The authors' reply

Abstract

The authors' reply:We thank the authors of the 2 letters from the Costa Rica banana industry (E. Quirós, National Association of Banana Producers; S. Laprade, CORBANA) for their timely critique of our article "Pesticides in blood from spectacled caiman (Caiman crocodilus) downstream of banana plantations in Costa Rica" [1]. While the letters question several elements of our study design, analytical techniques, and interpretation of results, they also highlight one of the fundamental challenges faced in ecotoxicology-namely, documenting cause-and-effect relationships when assessing complex mixtures of pesticides in the environment.The real world of contaminant mixtures continues to confound risk assessors, managers, and conservationists around the world and has been the subject of much discourse [2][3][4]. In this regard, our study was an easy target; spectacled caiman are omnivorous predators, occupying high trophic levels in the remote rain forest of the North Atlantic Zone of Costa Rica. Establishing a link between pesticides applied in nearby banana plantations and effects on the health of this top predator is fraught with difficulty. Mr. Quirós queried why we would not "consult with representatives of the banana sector in order to determine which products are used in our production system" when we designed our study. We did contact the industry for this information but received no response. We therefore followed suggestions from other scientists working on pesticides in Costa Rica as we designed our list of 70 target analytes for ultratrace high-resolution mass spectrometry of caiman blood. We agree that full disclosure of information on pesticide active ingredients, adjuvants, and application rates by the industry would indeed facilitate more meaningful research in the future.Working with free-ranging predators is not easy. We livecaptured caiman averaging approximately 1.4 m in length and 10 kg in mass in a remote rain forest in Costa Rica where there are no roads and few human settlements. Banana cultivation is the dominant agricultural activity in this area, covering 35 000 ha, compared with 13 000 ha for all other crops combined [5]. Bananas also represent one of the world's most pesticideintensive crops, with 46 kg of pesticide active ingredients applied per hectare of cropland [6][7][8]. While Mr. Quirós may feel that our approach was "biased" against bananas, we view it as hypothesis testing; we hypothesized that caiman inhabiting aquatic environments near major banana monocultures would be exposed to pesticides. We held no ulterior motives in setting this hypothesis, other than aiming to conduct research in support of protecting healthy habitats for endangered species found in the area.Regrettably, some of the criticisms presented by Mr. Laprade and Mr. Quirós detract from the subject at hand and in some cases misinterpret our work or are inconsistent with basic