ASSOCIATION BETWEEN WASTE MANAGEMENT AND CANCER IN COMPANION ANIMALS

Background: Waste management in the Campania region is a major concern. Increased cancer rates have been documented in people residing in areas nearby Naples characterized by illegal dumping and waste incineration. Hypothesis: Dogs and cats residing in areas under direct influence of waste disposal have an increased cancer risk with respect to pets living in unexposed areas. Animals: 453 cancer cases and 1554 controls. Methods: Hospital-based case-control study in Naples (unexposed) and nearby cities having a history of illegal waste dumping (exposed). Tumor frequency was compared between the two areas and relative risks were calculated for various malignancies. Results. A 22% increased risk for cancer development was identified in dogs but not in cats residing in exposed areas (P < 0.05). An approximately 2-fold increased frequency of canine lymphoma cases (P < 0.05) accounted for the elevated tumor risk in dogs residing in exposed areas. The relative frequency of concurrent malignancies, leukemia, mast cell tumour, hepatic tumours, mammary cancer, hemangiosarcoma, osteosarcoma and other sarcomas did not differ in pets residing in exposed or unexposed areas. Conclusions and Clinical Importance: Waste emission from illegal dumping sites increases cancer risk in dogs residing in exposed areas. An increased prevalence of lymphoma has been previously recognized in humans living close to illegal waste dumps. Thus, epidemiological studies of spontaneous tumours in dogs may provide insight into the role of environmental factors in canine and human cancers and may predict health hazards for humans.