MRCU using controversial pesticide

| 13/08/2019 | 78 Comments
Cayman News Service
MRCU plane in action

(CNS) Updated: The Mosquito Research and Control Unit has confirmed it is still using a controversial pesticide as part of its arsenal of weapons against the pests. In response to enquiries by CNS, MRCU Director Jim McNelly said chlorpyrifos is used as a rotational tool where mosquitoes exhibit a resistance to pyrethroid-based products. But this chemical has been linked to genotoxic and neurological effects in children, and the European Union said recently that no safe exposure level ­can be set for the substance.

Although the chemical is still registered for use by the US Environmental Protection Agency, the Obama administration had planned to ban the its use. But under the Trump administration, that decision has been reversed. Six US states are now pursuing a lawsuit challenging the EPA for continuing to allow what is now believed to be a dangerous toxin to still be sprayed on crops.

McNelly said that over a year ago the MRCU made the decision to move away from the routine use of chlorpyrifos and was using up the last of the stock. He added that most of the unit’s efforts focus on controlling the larval stages of mosquito development, which happen in standing water.

“It is expected that this chemical will be completely depleted within a week or two,” he said, adding that any future use would be contingent on the need to respond to mosquito-borne diseases. “It is used in rotation with other insecticides to control adult, biting mosquito populations. Insecticides like this are always the last tool to be deployed from our toolbox.”

McNelly explained that, as part of its research work, the MRCU had decided to begin incorporating a new product to offset the diminished use of chlorpyrifos. The new product is Merus, an adulticide with natural pyrethrin as the active ingredient.

“This product is Organic Materials Review Institute (OMRI) Listed, meaning it is approved for wide area use in urban or residential areas, as well as in and around organic farms and gardens,” McNelly said. “It is made with imported natural pyrethrins, a botanical insecticide that is naturally occurring in chrysanthemum flowers. The Merus formulation includes no petroleum distillates or chemical synergists, and is highly effective on a wide range of mosquito species.”

However, a representative from OMRI has informed CNS that McNelly’s description of the OMRI list is not accurate. “OMRI listing means that a product has been determined to be compliant to organic standards. OMRI does not test for safety, nor do we advocate that any OMRI Listed pesticide be widely used in urban or residential areas,” the representative stated.

She added, “A search of OMRI Listed Merus products brings up four results; two products for use on livestock (which would not be appropriate in this instance) and two for use on crops, with restrictions. It’s unclear which product this article is referring to… It should also be noted that OMRI does not review products for use in the Cayman Islands. We currently review to US and/or Canada organic standards.”

McNelly said the formulations used by the unit to control mosquitoes embrace the principles of integrated mosquito management, which includes balancing the goals of public health and public preference.

“As our name implies, an important aspect of our mission is research, and we are always looking at new active ingredients, and new approaches that reflect best practice in using these active ingredients to control mosquitoes and mitigate mosquito-borne disease,” he stated.

Meanwhile, following multiple inquiries from readers about the chemicals currently being used by the MRCU and how they are deployed, McNelly confirmed the list of products it has used over the last month are as follows:

  • Mosq Mist II by plane and truck
  • Fyfanon by plane
  • Vectobac WDG by plane
  • Vectobac GS by plane
  • VectoPrime by plane
  • Natular G30 by plane and hand applications
  • Natular G by plane

This article was updated on 15th August to include the statement by OMRI.

For more information about the adulticides, larvacides and pesticides used by the MRCU, see the listings here and here.

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Category: Health, health and safety

Comments (78)

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  1. Chet Oswald Ebanks says:

    Oh my, What else is new. I wasn’t yet born when our islands was being sprayed with even more dangerous chemicals. Those where the days am told that the dyke roads where dug and constructed. And everyone wonders why this country cancer rate is rising. It was did to control the mosquitoes and bring tourism to our shoes. Tourism, it ain’t helping the average Caymanian who can’t afford to live in their own country anymore. And not let us forget those lovely pillet food they feed the turtles at turtle farm. Another reason Cayman cancer rates are over the top.
    But those who continue to vote the same person’s into our LA are to blame. Think about it this day. Are Caymanians any better off 50 years later. No.

