 2011), genotoxic (Turkez and Aydin, 2012, 2013; Turkez and Togar, 2011; Turkez et al., 2012), and haematotoxic (Nasuti et al., 2003) effects, digestive system toxicity (Mahmoud et al., 2012; Sellami et al., 2014b, 2015), anti-androgenic activity (Christen et al., 2014; Xu et al., 2008), fetotoxicity (Erkmen, 2015), and cytotoxicity (Hu et al., 2010) in vertebrates and invertebrates.

Additionally (Vadhana et al., 2013):

Early life environmental exposure to PER could play a critical role in the onset of age-related diseases (Carloni et al., 2012, 2013; Fedeli et al., 2013; Gabbianelli et al., 2013; Vadhana et al., 2011b). Previous findings demonstrate that early life pesticide exposure to low doses of the PER insecticide has long-term consequences leading to toxic effects such as cardiac hypotrophy, increased Ca2 ©≠ level and increased Nrf2 gene expression….

In fact, there is evidence that effects of this nature are transgenerational and that there are epigenetic changes that ensue due to exposure. What’s clear is that the pesticide research community has NOT signed off on the harmlessness of such pesticides to humans despite the EPA guidelines or material safety data sheets. 

In addition its toxicity, it’s also fairly clear that mosquitoes evolve resistance to permethrin and other pesticides relatively rapidly. From Ramkumar et al (2015), after exposure to permethrin, within 10 generations, the 50% lethal dose concentration (LC50) of permethrin increased 17-fold. 

Ramkumar, G., & Shivakumar, M. S. (2015). Laboratory development of permethrin resistance and cross-resistance pattern of Culex quinquefasciatus to other insecticides. Parasitology Research, 114(7), 2553–2560.

Research on West Nile carrying mosquitoes indicates that when field collected mosquitos were tested for pesticide resistance, in one case there was a 299-fold increase in dosage to reach the LC50.

Kasai, S., Shono, T., Komagata, O., Tsuda, Y., Kobayashi, M., Motoki, M., … Tomita, T. (2007). Insecticide resistance in potential vector mosquitoes for West Nile virus in Japan. Journal of Medical Entomology, 44(5), 822–829.

An alternative to using such pesticides is a larvicide, BT, which has been studied extensively. This appears to be safe at the moment (except for mega-doses, or deviant genetic strains), and is a champ at killing mosquito larvae. 

Ibrahim, M. A., Griko, N., Junker, M., & Bulla, L. A. (2010). Bacillus thuringiensis. Bioengineered Bugs, 1(1), 31–50.

So the question is: if permethrin has already been shown to be dangerous to animals and humans AND it’s been shown to have diminishing effects on mosquitoes, and there are alternative measures that work, why is there such a strong push to spray? One must remember that where spraying of this nature is used by the WHO, it is used as the lesser of two evils in regions where the risk of mosquito-borne illness and subsequent death or disability is high enough to justify its use. Are there enough cases of West Nile in our area that spraying is justified? Has there been enough sampling of mosquito populations? What is the correlation between the ratio of mosquitoes with West Nile and the number of diagnosed cases? Are larvicide or other control measures being optimally used?

As a scientist who teaches the physical sciences and who does health-related research, I’m struggling to understand how the data can possibly support a decision to spray.

[1] US Environmental Protection Agency; Office of Pesticide Programs. (2011). “Pyrethrins/Pyrethroid Cumulative Risk Assessment.” Retrieved from US Environmental Protection Agency.

[2] Xu Wang et al., “Permethrin-induced oxidative stress and toxicity and metabolism. A review,” Environmental Research, Volume 149, August 2016, Pages 86-104.

The Zika virus and Chester County

by Nathaniel Smith, The Times of Chester County, 9/1/16

Getting rid of standing water is more effective than spraying

News has come around lately that “Pennsylvania Is Now One Of The Top States With Zika Virus ” (Phoenixville Patch, 8/23/16). Currently PA ranks 5th in the number of diagnosed Zika cases. Of course, no one knows how many undiagnosed cases there are anywhere.

