APPENDIX II-AC: Blood Brain Barrier Goode


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Subject:   Coming Clean: A Warning re Mosquito Control efforts from Dr. Dennis Goode
 Date:      Fri, 13 Jul 2001 09:43:45 -0400
From:        Stephen Tvedten <>
Organization:     Get Set Inc. (

To:     Paul Helliker <>
          Director, State of California, Department of Pesticide Regulation 

cc:    Christine Whitman

Dear Mr. Helliker, I thought you might like to read a report entitled: Coming Clean: A Warning re Mosquito Control efforts from Dr. Dennis Goode. 

This is from Dr. Dennis Goode, Department of Biology, University of Maryland, who presented this information to the officials at the Maryland Department of health. He says West Nile Virus "in general is a mild disease" unless it crosses the blood-brain barrier. He warns that pesticides can damage the blood-brain barrier making entry of WNV more possible. He also asserts that spraying pesticides makes the situation worse not only because of this but because of other serious health effects of pesticides which he cites with substantiating medical research documents. 

Howard County Department of Health 

June 20.2001 

From: Dr. Dennis and Judith Goode

Re: West Nile Virus Management Plans 

Our major concern is that the adverse health effects of spraying may be greater than the effects of the West Nile virus (WNV). The New York State Health Department figures released last week show that many more people became sick from last year's WNV pesticide spraying than from the virus. Over 200 people reported symptoms from the mosquito spraying compared to 14 who became ill from the virus (1). 

The pyrethroid insecticides proposed for adulticide spraying, permethrin and sumithrin, block nerve sodium channels in an open configuration and lead to prolonged or repetitive nervous stimuli that paralyze and eventually kill insects(2).  The effects on humans are similar at the cellular level. Inhaling pyrethroids can initiate headaches, asthmatic attacks, tremors, and convulsions. Sustained impulses can lead to axonal degeneration (3).  Extensive exposures can produce nervous system disorders, acquired sensitivities to pyrethroids and other chemicals, and scleraderma-like syndromes(3). 

Pyrethroids are suspected carcinogens that stimulate proliferation of breast cancer and prostate cancer cells (8) and are linked to childhood brain cancer. "The specific chemicals associated with children's cancers were pyrethrins and pyrethroids (which are synthetic pyrethrins such as permethrin ---) and chlorpyrifos"(4).  The synergist piperonyl butoxide (PBO) added to pyrethroid mosquito sprays is also a suspected carcinogen, as well as an inhibitor of cytochrome P450 system enzymes needed to break down pyrethroids and other toxins. Thus, PBO leads to greatly elevated and prolonged exposure of tissues to the toxins(5). 

In general WNV is a mild disease. It only becomes serious encephalitis if the virus can cross the blood-brain barrier(6).  Among the agents that impair the blood-brain barrier in young rats are pyrethroid, organophosphate, and organochlorine pesticides(7). 

Thus, insecticide spraying has the potential to worsen the process of WNV infection. 


1. Wood, S. and D. Cappiello (2001). Feeling the sting of West Nile spraying. Albany Times Union, June 15, 2001. 

2. National Research Council (1992). Environmental Neurotoxicology. pp. 34-35. National Academy Press, Wash. D.C. 

Muller-Mohnssen, H. (1999). Chronic sequelae and irreversible injuries following acute pyrethroid intoxication. Toxicol. Letters 107: 161-175. Smith, K.J. and S.M. Hall (2001). Factors directly affecting impulse transmission in inflammatory demyelinating disease. Curr. Opin. Neurol. 14: 289-298. 

4. Pogoda, J.M. and S. Preston-Martin (1997). Household pesticides and the risk of pediatric brain tumors. Envir. Health Perspect. 105(11): 1214-1220. 

5. Kakko, I. et al. (2000). Piperonyl butoxide potentiates the synaptosome ATPase inhibiting effect of pyrethrin. Chemosphere 40: 301-305. Shykla, A. and N.S. Radin (1990). Metabolism of an inhibitor of glucosylceramide synthesis and the synergistic action of an inhibitor of microsomal monooxygenase. J. Lipid Res. 32: 713-722. 

6. Ben-Nathan, D. et al. (1996). West Nile virus neuroinvasion and encephalitis induced by macrophage depletion in mice. Arch. Virol. 141: 459-469. Ben-Nathan, D. et al. (2000). CNS penetration by noninvasive virus following inhalational anesthetics. Ann. N.Y. Acad. Sci. 917: 944-950. 

7. Gupta, A. et al. (1999). Effect of pyrethroid-based liquid mosquito repellent inhalation on the blood-brain barrier function and oxidative damage in selected organs of developing rats. J Appl. Toxicol. 19:67-72. 

8. Tessier, D.M. and F. Matsumura. (2001). Increased ErbB-2 tyrosine kinase activity, MAPK phosphorylation, and cell proliferation in the prostate cancer cell line LNCaP following treatment by select pesticides. Toxicol. Sci. 60: 38-43. 

Dr. Dennis Goode
University of Maryland