Aedes aegypti mosquito carries Dengue.
With cases of Dengue fever reportedly continuing to climb across the territory, Department of Health officials recently announced a plan to release a chemical fog this month to target the mosquito population.
Several St. John residents, however, aren’t convinced the chemical fog will make much of a difference, and they want to know more about possible effects.
“We need to re-think the whole idea,” said St. John environmental scientist Gary Ray. “It’s the sort of thing that was deemed acceptable 50 years ago, but long since discontinued everywhere in the modern world in which science informs public policy.”
DOH is using a chemical called Permanone 30-30, which the department has used in years past. The focus of the fogging, scheduled for Thursday, January 17, from 6 to 9 p.m. in Cruz Bay and Coral Bay, is to kill off “nuisance mosquitoes,” which are not necessarily the species which transmit Dengue fever, explained Senator at Large Craig Barshinger, whose office has received complaints about DOH’s fogging plans.
“The Aedes aegypti mosquito which carries Dengue fever generally likes to hide inside the house,” said Barshinger. “So if you are going after ‘nuisance mosquitoes’ I’m not sure how effective that is going to be in reducing the risk. There are two things; it’s poisonous and it’s non-targeted so it could kill a lot of beneficial species without making a big impact.”
Fogging will impact the public and millions of native and beneficial insects, according to Ray.
“On St. John there are two main risks areas: acute exposure of the public and the machinery operators; and natural communities,” said Ray. “St. John is mostly Park, and spraying will kill millions of native, beneficial insects that pollinate plants, control herbivory of natural communities, and so forth.”
DOH does not plan to monitor residue after fogging, Ray added.
“Residues will likely not be monitored,” he said. “‘Spray and Run’ is more likely. Nature and humans in their homes are targets, not merely Aedes aegyptii mosquitoes.”
Dengue fever is caused by a virus transmitted by Aedes aegypti mosquitoes, which are most often found in and around the home and are active during the daytime. In order to reduce the number of mosquitoes, residents are urged to empty any containers which could collect water like plant pots, empty drums and food bowls for pets.
In a prepared statement, DOH officials explained that the fogging would be conducted in addition to other mosquito elimination efforts.
“The fogging will be conducted in addition to other mosquito abatement efforts like Larviciding, which involves the treatment of water sources that hold mosquito eggs, or Larvae, to kill off the immature mosquito before it becomes a flying mosquito,” according to the DOH. “This method of mosquito abatement was chosen because it is deemed more environmentally friendly and more effective in controlling Aedes mosquitoes.”
The DOH statement, however, also noted that fogging by itself does not reduce the risk of Dengue fever.
“Fogging helps to kill off the increase in mosquito population that normally comes with heavy rains but residents are reminded that fogging by itself does not effectively reduce the risk of Dengue transmission,” according to the DOH statement.
If the fogging doesn’t make a difference in the battle against Dengue fever, then why fog at all, asked Barshinger.
“People need to be able to weigh the risks versus the benefits of fogging,” said Barshinger. “If it’s only to get rid of nuisance mosquitoes, then it should be discontinued immediately, because who cares about that. If you could take a small risk and eliminate the danger of Dengue fever, that would be a pretty good trade off, but that doesn’t seem to be the case here.”
“There needs to be some natural expectations because you don’t just shoot blind folded,” said the senator at large. “If you want to fog you have to have a clear health benefit and cost benefit.”
With so little scientific information about the risks and rewards of fogging with Permanone 30-30, DOH’s program seems like a “feel good” response, explained Barshinger.
“With so little information, this program almost smacks of a feel good response,” he said. “The government says, ‘See, we did something; we paid money to get rid of those nuisance mosquitoes.’ But the problem is that we don’t know more about this.”
What is known about Permanone 30-30 is that it is “extremely toxic” to fish and aquatic invertebrates, according to the chemical’s warning label produced by Bayer Environmental Science.
“This pesticide is extremely toxic to fish and aquatic invertebrates. Runoff from treated areas or deposition of spray droplets into a body of water may be hazardous to fish and aquatic invertebrates. Do not apply over bodies of water (lakes, rivers, permanent streams, natural ponds, commercial fish ponds, swamps, marshes or estuaries), except when necessary to target areas where adult mosquitoes are present, and weather conditions will facilitate movement of applied material away from the water in order to minimize incidental deposition into the water body.”
The label also details that the chemical is highly toxic to bees exposed to direct treatment on blooming crops or weeds.
Even the DOH prepared statement cautioned “those with compromised immune systems to stay indoors and close windows at the time that fogging is being conducted.”
What residents want is more information, explained Ray.
“Will we reduce cases of Dengue by fogging,” said Ray. “Perhaps; perhaps not. It’s rather ill-advised to risk injury to hundreds or thousands of Virgin Islanders who breathe the aerial spray for an uncertain outcome on the Dengue end.”
“The technology is primitive and the price paid is steeper than any positive effect,” Ray said.
DOH officials fogged St. Croix last week and were scheduled to fog St. Thomas on January 15 and 16 and St. John on January 17.
Residents with questions about the DOH’s fogging plan should call the department at 774-0117.