  2. Anonymous says:

    If these MLA’s cared and put as much effort into these issues as they do about denying gays equal rights then this place would truly be a paradise. Sadly some minds are not expanding.

    • Anonymous says:

      I will .say it for you all who are skirting around this issue . I call for the immediate firing of the person(s) responsible for this atrocity. Now not tomorrow and every one of you commenting on here should get off your ass3s and protest at the doorsteps of the Government Admin building.

  3. Anonymous says:

    No one on this island has the balls to do anything to make changes. How many people have you seen picketing or protesting here? Exactly. Don’t even mention MLA’s…what have they done for environmental change and sustaining the life of the island and the humans on it? anything at all?

    • Anonymous says:

      They like their toxic cocktails. They prefer run, walk, swim or whatever for cancer. They prefer awareness campaigns for birth defects and congenital abnormalities. Awareness campaigns and funds raising gala events are very trendy. Gives one opportunity to wear that expensive cocktail dress. It would have been funny if it wasn’t tragic. Human minds work backwards.

    • Anonymous says:

      Too many are quick to open their mouth but then do nothing about it!!!

      • Anonymous says:

        What puzzles me, there are many well-off people living in Grand Cayman permanently. Tons of attorneys. Why do they remain quiet?

    • Anonymous says:

      They were protesting against Oxitec, Idiots.

  4. Anonymous says:

    I wonder if CNN reads this site, there’s a lot of things on here tourists should know about.

  5. Anonymous says:

    You need your own Erin Brokovich to build a case against GIG for knowing or negligent environmental violations. In the US Negligence-Based Environmental Crimes cases can be criminal.

    P.S. Erin Brockovich is an American legal clerk, consumer advocate, and environmental activist, who, despite her lack of formal education in the law, was instrumental in building a case against the Pacific Gas and Electric Company of California in 1993.

  6. Anonymous says:

    Vectobac WDG + GS + Vectoprime

    For terrestrial Uses: Do not contaminate water when cleaning equipment or disposing of equipment washwaters. Do not apply directly to treated finished drinking water reservoirs or drinking water receptacles when water is intended for human consumption.

    Natular G + G30

    Environmental Precautions:

    Prevent product from entering into drains and waterways. Collect and dispose of this
    material and its container in accordance with national and regional regulations. If the product has contaminated surface water, inform the appropriate authorities.

  7. Anonymous says:

    Already scared just googling the first one!!!

    The active ingredient in Fyfanon ULV Mosquito is malathion.

    Malathion is of low toxicity; however, absorption or ingestion into the human body readily results in its metabolism to malaoxon, which is substantially more toxic.[17] In studies of the effects of long-term exposure to oral ingestion of malaoxon in rats, malaoxon has been shown to be 61 times more toxic than malathion,[17] and malaoxon is 1,000 times more potent than malathion in terms of its acetylcholinesterase inhibition.[18]Indoor spillage of malathion can thus be more poisonous than expected, as malathion breaks down in a confined space into the more toxic malaoxon. It is cleared from the body quickly, in three to five days.

    In jurisdictions which spray malathion for pest control, it is often recommended to keep windows closed and air conditioners turned off while spraying is taking place, in an attempt to minimize entry of malathion into the closed environment of residential homes.

    Malathion is classified by the IARC as probable carcinogen (group 2A). Malathion is classified by US EPA as having “suggestive evidence of carcinogenicity”.

