Perchlorates in the environment - the key current issues

Abstract

The perchlorate anion has a unique and profound ability to inhibit iodine uptake by the human thyroid, with potential adverse effects on the growth and development of fetuses, infants, and children. Its occurrence, fate, metabolism, transport and toxicity have been subjects of intensive study for slightly more than a decade, but almost exclusively in the United States (see e.g. refs [1–3] for some reviews). Given its ubiquitous, modern use in ‘energetic applications’, however, it is almost certain that perchlorate contamination is much more widespread, especially in industrial nations, and a more internationally flavoured literature has just recently begun to emerge (e.g. refs [4–6]). At this juncture, an appropriate question might be: should perchlorate still qualify as an emerging contaminant of concern? In this Research Front, we present a series of papers from widely different perspectives in order to provide a starting point from which this question can be answered. The last five years or so have produced a renaissance of interest in the natural occurrence of perchlorate.A topic that for many years seemed no more than yet another curiosity (among many) associated with the unique soils and salt deposits of the Atacama Desert, Chile. [7] In 2005, the journal Environmental Science and Technology recognised Dasgupta et al.’s very important paper on atmospheric formation of perchlorate [8] as its ‘research article of the year’, greatly widening awareness of this reemerging field. But a key question remains: How is perchlorate formed in the atmosphere? In the first of two opinion essays, Roberts [9] offers an atmospheric chemist’s perspective on the more likely scenarios for natural perchlorate formation in the troposphere or stratosphere or both. This paper should help sharpen the focus of the research agenda on the atmospheric chemistry of perchlorate. In the second essay, Dasgupta [10] makes a case that the recent focus on perchlorate may have actually served to divert attention away from a broader and more significant public-health problem – iodine deficiency. In my review, [11] I have attempted to first present a broad overview of the topic, largely for the benefit of readers new to the field. The final, somewhat more detailed section on natural occurrence and microbial attenuation aims to highlight the many