Herbicide Exposure and the Risk of Transitional Cell Carcinoma TCC of the Urinary Bladder in Scottis

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Herbicide Exposure and the Risk of Transitional
Cell Carcinoma (TCC) of the Urinary Bladder in
Scottish Terrier Dogs

• LT Glickman, VMD, DrPH M Raghavan, DVM, PhD
• DW Knapp, DVM, MS, DACVIM PL Bonney, RVT MH
  Dawson, DVM
• School of Veterinary Medicine, Purdue University,
  West Lafayette, IN, USA
• Presentation by M Raghavan, DVM, PhD
• Study funded in part by the Scottish Terrier Club
  of America and the American Kennel Club Canine
  Health Foundation

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Cancers and herbicides

• Role of herbicides in the etiology of cancer is
  controversial
• Humans
• non-Hodgkins lymphoma (Phenoxy acids)
• Soft tissue sarcoma (Phenoxy acids)
• Dogs
• Canine malignant lymphoma (2,4-D--a phenoxy acid)

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TCC of the urinary bladder

• Risk factors in dogs
• Female
• Neutered
• Overweight/obese
• Flea / tick products (dips)
• Known risk factors in humans
• Cigarette smoking
• Aromatic amines (dye industry)
• Ionizing radiation
• Possible high-risk occupations
• Gardeners
• Nurserymen
• Hairdressers
• Etiology multifactorial
• Genetic (GSTM1 gene)
• Environmental

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Purpose of study

• Objective
• To determine if
• exposure to specific lawn or garden pesticides
  increases the risk of TCC in Scottish Terriers.
• Hypothesis
• TCC is associated with
• owners use of lawn or garden pesticides
• herbicides (2,4-D)

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Materials Methods

• Case control study
• Starting June, 2001
• Cases Scottish Terriers with TCC of urinary
  bladder
• Diagnosis
• Biopsy or cytology
• Pathology reports required
• 1/95 1/03
• Controls Scottish Terriers with other health
  problems including other cancers
• 6 years of age
• No urinary tract disease for 2 years
• One case or one control per household

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Materials Methods

• Owner questionnaire
• Lifetime diet, dietary supplements
• Management, husbandry
• Health, medications
• Chemical exposures
• Commonly used household and lawn/garden
  pesticides
• Brand names, active ingredients
• Pesticide exposure
• Cases one year prior to diagnosis
• Controls comparable time period
• Statistical analysis
• Logistic regression
• Odds Ratio (likelihood of TCC in exposed versus
  non-exposed)
• Significance at p lt 0.05

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Description of study population
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83 Cases of TCCDiagnostic Methods
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Access to lawns or gardens and risk of
TCC(Univariate logistic regression)
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Exposure to lawns or gardens treated with
pesticides
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Exposure to lawn or garden pesticides and risk of
TCC(Univariate logistic regression)
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Type frequency of herbicide applications and
risk of TCC(Univariate logistic regression)
P-value test for trend 0.00002
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Exposure to lawn or garden pesticides and risk of
TCC in 131 Scottish Terriers with access to lawns
or gardens (Multivariate logistic regression)
Adjusted for age, neuter status, coat color,
weight, and access to lawns or gardens
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Active ingredients in herbicides and risk of TCC
in 130 Scottish Terriers with access to lawns or
gardens (Multivariate logistic regression)
Adjusted for age, neuter status, coat color,
weight, and access to lawns or gardens treated
with insecticides
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Inert ingredients in pesticides

• Any ingredient other than an active ingredient
• Solvents, surfactants, carriers, etc.
• Examples
• Toluene, Xylene, Benzene, Petroleum distillates,
  Rhodamine B
• Usually gt 50 by volume (1 99)
• No requirement for listing on label (proprietary)
• Chemically, physically, or toxicologically active
• Many are health hazards (i.e., carcinogens)

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• Conclusions
• Exposure to lawns or gardens treated with
  herbicides increase the risk of TCC in Scottish
  Terrier dogs
• Strength of association
• Dose response
• Inert rather than active ingredients may be
  responsible
• Recommendations
• Access to lawns or gardens treated with phenoxy
  or non-phenoxy herbicides should be reduced until
  additional risk studies are done