Perchlorate in the United States. Analysis of Relative Source Contributions to the Food Chain

Abstract

Perchlorate has been considered by some a potential threat to human health, especially to developing infants and children because it may inhibit iodide uptake by the sodium iodide symporter (NIS) of the thyroid. In the United States, during the last several decades, environmental perchlorate has had three recognized sources stemming from (a) its use as an oxidizer (including in rocket propellants), (b) its presence in Chilean nitrate fertilizer (CNF), and (c) natural production. An analysis of the relative source strengths and how they may influence entry into the food chain has not been conducted. Averaged over the last --60 years, we estimate that the source strengths have been (a) 10.6, (b) 0.75, and (c) 0.13-0.64 Gg/y for the United States as a whole. Of this, while (b) and (c) represent actual dispersed amounts, the figure in (a) is the amount of perchlorate produced and only a fraction (f) of it has been dispersed and often in a more localized fashion. In addition, dispersal of (b) has taken place only over agricultural land. Considering that the total land area in the United States is 5.5 x the arable land area, in terms of incorporation into the food chain,the figure cited in (b) has a proportionately greater impact. Most estimates of fwill thus suggest that over the considered period, the contribution of CNF to incorporation of perchlorate in the food chain has likely been comparable to oxidizer perchlorate, with natural production being a lesser source. Fireworks presently constitute a potentially important source of increasing importance but a quantitative impact cannotyet be assessed.

Drinking water contribution to aggregate perchlorate intake of reproductive-age women in the United States estimated by dietary intake simulation and analysis of urinary excretion data

“…Nonetheless, we believe that our three hypothetical distributions cover a reasonable range of perchlorate concentrations. All are consistent with the UCMR1 data in the extreme upper percentiles, and with data from other regional studies showing widespread lower-level contamination from natural sources or fertilizer use (Dasgupta et al, 2006;Rajagopalan et al, 2006;Plummer et al, 2006;Rao et al, 2007). Another limitation of our dietary simulation is that data on perchlorate concentrations in food from the FDA Exploratory Survey are not a random national sample, but were taken from locations where the likelihood of perchlorate contamination was suspected to be high.…”

“…This contamination can arise from natural sources (Rajagopalan et al, 2006;Rao et al, 2007), diffuse releases from fertilizer use (Dasgupta et al, 2006;Rice et al, 2007), and localized contamination from explosives and fireworks (MDEP, 2006). Jackson et al (2004) found groundwater perchlorate concentrations greater than 0.5 mg/l in 46% of wells in west Texas and New Mexico.…”

US Food and Drug Administration's Total Diet Study: Dietary intake of perchlorate and iodine

“…In recent years, perchlorate and iodine have received a fair amount of attention in the scientific literature. Perchlorate is a chemical that is found to occur naturally in Chilean nitrate fertilizer, which has been used in the United States (Dasgupta et al, 2006). Perchlorate is also synthesized in the United States and used as an oxidizing agent in solid rocket propellant and found in other items (e.g., explosives, road flares, fireworks, car airbags, herbicides, and so on).…”

Perchlorate Behavior in a Municipal Lake Following Fireworks Displays

“…Other work proposes multiple possible sources of perchlorate to subsurface and surface environments such as mineralogical impurities, agricultural fertilizers, or in situ formation via electrochemical processes (27). Although fireworks are commonly referred to as a source of perchlorate to the environment (28)(29), few data are available to evaluate impacts to groundwater or surface water resources (30). For example, Dasgupta et al (29) note, in their recent examination of sources of perchlorate to the environment, that a knowledge gap exists regarding the relationship between fireworks displays and the environmental occurrence of perchlorate.…”

“…Although fireworks are commonly referred to as a source of perchlorate to the environment (28)(29), few data are available to evaluate impacts to groundwater or surface water resources (30). For example, Dasgupta et al (29) note, in their recent examination of sources of perchlorate to the environment, that a knowledge gap exists regarding the relationship between fireworks displays and the environmental occurrence of perchlorate. This paper documents the time-dependent concentrations of perchlorate observed in a municipal lake following four fireworks displays from 2004 to 2006.…”