Subject: WEST NILE VIRUS--------The need for honest discussions not more silence--- To: Paul Helliker <phelliker@cdpr.ca.gov> Dear Mr. Helliker,
I thought you might like to read RACHEL'S ENVIRONMENT & HEALTH
BIWEEKLY #709 & #710 on the
WEST NILE VIRUS. Part 1 by Rachel Massey* West Nile virus (WNV), a disease previously unknown in the
Western Hemisphere, appeared in New York City last year and has now spread to
animal populations in six other states. Some municipal officials have responded
to the disease by spraying entire neighborhoods with pesticides intended to kill
mosquitoes. West Nile Virus can cause serious illness and death in some cases,
but spraying pesticides to kill mosquitoes is not a good solution. Spraying
exposes large numbers of people to toxins with both short- and long-term health
effects, and studies suggest it is unlikely to be effective. Transmitted by mosquitoes, WNV primarily attacks birds but
can also infect humans and other animals. Most infections with WNV go unnoticed
or feel like an ordinary flu, but some cases lead to encephalitis (inflammation
of the brain) or meningitis (inflammation of the membranes surrounding the brain
and spinal cord) and can be fatal. The elderly and individuals with compromised
immune systems may be particularly vulnerable to serious illness resulting from
the virus. In 2000, WNV has reappeared in New York City, and infected
birds have been found in upstate New York as well as New Jersey, Massachusetts,
Rhode Island, New Hampshire, Connecticut, and Maryland.[1] In the 1999 outbreak,
sixty-two people became seriously ill and seven died. The individuals who died
of the virus ranged from 68 to 87 years of age.[2] Of the fifty-five individuals
in New York City who survived severe cases of the virus, some continue to suffer
neurological problems a year later.[3] As of October 7, a total of 17 human cases of WNV had been
detected this year, 3 in New Jersey and 14 in New York.[4] One individual, an
82-year-old man in New Jersey, has died of the virus this year.[5] Recent
outbreaks have occurred in other countries as well; in Israel, over 120 people
have shown symptoms of WNV infection this year and 10 have died.[6] In a study conducted last summer, researchers tested blood
from 677 randomly selected individuals in a 4-square-mile area around the focal
point of the outbreak in Queens, N.Y. Of these 677, 19 showed evidence of having
been infected with West Nile virus. Based on these results, the researchers
estimated that 2.6% of the individuals in the area studied were infected with
the virus. About a fifth of these exposed individuals had experienced symptoms
attributable to the virus. This study supports the view that most individuals
infected with the virus never develop noticeable symptoms.[7] The Centers for
Disease Control (CDC) estimates that the case-mortality rate for WNV(the
proportion of individuals showing symptoms who die of the disease) is three to
fifteen percent, with the fifteen percent figure applying to the elderly.[8] Mosquitoes begin life as eggs laid in stagnant water; later
they change into water-dwelling larvae, then pupae, and finally adults. Thus
they can be controlled by several means -- by minimizing standing water, by
maintaining populations of egg- or larva-eating fish, or by applying chemicals
that kill either larvae or adults. New York City responded to the appearance of the virus last
year by spraying the organophosphate insecticide malathion from trucks and
helicopters to kill adult mosquitoes. Organophosphates act as nerve toxins,
disrupting the nervous system by inhibiting the enzyme cholinesterase.
Short-term symptoms resulting from human exposure to organophosphates can
include breathing problems, headache, nausea and dizziness. High exposures can
produce fatal poisoning.[9] In April 2000, a U.S. Environmental Protection
Agency (EPA) committee reviewed a series of studies on mice and rats exposed to
malathion. Based on this review, the committee concluded that there was
"suggestive evidence of carcinogenicity" which was "not
sufficient to assess human carcinogenic potential."[10] For the moment
malathion remains listed by EPA as "not classifiable" with regard to
carcinogenicity. Malathion is also a suspected hormone disrupter.[11] This year, New York and other municipalities have used
pyrethroid insecticides such as Scourge (active ingredient, resmethrin) and
Anvil (active ingredient, sumithrin) to kill adult mosquitoes. The pyrethroids
also act as nerve toxins, and may have other long-term health effects.
