Evaluation of uranium incorporation from contaminated areas using teeth as bioindicators--a case study

Abstract

The Southwest region of the Bahia state in Brazil hosts the largest uranium reserve of the country (100 kton in uranium, only), plus the cities of Caetité, Lagoa Real and Igaporã. In this work, aim was at the investigation of uranium burdens on residents of these cities by using teeth as bioindicators, as a contribution for possible radiation protection measures. Thus, a total of 41 human teeth were collected, plus 50 from an allegedly uranium free area (the control region). Concentrations of uranium in teeth from residents of 5- to 87-y old were determined by means of a high-resolution inductively coupled plasma mass spectrometer (ICP-MS). The highest uranium concentration in teeth was measured from samples belonging to residents of Caetité (median equal to 16 ppb). Assuming that the uranium concentrations in teeth and bones are similar within 10-20% (for children and young adults), it concluded that uranium body levels in residents of Caetité are at least one order of magnitude higher than the worldwide average. This finding led to conclude that daily ingestion of uranium, from food and water, is equally high.

Evaluation of Uranium in Organs of Residents from an Uranium-Rich Region using Teeth as Bioindicators

“…As pointed out elsewhere [1][2][3][4], wastes from the Caetité plant are categorized mostly as: (a) wastes from the mining operations which include waste rock and drainage waters, and (b) wastes from the industrial process, that is, leached ore and ef luents from the milling plant. In fact, contamination of groundwater by the waste ponds is of great concern, where elevated levels of 238 U have been observed.…”

“…and drinking water must therefore be considered in the case of this uranium-rich region. Such a scenario motivated an investigation of Uranium concentrations in teeth of residents (5 to 87 years old) of this region, carried out at this Laboratory using a high-resolution inductively coupled plasma mass spectrometer (ICP-MS) [2]. The highest Uranium concentration in teeth was measured from samples belonging to residents of Caetité (median equal to 16 ppb).…”

“…The highest Uranium concentration in teeth was measured from samples belonging to residents of Caetité (median equal to 16 ppb). However, since Uranium concentrations in teeth and bones are similar, particularly for children and young adults, the Uranium body levels in residents of Caetité are, thus, quite high -actually, at least one order of magnitude higher than the worldwide average for bones [2]. Uranium concentrations in organs like bones and teeth are correlated with the amount of Uranium present in ingested food and water.…”

“…Teeth are good long-term (chronic) exposure monitors, working as reservoirs for many metals incorporated from the environment [3], and their metabolical similarity with bones, as pointed out above, allows the evaluation of contaminants accumulation in the skeleton [2].…”

Modes of action associated with uranium induced adverse effects in bone function and development

“…In humans and animals, uranium deposits in the skeleton in a dose-and timedependent fashion (Arruda-Neto et al, 2004;Lariviere et al, 2013;Pellmar et al, 1999;Prado et al, 2008) and uranium accumulation in bones occurs at a higher rate in young individuals (Lariviere et al, 2007;Rodrigues et al, 2013). Thus, bone is considered to be the most significant, long term deposit of uranium.…”