  8. Anonymous says:

    Does any notice how many people have a cough they can’t shake, it keeps hanging on. God help us

  9. satirony says:

    The mosquito plane was spraying over the mangroves by Patrick’s island last night. Of course I don’t know if was dispensing Chlorpyrifos, which is highly toxic to aquatic life and very toxic to birds. This concerns me a lot, as hundreds of white-crowned Pigeons and Antillean Grackles fly in to roost in these mangroves in the evenings at the same time as the mosquito plane operates. The plane appeared to avoid the large Heron roost in the lake nearby, and I hope it always does.

    Our bees are very active when the mangroves are in flower, and they forage in their hundreds of thousands. One imagines the scientists at MRCU are extremely sensitive to the possibility of collateral damage, but now I wonder just how careful they really are, seeing how controversial Chlorpyrifos is, a chemical designed in the 1960s. As with antibiotics, pests become immune to pesticides and so it’s always tempting to resort to more toxic ones, but in this case the use of Chlorpyrifos appears shocking.

  10. Anonymous says:

    It actually causes harm to the nervous system, and affects brain function especially in developing children.

    It is also lethal to the local bee population.

    • Anonymous says:

      There goes my hopes of us having a bee farm again…

      • Anonymous says:

        I hear you and saddened as well.
        I only buy honey directly from New Zealand. Collected in NZ, shipped from NZ. The shipping cost is quite reasonable (to the U.S.). All U.S. honey is contaminated with pesticides. You can’t track every bee.

  11. Anonymous says:

    Hope everyone that had something bad to say about Oxitecs plan to eradicate one of the dangerous mosquitos reads or hears about this.

  12. Serial killers says:

    And we wonder why the cancer rate is so high in Cayman. Daily showers of these poisons from planes and drive by trucks.

  13. Anonymous says:

    Could it get more depressing on these islands of “paradise”?

    • Anonymous says:

      The Caymans are becoming a toxic wasteland and it’s just getting worse. I can’t believe wealthy people would want to live in place that has little regulations and polluted water and air. The fact that there are no reports on air or water quality really makes you wonder what’s going on down there.

      • Anonymous says:

        I was browsing CNS site yesterday and out of curiosity clicked on SeaFire properties for sale since it was getting in my face. Was surprised how institutional $7mil. units look and how many are not sold.
        So, I guess, wealthy people are not stupid to invest in a toxic wasteland.

  14. Anonymous says:

    Welcome to Grand Cayman! Did you bring your own hazmat suit?

  15. mekk says:


  16. Anonymous says:

    So spray the swamps with it but not residential areas.

  17. Anonymous says:

    This is why the green iguana is so dangerous to eat, the poison builds ups up in their system as they eat more and more mosquitos.

    • Anonymous says:

      Incorrect. Green iguanas are primarily herbivorous and eat plant matter (leaves, flowers, fruit etc). They dont eat mosquito’s. Eat them to beat them! The animals you should be concerned about are the bats who are insectivores and rely heavily on mosquitoes as a source of food…

    • Anonymous says:

      Yeh, gotta be careful of them greenies flying around gobbling up mosquitos, wait…. What???

    • Anonymous says:

      They’re herbivores….

  18. Anonymous says:

    These are some of the life-and-death, quality-of-life public heath concerns that our MLAs and Ministers should be holding legislative public hearings on and not for political grand standing but meaningful debates with experts to ensure public safety instead of some of the nonsense I see coming from, among other things, private members motion.

    Truth be told, what is needed is more than a name change in name from the Legislative Assembly to Parliament that is intended to fill the huge egos of politicians but fundamental changes to have meaningful committee hearings and findings that will educate and improve our quality of life.

    And another thing, regarding constitutional changes, we now know (as I always believe) that single-member constituencies are a waste of taxpayer dollars and only serve to divide small communities into smaller parochial territories (hopefully not eventually into garrison strongholds) for politicians, some of whom would have ever been elected had it not been for this system that was designed to control a certain politician but is now having the reverse consequences.

    Returning to the subject in the first instance, I don’t have the scientific evidence and it might be held from us the public but I believe that this decades-old chemical rainfall on us the citizens have or contributed to the high numbers of cancer in this society, especially at a time not so long ago when water was collected in cisterns from rooftops bathed in chemical.