Resmethrin has been found to act as a weak hormone mimic in test tube
studies.[12] A 1999 study on how pyrethroids affected breast cancer cells in a
laboratory setting led researchers to suggest that the pyrethroids as a group
should be considered hormone disrupters.[13] EPA is scheduled to re-evaluate the
health effects of the pyrethroids in 2002. Pyrethroids are also very toxic to fish and to bees, and
there are regulations against applying them on or near bodies of water.[14] It
is particularly important to pay attention to their effects on fish when
designing a mosquito control program, since healthy fish populations can serve
as an important natural mosquito control. Like several other pyrethroid insecticides, Scourge and
Anvil contain piperonyl butoxide (PBO), which is added to enhance the toxicity
of the active ingredients. Studies have linked PBO exposure to liver cancers in
rats and mice,[15] and it is classified by the EPA as a possible human
carcinogen. There is also some evidence that PBO-pyrethroid mixes can affect the
human immune system.[16] Intentionally spraying thousands of people with suspected
carcinogens or hormone disrupters seems dubious from a public health
perspective. Potential effects on fetuses, infants, and children are of
particular concern. Increasing evidence supports the view that even tiny
exposures to toxic chemicals can have devastating effects on infants and
developing fetuses, depending when the exposures occur.[17] There has been considerable variation in responses to WNV
this year. When infected birds began appearing in the Boston area, several
municipalities began aggressive spraying to kill adult mosquitoes in an area
defined by a two-mile radius around the site where an infected bird was found.
Buffalo, N.Y., on the other hand, has limited itself to the use of larvicides
placed in standing water without spraying.[18] Some municipalities have used chemical larvicides such as
Altosid (active ingredient, methoprene), to kill mosquito larvae in catch basins
and other standing water. When exposed to sunlight, methoprene breaks down into
a class of chemicals closely related to vitamin A, known as retinoids, which can
cause birth defects in humans and may be contributing to the global epidemic of
skeletal deformities in frogs (see REHW #590 and #623 ). Other municipalities
have opted for least-toxic control measures, including the use of BACILLUS
THURINGIENSIS ISRAELENSIS (BTI) and BACILLUS SPHAERICUS , naturally-occurring
bacteria that are toxic to mosquito larvae. Long-term health effects of spraying pesticides in urban
areas are probably the greatest concern, but acute exposures can also be a
problem. Municipal officials in charge of spray programs in New York and other
cities warned residents to remain indoors during the scheduled spray times,
closing windows and turning off air conditioners to prevent the chemicals from
entering their homes. But in one case, a New York resident was sprayed at close
range when trucks began spraying at 10:00 pm rather than at midnight, as they
had been scheduled to do.[19] At an April, 2000 meeting in New York, several
people said they thought they were suffering neurological problems resulting
from the spraying, and one doctor said she had seen 160 patients with minor
neurological problems possibly attributable to the spraying.[20] ============================ * Rachel Massey is a consultant to Environmental Research
Foundation. [1] "Update: West Nile Virus Activity --- Northeastern
United States, 2000," MORBIDITY AND MORTALITY WEEKLY REPORTS 49: 36,
September 15, 2000, pgs. 820-2. And: "West Nile virus continues to spread
south in US," Reuters Health Information, September 22, 2000. See
www.reutershealth.com. [2] New York City Department of Health, "West Nile
Virus: A Briefing," CITY HEALTH INFORMATION Vol. 19, No. 1, May 2000, pg. 2
[3] David W. Chen, "Lives that have been changed
forever from the aftereffects of a mosquito bite," NEW YORK TIMES August
19, 2000, pg. B1 [4] United States Department of Agriculture Animal and
Plant Health Inspection Service (APHIS), "Update on Current Status of West
Nile Virus, Week of 1 October through 7 October, 2000." Available at
http:www.aphis.usda.gov/oa/wnv/wnvstats.html. [5] Grant McCool, "N.Y. reports its 14th case of West
Nile virus," Reuters Health Information, October 5, 2000. See
www.reutershealth.com. [6] "West Nile virus continues to spread south in
US," Reuters Health Information September 22, 2000. See
www.reutershealth.com. [7] New York City Department of Health, "West Nile
Virus: A Briefing," CITY HEALTH INFORMATION Vol. 19, No. 1, May 2000, pg.
