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Abstract
Context. The case fatality from acute poisoning with glyphosate-containing herbicides is approximately 7.7% from the available studies but these have major limitations. Large prospective studies of patients with self-poisoning from known formulations who present to primary or secondary hospitals are needed to better describe the outcome from acute poisoning with glyphosate-containing herbicides. Furthermore, the clinical utility of the glyphosate plasma concentration for predicting clinical outcomes and guiding treatment has not been determined. Objective. To describe the clinical outcomes, dose–response, and glyphosate kinetics following self-poisoning with glyphosate-containing herbicides. Methods. This prospective observational case series was conducted in two hospitals in Sri Lanka between 2002 and 2007. We included patients with a history of acute poisoning. Clinical observations were recorded until discharge or death. During a specified time period, we collected admission (n = 216, including five deaths) and serial (n = 26) blood samples in patients. Severity of poisoning was graded using simple clinical criteria. Results. Six hundred one patients were identified; the majority ingested a concentrated formulation (36%, w/v glyphosate). Twenty-seven percent were asymptomatic, 63.7% had minor poisoning, and 5.5% of patients had moderate to severe poisoning. There were 19 deaths (case fatality 3.2%) with a median time to death of 20 h. Gastrointestinal symptoms, respiratory distress, hypotension, altered level of consciousness, and oliguria were observed in fatal cases. Death was strongly associated with greater age, larger ingestions, and high plasma glyphosate concentrations on admission (>734 μg/mL). The apparent elimination half-life of glyphosate was 3.1 h (95% CI = 2.7–3.6 h). Conclusions. Despite treatment in rural hospitals with limited resources, the mortality was 3.2%, which is lower than that reported in previous case series. More research is required to define the mechanism of toxicity, better predict the small group at risk of death, and find effective treatments.
Acknowledgments
We thank the study doctors and research coordinators for collecting data, gathering blood samples, and reviewing the medical records included in this study. We also thank the hospital physicians for their assistance and support of the study and the medical superintendents of General Hospital Anuradhapura and Polonnaruwa for allowing access to medical records.
The South Asian Clinical Toxicology Research Collaboration is funded by the Wellcome Trust/National Health and Medical Research Council International Collaborative Research Grant 071669MA. ME was a Wellcome Trust Career Development Fellow funded by grant GR063560MA. The funding bodies had no role in gathering, analyzing, or interpreting the data, or the writing of this manuscript, or the decision to submit.
ME, NAB, and AHD designed the clinical studies to which the patients were recruited. DMR, NAB, ME, FM, and AHD contributed to the collection of data and coordination of these studies. DMR, DAG, and FM arranged the collection and transport of plasma samples from Sri Lanka to the United States. DAG coordinated the analysis of the plasma samples which were conducted by AM and MSB who take responsibility for these data. DMR and FM coordinated the chart review. DMR extracted and analyzed the data and drafted the initial manuscript. All authors contributed to the final version of the manuscript and approve its submission. DMR coordinated the development of the manuscript, retains full access to the data presented, and had final responsibility for the decision to submit for publication.