Almost 30 years after its introduction, the "circle of poison" remains a common conceptualization of the global pesticide complex among scholars and especially in popular understanding. The circle of poison describes a situation in which, pesticides banned in industrialized countries continue to be manufactured there and exported to developing countries, are then used in developing countries almost entirely on export crops, and return to industrialized countries as pesticide residues on food. Using secondary data and a case study of pesticide use in Costa Rica, I review the applicability of the circle of poison conceptualization to the current global pesticide complex. I argue that (1) the circle of poison is no longer accurate due to important global changes in pesticide regulation, production, trade, sales, and use driven by a number of dynamic economic, social, and ecological processes; (2) using industrialized countries' pesticide regulations as proxies for safety should be replaced by multi-characteristic risk assessments; and (3) revisions of the circle of poison conceptualization should be updated because of export farmers' adoption of newer classes of pesticides. The paper concludes by offering a new characterization of the global pesticide complex vis-à-vis pesticide use in developing countries: pesticide divergence by market orientation. © 2008 Elsevier Ltd. All rights reserved.

Using a critical cartography/GIS approach and multiple data sets on community supported agriculture (CSA), this paper addresses two questions. First, how accurate was the 2007 United States Census of Agriculture's counting of CSAs? Second, where are CSAs concentrated and how does their distribution compare with that of farming generally and population distribution? I argue that significant overcounting of CSAs in the census occurred largely because of a lack of shared meanings of terms. Examination of discrepancies between data sets at the county level in California points to higher CSA overcounting in counties with many farms and lower overcounting in counties with many CSAs. This overcounting matters as critical geographers and others increasingly seek to take stock of and contribute to alternative agrifood movements. As for distribution, multi-scale maps and a CSA density indicator reveal the continued existence of high levels of CSAs in New England and the Pacific Northwest and low levels in the South. Further data collection and analysis efforts should focus on (1) improving census questions for the next CSA count, including adding a definition of CSA and asking whether farmers coordinate the CSA or contribute to a joint CSA; and (2) conducting further geographical analyses on CSA vis-à-vis contributing causes behind low and high concentrations and areas of fast and slow growth.

In the United States, the Environmental Protection Agency (EPA) registers pesticides and sets crop-specific tolerances while the Food and Drug Administration (FDA) enforces EPA regulations by testing plant-based foods for pesticide residues. Pesticide treatment histories are almost always unknown, especially on imported produce, posing an empirical question: to what extent do FDA's residue testing methods used on imported produce correspond to the pesticides used on the crops? In this article I show that FDA residue testing would have missed residues of the majority of pesticides used on two crops exported to the US from Costa Rica in 2003, suggesting that FDA residue testing on imported produce is inadequate in its coverage. Policy recommendations discussed include better communication of US tolerances to exporters around the world; increased testing for pesticides, especially fungicides, that are currently not part of FDA's regular testing procedures; and the creation of price floors and fair trade relationships in the transnational vegetable market to support farmers' attempts to comply. © 2009 Elsevier Ltd. All rights reserved.

In a globalizing economy, agri-food regulation in the industrialized world increasingly affects food-producing industries and farmers in developing countries. Discussions of these transformations remain mostly disconnected from the literature on pesticide use in developing countries, which emphasizes widespread pesticide misuse and abuse. Previous attempts to consider the relationship between agri-food regulation and farmers' pesticide use are found lacking because they do not situate it deeply enough within the social relations of exchange in contract farming. Using a political ecological approach attentive to this relationship, I found many farmers exercising considerable caution in their pesticide use vis-à-vis residues on mini-squash and chayote, the main export crops in Northern Cartago and the Ujarrás Valley, Costa Rica. Exporters' mediation of regulatory risk - conceptualized as the possibility that an actor's behaviour will be subject to state regulation and that out of compliance behaviour will result in negative consequences that impact the actor - largely explains why this type of caution occurs. A gap between regulation and practice persists, however, because of the local history of residue violations and a related misinterpretation of pesticides' colour bands. The conclusion critiques the first world/third world binary that is mapped onto pesticide use research as preventing advancements in understanding farmers' pesticide use, shows the applicability of political ecology's chain of explanation to the local consequences of agri-food regulation from afar and proposes further engagement between agri-food studies and political ecology to better theorize local-global interactions between land users and the new spatiality of economic governance in agri-food networks. © 2007 The Author. Journal compilation © Royal Geographical Society (with The Institute of British Geographers) 2007.