2. [8] Centers for Disease Control, "West Nile Virus:
Questions and Answers." Available at http:www.cdc.gov/ncidod/dvbid/westnile/q&a.htm
. [9] J. Routt Reigart and James R. Roberts, RECOGNITION AND
MANAGEMENT OF PESTICIDE POISONINGS. (Washington, D.C.: U.S. Environmental
Protection Agency Office of Pesticide Programs, 1999). Available at
http:www.epa.gov/oppfead1/safety/healthcare/handbook/handbook.htm . For a
thorough overview of malathion's health effects see Loretta Brenner,
"Malathion," JOURNAL OF PESTICIDE REFORM Vol. 12, No. 4, Winter 1992,
pgs.29-37. [10] Cancer Assessment Review Committee, Health Effects
Division, Office of Pesticide Programs, "Cancer Assessment Document #2:
Report of the 12-April-2000 Meeting: Evaluation of the Carcinogenic Potential of
Malathion." Available at http:- www.epa.gov/pesticides/op/malathion.htm
(omit the hyphen). [11] Stephen Orme and Susan Kegley, PAN Pesticide Database.
San Francisco: Pesticide Action Network, 2000. [12] Ted Schettler and others, GENERATIONS AT RISK:
REPRODUCTIVE HEALTH AND THE ENVIRONMENT. (Cambridge, Mass.: MIT Press, 1999),
pg. 186. [13] Vera Go and others, "Estrogenic Potential of
Certain Pyrethroid Compounds in the MCF-7 Human Breast Carcinoma Cell
Line," ENVIRONMENTAL HEALTH PERSPECTIVES Vol. 107, No. 3, March 1999, pgs.
173-177. [14] U.S. Environmental Protection Agency, "For Your
Information: Synthetic Pyrethroids for Mosquito Control," (Washington,
D.C.: U.S. Environmental Protection Agency, May 2000). Publication
#735-F-00-004. [15] O. Takahashi and others, "Chronic Toxicity
Studies of Piperonyl Butoxide in F344 Rats: Induction of Hepatocellular
Carcinoma," FUNDAMENTAL AND APPLIED TOXICOLOGY Vol. 22, No. 2, February
1994, pgs. 293-303. And: O.Takahashi and others, "Piperonyl butoxide
induces hepatocellular carcinoma in maleCD-1 mice." ARCHIVES OF TOXICOLOGY
Vol. 68, No. 7, July 1994,pgs. 467-9. [16] F. Diel and others, "Pyrethroids and piperonyl
butoxideaffect human T-lymphocytes in vitro." TOXICOLOGY LETTERS , Vol.