Quick quiz: how is Zika spread? If you answered “by mosquitoes,” you’re only half right. It’s our fault too.

It’s important to focus on this note in the article: “All of the cases were travel-related, according to the Centers for Disease Control and Prevention.”

That means no human has acquired Zika from a mosquito in PA. Although the prime mosquito host for Zika, aedes aegypti, does exist in Pennsylvania, it doesn’t do well this far north (yet).

The fact is that Zika is spread not only by mosquitoes but also by people, whether through sexual contact (CDC offers explicit advice on this aspect) or from carrying the virus (usually without symptoms) and being bitten by a mosquito that in turn bites someone else, who thus acquires the disease. The aedes albopictus mosquito, often called “Asian tiger,” has become very numerous in PA but fortunately does not seem to transmit Zika very well (yet).

Spraying pesticides is a limited, short-term fix that leaves many adult mosquitoes alive and does not affect eggs and larvae but harms many forms of life and can lead to acquired immunity. Mosquitoes breed over 500 times faster than people, so they will become immune to whatever we do against them much faster than we can evolve to resist them. Mosquitoes in Puerto Rico and Florida are already becoming resistant to permethrin, the standard anti-mosquito pesticide.

This is all not good news, except that in PA we do have some time to get ready for present and future mosquito-borne diseases….

read more at The Times of Chester County

Please do not expand mosquito spraying due to Zika panic

by 18watt_fan, PolkMoms, February 8, 2016

Poison is not the answer.

Long term, it always makes the problem much worse. Not only does it contribute to selection-pressure which leads to the breeding of more virulent/robust pathogens and ‘pests’, it also kills-off natural predators to the mosquito or whichever ‘pest’ that is being poisoned.

In addition, all of this spraying is very harmful to beneficial species, such as honeybees, various fish, birds and yes, even humans.

Here’s an excerpt from a petition that’s circulating in Dallas TX concerning this issue:

“The city of Dallas sprays the poison Permethrin, a deadly poison to MANY insects. That includes beneficial insects such as honeybees and ladybugs as well as natural mosquito predators such as dragonflies. Many beekeepers around Dallas have reported their bees have been killed. In addition, fish, some of which eat mosquito larvae, are killed by this poison. There is also other wildlife to consider such as bats, birds, and geckos, which all prey on mosquitoes but are harmed by the spraying….”

Read more at PolkMomsand also watch the video “West Nile Spraying Puts Dallas Bees in Peril.”

A Q&A with Margaret Hudgings

By Nathaniel Smith, Columnist, The Times of Chester County, September 29, 2015

An interview with leader of local group questioning mosquito spraying

My opinion piece “Mosquito spraying: why doesn’t the county want to talk about it?” in the Times of Chester County, August 31, asked many questions. Since then I’ve found many answers, including from talking with the County Health Department, and many new questions too. One thing I’ve learned is how complex this subject is, since it depends on the always lively interaction of the human and the scientific.

I think West Chester has a good opportunity now, as this year’s mosquito season trails off, for cooperation between citizens, the Health Department, and the Borough government (and the same could apply in other municipalities.

For now, I have written up an interview with Margaret Hudgings, who has been leading the citizens group (of which I have been part) that is dialoguing with the Health Department and the Borough in an effort to avoid public insecticide spraying if at all possible.

How did you get interested in the issue of mosquito control?

MH: I became interested in mosquito control in 2012, when I realized that the Borough was about to be sprayed with permanone, whose active element permethrin is listed among toxic chemicals in Greenpeace’s “Black List of Pesticides.” Our son became sensitive to chemicals in his early 20’s and so we as a family have become very aware of the chemicals in our environment.

When did you become an activist in this area?

MH: I became an activist this past summer when we realized that once again the County planned to spray in the Borough. After the last dose in 2012, our son became so ill he could not return to his home near Everhart Park for months. After consulting Mayor Comitta, I decided to create a petition and go out in the Borough to talk to our neighbors about their feelings on the County’s pesticide spraying….

read more at The Times of Chester County