July 1 2013
Alarmism May Contribute to West Nile Virus Illnesses
Alarmism and junk science surrounding pesticides may translate into more sicknesses and deaths related to the mosquito-carried West Nile Virus. Activists and others are attacking products that local public officials need to reduce mosquito populations and public health risks.
In the past, activists have attacked insect repellants containing the chemical DEET. But one of the best things you can do to reduce risks for your kids and yourself is to use insect repellants, particularly those that contain the chemical DEET.
Most recently, the State of Connecticut funded a study to assess the potential impacts of larvicides on lobsters that live in the Long Island Sound. Larvicides are added to ponds and anywhere water might collect—some of which may eventually migrate into the Long Island Sound—to prevent mosquito larvae from developing into adult mosquitoes. But Connecticut legislators recently passed a law restricting use, just a few months before the state is expected to release the report findings.
I have researched this issue in the past and have blogged at Open Market, and the story never seems to change much. Lobstermen want someone to blame for lower than desired catches, so they allege that pesticides are the problem and demand government payments.
Problems began in 1999 when the Long Island Sound experienced a massive lobster die-off. Lobstermen blamed the pesticide spraying used to control the spread of the deadly mosquito-borne West Nile Virus. But the spraying occurred after the die-off began–it could not have caused it.
Researchers pointed to more likely causes: the region’s overly warm water and parasites. In fact, the Long Island Sound is marginal for American Lobster habitat, being the most southern portion of this habitat. In addition, the lobster die off followed years of unusually high lobster catch (also known as “landings”), and current catch levels are more akin to historic levels. It may be that over fishing or just a blip allowed lobstermen to do unusually well few for a few years in the 1990s (see chart). But it’s not reasonable to expect that to continue forever.
Nonetheless, lobstermen sued the pesticide company involved and netted $12.5 million in a settlement in addition to receiving $3.65 million in federal disaster payments. They proved nothing, but gained quite a bit.
This attack on larvicides comes without much justification or balancing of the risks to humans. Last year, the mosquito-borne West Nile Virus caused a record number of deaths and the second highest number cases (deaths and illnesses combined). In addition, West Nile can produce permanently debilitating neurological diseases.
While many activists downplay these risks, West Nile risks are surely multitudes higher than risks to lobsters or public health from pesticides. You can see the case counts on the Centers for Disease Prevention and Control (CDC) website. See my paper on this for more details.
The Connecticut Post has pretty good news coverage on the topic. It’s worth quoting a length:
Still, the American Mosquito Control Association, a trade group, says there is no scientific rationale for the restrictions and that both substances break down quickly and have been used safely for the last 30 to 40 years.
Methoprene is "not a toxin, per se -- it just keeps the larvae from advancing to the next stage," said Joseph Conlon, a spokesman for the AMCA. "It's very specific to mosquitoes -- if it's applied as the label instructs, it will only take care of mosquito larvae."
Theodore G. Andreadis, of the Connecticut Agricultural Experiment Station and one of the leading experts in the world on mosquitoes and the spread of West Nile virus, said the legislation was "a bit premature" and the data doesn't back up the restriction.
"I read all of the testimony," he said, "and from my perspective as a scientist, there are a lot of other factors going on, not the least of which is warming of the Sound."
Andreadis said the restriction "takes away one of the tools in our arsenal" used to combat mosquito-borne diseases.
He noted that resmethrin isn't used in water.
"The data wasn't enough to warrant this -- the dilution factor in the Sound is so great," Andreadis said.
Thomas O. Crist, a zoologist at Miami (Ohio) University and an expert on comparative invertebrate zoology, said although both mosquitoes and lobsters are arthropods -- animals with external skeletons and jointed legs -- the two have significant differences in the way their larvae develop.
"Both are aquatic larvae, but they're different in their structure and physiology," Crist said. "And the lobster larvae is floating around in a pretty large body of water, while the mosquito larvae is going to be exposed right where they're spraying, so the exposure would be quite a bit different."
Andreadis said the state Department of Energy and Environmental Protection is studying this issue, and its report is due out in the fall.
"It would have been nice to wait for that report -- once something is banned, the likelihood of bringing it back is slim," he said.