107, Nos. 1-3, June 1999, pgs. 65-74. [17] See Schettler, cited above in note 12, pgs. 12-16, or
John Wargo, OUR CHILDREN'S TOXIC LEGACY (New Haven: Yale University Press,
1998), pgs. 173-8. [18] Megan Scott and Beth Daley, "Spraying for West
Nile Begins," BOSTON GLOBE July 28, 2000, pg. A1. And: Raja Mishra,
"Researchers Mark West Nile Hot Spots," BOSTON GLOBE August 11, 2000,
pg. B2. And: Kevin Collinson and Henry L. Davis, "More Funds Allocated to
Fight West Nile Virus," BUFFALO NEWS September 1, 2000, [Local, pg. 1C]. [19] Elisabeth Bumiller, "Mayor Says Pesticide
Spraying Victim Was Right," NEW YORK TIMES September 12, 2000, pg. B5. [20] "Officials Defend Spraying to Curb West Nile
Virus," NEW YORK TIMES April 1, 2000, pg. B3. WEST NILE VIRUS--PART 2 - by Rachel Massey* As we saw two weeks ago (REHW #709), West Nile virus (WNV)
appeared in the U.S. for the first time in 1999.** WNV was previously unknown in the Western Hemisphere, but it
has now spread to seven states, most recently North Carolina.[1] Carried by
mosquitoes that can infect humans, this virus often produces no symptoms at all
but can sometimes lead to serious illness. In some cities, public health
authorities have responded by spraying entire neighborhoods with pesticides
intended to kill mosquitoes. These mass pesticide sprayings pose threats to
human health and do not necessarily reduce populations of disease-bearing
mosquitoes. Experiences with another mosquito-borne virus, eastern
equine encephalitis (EEE), indicate that pesticide sprays do not necessarily
achieve the desired effect. For example, a 1997 study looked at trends in
populations of CULISETA MELANURA, the mosquito primarily responsible for
transmitting EEE among birds. Over a period of eleven years, Cicero Swamp in
central New York state was sprayed fifteen times with one insecticide and once
with another. Instead of declining, the population of CS. MELANURA grew
fifteen-fold during this period. The study suggests that the pesticides may have
altered the ecological balance of the swamp, killing organisms whose presence
would ordinarily help limit the CS. MELANURA population.[2] In general, spraying
can kill fish and other natural mosquito predators, and repeated spraying can
produce pesticide-resistant mosquitoes.[3] Pesticides meant to kill flying insects are often applied
as an ultra-low volume (ULV) spray. ULV spray equipment creates tiny pesticide
droplets that can remain aloft for long periods and, due to their light weight,
readily drift away from the target area. Scientists have estimated that less
than 0.0001% of ULV pesticide sprays actually reach the target
insects.[4,pgs.18,22] So for every droplet that reaches a mosquito, hundreds of
thousands more droplets circulate pointlessly in the environment. Effective mosquito control uses knowledge of mosquito
ecology to minimize opportunities for human exposure. One important tactic is
reducing mosquito breeding habitats. CULEX PIPIENS, also known as the northern
house mosquito, has been the principal though not the only mosquito species
transmitting WNV in the U.S. in 1999 and 2000. CX. PIPIENS breeds readily in
standing water found in places like wading pools, birdbaths, puddles, ditches,
and standing surface water from septic systems.[5] I ts typical flight range is
a quarter to a half mile.[6] This means that a mosquito that bites you on your
front porch may well have hatched in your back yard -- and that you and your
neighbors can have a direct effect on local mosquito populations. On a community level, guidelines for effective mosquito
control include: ** Do not use "adulticides," or pesticides meant
to kill adult mosquitoes. ** Focus on controlling mosquitoes in their immature forms:
eggs, larvae, or pupae. Stock ponds and other bodies of water with
mosquito-eating fish, and keep waterways clean so that fish and other mosquito
predators can survive. In some cases, it is appropriate to use bacterial larvicides or mechanical controls
such as vegetable-based oils that smother mosquito eggs floating on the surface
of the water.[3] Mechanical control of adults may be an option as well. Traps
exist that may attract and kill mosquitoes over areas of up to an acre. (See,
for example, www.mosquitomagnet.com.)[3] ** On a municipal or county level, set up a system for
citizens to report standing water near their homes.[7] ** Establish monitoring programs to pinpoint where
mosquito-borne diseases are occurring. Monitoring can rely both on trapping
mosquitoes and on "sentinel birds," such as chickens, tested regularly
for signs of infection.[3] ** Continuously evaluate the effectiveness of all mosquito
control measures. ** Make sure the public knows what people can do at home to
minimize mosquito exposure and eliminate breeding sites. Public health education
is a good investment of resources and will pay off better than quick-fix