Nicotinic acetylcholine receptors (nAChRs) are ligand- gated ion channels that mediate rapid neurotransmission in the central and peripheral nervous systems. The acetylcholine binding protein (AChBP) is a soluble structural and functional surrogate of the extracellular, ligand-binding domain of the nAChR that allows for studies not amenable to study of the nAChR as an integral membrane protein. In particular, AChBP provides a system in which to study solution dynamics and conformational changes related to ligand binding. To deduce ligand binding sites and infer conformational changes, cysteine mutants of AChBP were generated and labeled with the solvent- sensitive fluorophore, acrylodan. The fluorescence emission spectra from acrylodan-labeled AChBP mutants were examined in the absence and presence of nicotinic ligands. Binding of small molecules and large peptide toxins caused acrylodan conjugated to Q178C to move into environments of opposite polarities. From this, I proposed a hinge position at Q178 that allows for flexibility of the C-loop, such that it can expand or contract as a rigid body to accommodate bound ligand. Distinctive changes in acrylodan emission were also observed in the F-loop, indicating that this region of the protein likely plays a role in ligand binding, a finding not evident from existing structures. Complementary hydrodynamic and fluorescence anisotropy studies of AChBP free in solution and in complex with an 8 kD three-fingered alpha-neurotoxin indicated that the bound alpha-toxin has minimal effects on the translational and rotational diffusion properties of AChBP. Anisotropy experiments showed that, when bound, the alpha-toxin is highly dynamic. Its central finger, that contains beta- sheet structure and interacts with the agonist binding site, is the most rigid portion. The segmental flexibility of AChBP was studied by measuring decay of fluorescence anisotropy from fluorescein-labeled AChBP mutants. The results revealed that AChBP exhibits wide regional variation in alpha-carbon backbone flexibility, with the C -loop being overall most rigid in the picosecond- nanosecond time domain. In studying the effect of ligand binding on conformational flexibility, we found that the F -loop conformational change associated with ligand binding is pharmacologically correlated. Solution-based structural studies of conformation related to ligand binding should facilitate structure-guided drug design and increase understanding of nAChR function

In this paper, I review recent political ecological scholarship on first world agrifood systems and advocate for further development of the field. To do so, I first briefly examine the themes of first world political ecology and argue that food systems is an underdeveloped topic in first world political ecology relative to other themes because of the existence of agrarian political economy, a strongly allied field. This requires interrogating and teasing apart the relationship between political ecology and agrarian political economy. I then turn to review the current "political ecology of first world food systems" literature, which is both in line with established political ecological contours - examining global-local connections, conservation and degradation, and the utility of ecological metrics - but also recently extending analysis to alternative food networks and to the body-consumption nexus. In the conclusion, I outline an agenda for political ecological research praxis focused on increased interdisciplinary work with biophysical and technical scientists; the spatial, social, economic margins; the "invisible middle" of the food industry and the "end" of the food system in human waste and the necessity of mending the metabolic rift; and the need for increased societal engagement by political ecologists. © 2013 The Author(s) Geography Compass © 2013 John Wiley & Sons Ltd.

Understanding the factors that influence the adoption of synthetic pesticides has to date overshadowed explanations of variation in pesticide intensity. I conducted a survey of vegetable farmers in Northern Cartago and the Ujarrás Valley, Costa Rica, in 2003-2004 with the goal of explaining differences in pesticide intensity with reference to socioeconomic, political economic, and agroecological characteristics and relationships. Using ordinary least squares regression models, this paper explores the factors that influence pesticide use intensity in potato and squash production. Results indicate that many variables strongly influence pesticide intensity, including variables related to the farmer, farm household, political-economic relationships, the biophysical environment, and agroecological relationships. Conclusions discuss the need for an integrated approach to adequately understand pesticide intensity and potential policy interventions including agroecological education and extension, increased enforcement of pesticide residue limits in the national market, and land reform to allow for longer fallow periods. © Springer Science+Business Media, LLC 2008.

The environmental impact of agro-export production in developing countries remains an important research topic. The political economy-inspired literature on developing country agro-exports maintains that export crops are pesticide intensive - or, more generally, environmentally destructive - while local and national market crops are less pesticide intensive, or environmentally benign. If used to draw conclusions about the impact of national market versus export market expansion, this view has significant limitations, most importantly the comparison of high-commodity value export crops with low-commodity value crops for national market. To overcome this and other limitations of prior analyses, this paper addresses the question: how does market orientation influence pesticide intensity where the same crops are grown for both the national market and for export? Data from a survey of Costa Rican vegetable farmers are used to compare pesticide intensity of 27 vegetable crops, five of which are produced for both national and export markets. The general pattern that emerges is that national market vegetables are more pesticide intensive than export vegetables in the area. Yet, controlling more for the crop variable is important, and specific comparisons of the five vegetables grown for both markets - carrot, chayote, corn, green beans, and squash - illustrate that market orientation alone does not determine pesticide intensity, but that it is jointly influenced by regulatory risk, crop value, and pest susceptibility, among other factors. Continued attention to both political economy and ecological processes in "second nature" will allow political ecology to make important contributions to understanding pesticide problems and implementing agroecological solutions. © 2007 Elsevier Ltd. All rights reserved.