    We deserve nothing more than the truth and transparency from our elected officials.

    • Anonymous says:

      Those who are dead from or currently fighting cancer ARE the evidence. How much more evidence one needs?
      Science is certainly not my God. As someone who suffers from a different kind of health issue, which science denies, I find support on

    • Anonymous says:

      LOL. Don’t rely on MLA’s for anything.They don’t want to hurt their uncles nephews daughetes feelings. Only the people can make a difference. GET UP STAND UP

    • Anonymous says:

      When on earth have we EVER gotten “truth and transparency from our elected officials”?

    • Anonymous says:

      Some of us still collect roof water to cisterns for potable use and have been told by MRCU, (up to a few months ago) in writing, that our water is safe to drink!!

  19. Anonymous says:

    This is what visitors say:

    Murtle says:
    20/06/2018 at 3:18 pm
    I am very concerned about this information as I am currently in the caymans visiting!! Tonight we were walking back from dinner at the westing and suddenly saw a truck with a siren. We weren’t sure what it was and suddenly this truck sprayed this something literally within approximately 10-15 yards of us. My husband suddenly said mosquito spays… we all turned away and covered our faces. I was SO UPSET!!! I couldn’t believe they sprayed this with us right there. I am horrified as to what side effects—if any— we might have from this!!!???. Murtle

  20. Cheese Face says:

    Stop using this s*** now you complete morons, you are poisoning your own families (and mine). Just get rid of the s***. If the gov can afford to send big mac to Jamrock for a big party, they can afford to ditch this crap and stop killing us.

    Total disbelief that his is allowed to continue.

  21. Anonymous says:

    Are you going to perform public announcements so we can keep our children inside during the spraying? It’s the least you can do since you’ve made the decision to keep playing roulette with our lives

  22. Elvis says:

    Another dose of cancer anyone?
    And they wonder why so much cancer on the island? Get a grip folk ffs

  23. Anonymous says:

    Not really news. Move on.

  24. Anonymous says:

    I don’t believe this! McNelly knows this chemical is very harmful but he wanted to use up the stock!! Wasn’t there safe way to dispose of it instead of poisoning us with it . Is he serious? He really need to be relieved of his job- is he the best we can get? Government needs to spend some of the huge surplus to sort up the dump and come up with some safer way of keeping the mosquitoes under control!!

    • naturegirl says:

      Let the mosquitoes be. Our bats and on-the-wing insect feeding birds need them and can eat huge quantities. Watch the nightjars. Notice how few swallows we have passing through here twice a year now on their migration? No fuel for them. When did you last see a firefly? Dead bees all over the tennis courts after mosquito spraying. There are still many, many people who rely on cistern water which for those who don’t know, is rain water caught off the roof. Stop spraying carcinogens!!

  25. Anonymous says:

    Keep spraying west bay… it’s only a matter of time.

  26. chemical free says:


    nough said

  27. Anonymous says:

    While this pesticide may, in scientific eyes, help to reduce mosquito populations, it doesn’t change anything towards the excessive swampy lands around the island and the residents who back rain water in buckets around their homes.
    Let’s also not forget the outrageous smell of this toxin via truck when it is driving around residential areas at night.

  28. Anonymous says:

    The damn dump will kill us all long before MRCU does. Fix it, morons!

    • Anonymous says:

      Fix the damn dump right where it is.

      The District where the majority of waste is generated.

      Unna so smart and have plenty money so just find the scientists that can solve it.

    • Erin Brokovich says:

      Sorry, it is unfixable. TOO LATE and it keeps growing. They could make it look pretty though. But it will continue its poisoning.
      Your leaders and MLAs think they are invincible. Just wait and see. There is no cure for cancer, by the way, just extension of suffering. Walter White has clearly demonstrated that in Breaking Bad. No money in the world would help you.


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