expenditures on chemical sprays. ^Here are some steps individuals can take
around their homes:[8] ** Get rid of any unnecessary items on your property that
can hold stagnant water, such as old tires. ** Empty water from buckets, toys, and containers, and
store them in places where they will not collect rain. ** Drill holes in the bottoms of recycling bins and any
other containers that must be kept outdoors. ** Drain the water from bird baths, fountains, wading
pools, plant pots and drip trays twice a week. ** Check for other ways water may be collecting around your
house, such as puddles beneath air conditioners. ** Clean out your gutters and fix gutters that sag or do
not drain completely. Check for areas of standing water on flat roofs. ** If you have a swimming pool, outdoor sauna, or hot tub,
make sure rainwater does not collect on the cover. ** Clear vegetation and trash from any drains, culverts,
ponds or streams on your property so that water drains properly. ** Keep grass cut short and trim shrubs to minimize hiding
places for adult mosquitoes. ** Eliminate standing water in your basement. ** To minimize the likelihood of being bitten inside your
house, make sure window and door screens fit properly and replace outdoor lights
with yellow "bug lights." ** To avoid being bitten outdoors, wear hats, long sleeves
and long pants in the evenings, when mosquitoes are most active. Insect repellents can help, but some of them are dangerous.
Products containing the pesticide DEET should be avoided. The U.S. Environmental
Protection Agency (EPA) acknowledges fourteen cases in which individuals
reported seizures associated with exposure to DEET. Twelve were children, three
of whom died.[9, pgs. 22-23] DEET can also interact with other chemicals to
produce severe toxic effects on the nervous system, and may have played a role
in Gulf War Syndrome (see REHW #498 ). Based on existing information about
DEET's health effects, EPA determined in September 1998 that the labels on some
DEET-containing products were misleading. Under EPA's new requirements, it is
illegal to label DEET-containing products as designed for children or "safe
for kids." However, EPA chose to allow a grace period of more than four
years during which products with old labels can be sold [9, pg. 41], so stores
can still sell products with misleadin g safety claims. Many essential oils derived from plants have insect
repellent properties, and some plant-based formulations provide protection from
bites.[10] CONSUMER REPORTS magazine says a product called Bite Blocker is
effective for 1 to 4 hours.[11] With all insect repellents, it is worth
minimizing your exposure. Treat clothing, rather than skin, whenever possible,
and wash off repellents with soap and water after returning indoors. ^If WNV has
not yet appeared where you live, you may want to get ready in case it appears
next year. You can start now to educate your town, city,or county officials
about pesticide hazards and encourage them to develop a comprehensive
non-chemical mosquito control program. It makes sense to contact these officials
during the winter, when they are not under pressure to act quickly. ^Find out whether your city or town already has a mosquito
control program, and try to identify an individual in your public health
department who is responsible for mosquito-borne diseases. Ask whether the
department has a written plan for responding if infected birds or mosquitoes are
found in your area. ^This could also be a good opportunity to find out about and
work to eliminate "nuisance" mosquito control programs, in which
routine spraying is carried out with no public health rationale. ^Finally, you may wish to raise awareness about the links
between global warming and emerging infectious diseases. Because global warming
creates opportunities for tropical diseases to spread or move northward, the
appearance of WNV in the U.S. may be a harbinger of things to come. If your
municipality has a program to reduce emissions of "greenhouse gases"
such as carbon dioxide, talking about links to WNV could help jumpstart the
program or give it new publicity. ^Paul Epstein of Harvard Medical School's Center for Health
and the Global Environment argues that the spread of mosquito-borne diseases
like WNV is aided by several phenomena associated with global warming, including
mild winters, hot summers, and drought. The "globalized" economy and
increasing international travel also create new opportunities for exchange of
diseases across regions. According
to Epstein, back-to-back weather extremes in 1998 and 1999 probably encouraged
the proliferation of WNV and the mosquitoes that carry it. In a recent article
in SCIENTIFIC AMERICAN he writes, "The mild winter of 1998-99 enabled many
of the mosquitoes to survive into the spring, which arrived early.
