HCH contamination from former pesticide production in Brazil--a challenge for the Stockholm Convention implementation.

Hexachlorocyclohexane (HCH) isomers (α-, ß- and γ- HCH [lindane]) were recently added to the list of persistent organic pollutants regulated by the Stockholm Convention, and therefore, the legacy of HCH and lindane production has become an issue of global relevance. The production of lindane with the much larger quantities of associated waste isomers has generated large waste deposits and contaminated sites. This article presents an overview of HCH-polluted sites in Brazil as a basis for further activities related to the Stockholm Convention. The locations of HCH stockpiles and contaminated sites in Brazil arising from production and formulation have been compiled and mapped. This shows that the measures taken over the past 25 years have not resulted in remediation of the HCH pollution. An exposure risk study has been summarised for one major site and is included to demonstrate the contemporary relevance of the contamination. Major site remediation efforts are planned at one site but people live close to several other sites, and there is an urgent need of further assessments and remediation to ensure the protection of human health and the environment. The Stockholm Convention requires a systematic approach and should be adopted for the assessment of all sites and appropriate isolation/remediation measures should be facilitated. The appropriate planning of these activities for the production site in Rio de Janeiro could be a positive contribution for Rio+20 highlighting that green economy and sustainable production also include the appropriate management of legacies of historic production of an industrial sector (here the organochlorine industry).

Occult T wave alternans in long QT syndrome.

T wave alternans that is visually apparent on the ECG is a known risk factor for sudden death in idiopathic long QT syndrome (LQTS). To determine if occult and visually undetectable forms of T wave alternans are also present in LQTS, we measured T wave alternans from a 16-year-old girl with LQTS during exercise using spectral analysis methods and a recording system designed to minimize exercise-related noise. While there was no alternans at rest, statistically significant, yet visually inapparent T wave alternans were measured both during exercise and recovery. Using identical recording techniques, no significant T wave alternans was detected from the subject's mother, who had a prolonged QT interval but was not experiencing arrhythmias, nor from five healthy volunteers with normal QT intervals. This report suggests that electrocardiographically occult, yet prognostically important forms of T wave alternans may be present in patients with LQTS.

Independent ablation of retrograde and anterograde accessory connection conduction at the atrial and ventricular insertion sites: evidence supporting the impedance mismatch hypothesis for unidirectional block.

INTRODUCTION: The impedance mismatch hypothesis has been proposed as one of the mechanisms responsible for accessory connection conduction block. METHODS AND RESULTS: We describe a case in which retrograde conduction across a posteroseptal accessory connection was ablated at the atrial insertion site in the coronary sinus os, whereas anterograde conduction was ablated at the ventricular insertion site in the left ventricle. CONCLUSION: The evidence supports the impedance mismatch concept as the cause of unidirectional conduction block and shows that the distal junction between the accessory connection and the myocardium is more vulnerable to ablation.