According to conventional wisdom, rapidly growing stocks of scrap tires on the U.S.-Mexico border pose a variety of health and environmental risks. This article assesses these risks in Paso del Norte, the border's second-largest metropolis comprised principally of Ciudad Juárez, Chihuahua, and El Paso, Texas. We find that air pollution from tire pile fires poses the greatest threat. Scrap tires in Paso del Norte do not contribute significantly to the propagation of mosquito-borne diseases or to shortages of space in solid waste disposal sites. The burning of scrap tires at industrial facilities is minimal and might not have significant adverse environmental impacts even if it were more common.

The increasing stringency of world food markets requires farmers to adjust farm structure and commercial strategies to remain integrated in export supply chains. The goal of this study was to identify and characterize different types of fresh fruit farms with regard to farm structural and commercial strategies for a representative sample of fresh fruit growers from central-south Chile exporting to world markets. A typology of farms was constructed based on multivariate analysis, according to which five types of farms were differentiated from five distinct factors. Cluster I comprised the smallest and uncertified farms (14.3% of the sample). The remaining four clusters comprised certified farms, but with different farm structural and commercial characteristics. Cluster II (15.1%) was composed of farms located further from market connections. Cluster III (23.9%) comprised farms with the highest number of fruit species, and consequently, more diversified in fruit production. Cluster IV (8.8%) was the smallest group, and comprised the largest firms. Finally, Cluster V (37.8%) was composed of highly specialized fruit farms, with the highest proportion of hectares dedicated to the production of a single fruit species. The results show the heterogeneity among fresh fruit farms and support the need for differentiated incentives and technological transfer schemes from the public sector and fruit companies in order to successfully keep farmers within export supply chains.Additional key words: cluster analysis; commercial strategies; farm structure; farm typology; food chain; fresh fruit. * Corresponding author: lauranahuel@uach.cl Received: 27-08-12. Accepted: 14-03-13Abbreviations used: GAP (good agricultural practices); PCA (principal component analysis); SPS (sanitary and phytosanitary standards).