Drought in spring and summer concentrated nourishing organic matter in
their breeding areas and simultaneously killed off mosquito predators, such as
lacewings and ladybugs, that would otherwise have helped limit mosquito
populations. Drought would also have led birds to congregate more, as they
shared fewer and smaller watering holes, many of which were frequented,
naturally, by mosquitoes."[12, pg. 54] Later in the summer, heavy rain
created new mosquito breeding opportunities. Higher temperatures also tend to
increase mosquito activity and accelerate the reproduction and maturation of
viruses within their bodies.[12, p.52] ^As communities make decisions about WNV, public officials
must be prepared to talk frankly about the uncertainties they face.
For example, it is not acceptable to provide ample information on risks
associated with WNV while witholding parallel information on the toxicity of
pesticides used to combat mosquitoes. As always, our ability to make good
decisions depends on honesty about scientific uncertainties combined with open
public discussion of the full range of alternatives available to us. ========================== * Rachel Massey is a consultant to Environmental Research
Foundation. ** Thanks to Audrey Thier of Environmental Advocates (www.envadvocates.org) for helping clarify several points in this issue. ========================== [1] "West Nile Virus Found in North Carolina,"
REUTERS, October 20, 2000. [2] John J. Howard and Joanne Oliver, "Impact of Naled
(Dibrom 14) on the Mosquito Vectors of Eastern Equine Encephalitis Virus,"
JOURNAL OF THE AMERICAN MOSQUITO CONTROL ASSOCIATION Vol. 13, No. 4 (December
1997), pgs. 315-325 [3] For information on resistance and alternative mosquito
control measures, see Environmental Advocates and others, "Toward Safer
Mosquito Control in New York State," January 2000, available at http://www.envadvocates.org/public_html/temp/mosquito.htm.
[4] David Pimentel, "Amounts of Pesticides Reaching
Target Pests: Environmental Impacts and Ethics." JOURNAL OF AGRICULTURAL
AND ENVIRONMENTAL ETHICS Vol. 8, No. 1 (1995), pgs. 17-29. [5] "Mosquito Control In and Around the House,"
fact sheet available at http://www.rci.rutgers.edu/~insects/sompam.htm;
"Mosquito Control in Maryland," fact sheet available at http://www.mda.state.md.us/mosquito/progdesc.biology
[6] "Biological Data on 25 Common Species of Mosquito
Found in Coastal North Carolina," North Carolina Public Health information
site, http://www.deh.enr.state.nc.us/phm/Pages/Biology.hm [7] For one example, see http://www.erie.gov/standing_water_form.phtml
[8] See U.S. Environmental Protection Agency,
"Mosquitoes: How to Control Them," available at http://www.epa.gov/pesticides/citizens/mosquito.htm
and "West Nile Virus: The Facts,"available at http://www.erie.gov/west_nile_virus.phtml
[9] U.S. Environmental Protection Agency Office of
Prevention, Pesticides, and Toxic Substances. "Reregistration Eligibility
Decision (RED): DEET," Washington, D.C.: US EPA, September 1998, EPA
publication 738-R-98-010. Available at http://www.epa.gov/oppsrrd1/REDs/0002red.pdf
[10] Mark S Fradin, "Mosquitoes and Mosquito
Repellents: A Clinician's Guide," ANNALS OF INTERNAL MEDICINE Vol. 128
(June, 1998), pgs. 931-940. See www.acponline.org/journals/annals/01jun98/mosquito.htm.
[11] "Buzz Off," CONSUMER REPORTS Vol. 65, No. 6
(June 2000), pgs. 14-17. [12] Paul R. Epstein, "Is Global Warming Harmful to
Health?" SCIENTIFIC AMERICAN Vol. 283, No. 2 (August 2000), pp. 50-57. Well Mr. Helliker, when will you begin to discuss the
full range of (unregistered) alternatives that are currently available to safely
and far more effectively control pest problems in California? |
