Ammonium perchlorate

Endpoint summary

Additional information

Because perchlorate is highly water soluble, most of the focus with regard to environmental problems has been on groundwater contamination and subsequent off-site migration in groundwater or surface water. As such information addressing the exposure of terrestrial wildlife to perchlorate is limited and, of that available, most is derived from controlled laboratory studies.

Very high concentrations of perchlorate (percent levels) are rare in the general terrestrial environment, occuring primarily at manufacturing facilities or at sites that tested or burned formulations or explosives containing high concentrations of hte oxidizer. Soil at other locations may contain trace levels (µg/kg) of perchlorate. The best example at the local level would be areas that were routinely used as an ignition platform for fireworks displays. Perchlorate is also used as an oxidizer in roadside flares, so very limited soil exposure may occur in areas where flares are used (or ditches that may have recived stormwater runoff from these areas).

In an EPA review carried out in 2002 (Perchlorate Environmental Contamination: Toxicological Review and Risk Characterization, 534 p) the following conclusions are made about perchlorate terrestrial exposures:

Terrestrial Organisms

Plants

The only available phytotoxicity information comes from 28-day seedling growth tests of lettuce (Lactuca sativa) performed in soil and sand cultures with sodium perchlorate (EA Engineering, Science and Technology, Inc., 1998). Although the exposure was to sodium perchlorate solution added to the solid media, the results may be expressed as milligrams per kilogram soil or sand, wet weight, or as milligrams per liter of irrigation solution. Growth was a more sensitive response than germination or survival. The quartile inhibitory wet-weight concentrations (IC25s) for growth in soil and sand were 78 mg/kg (293 mg/L) and 41 mg/kg (160 mg/L), respectively. Survival was reduced 26% at 420 mg/kg (2,520 mg/L) in soil and 39% at 180 mg/kg (840 mg/L) in sand. To account for interspecies variance, a factor of 10 is applied to the lowest IC25 11 to obtain a screening benchmark of 4 mg/kg as a wet-weight concentration in soil (or 16 mg/L as a concentration in irrigation solution).

Soil Invertebrates

The only available toxicity data for soil invertebrates is a 14-day acute lethality test of the earthworm (Eisenia fetida) performed in artificial soil irrigated with sodium perchlorate. The LC50 at both 7 and 14 days was 4,450 mg/kg as a wet-weight concentration in soil. No factors or other models are available to extrapolate from that LC50 to chronic effects on survival, growth, or fecundity or to extrapolate from this species to the soil invertebrate community as a whole.

Birds

Researchers have evaluated the effect of perchlorate exposure on bobwhite quail, both adults and chicks, and mallard duckling. These studies have focused on exposure via drinking water. At 0.12 mg/L, highest dose tested, no effect of perchlorate on the production of eggs, body or organ weights of the birds were noticed. Main effects are notices on endocrine system but birds have the ability to readily adapt to agents that may affect normal levels of hormones.