Correction to: Acute aquatic toxicity of tire and road wear particles to alga, daphnid, and fish.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Comparative sensitivity of field and laboratory populations of Hyalella azteca to the pyrethroid insecticides bifenthrin and cypermethrin.

Hyalella azteca are epibenthic invertebrates that are widely used for toxicity studies. They are reported to be more sensitive to pyrethroid insecticides than most other test species, which has prompted considerable use of this species in toxicity testing of ambient surface waters where the presence of pyrethroids is suspected. However, resident H. azteca have been found in some ambient water bodies reported to contain surface water and/or sediment pyrethroid concentrations that are toxic to laboratory reared H. azteca. This observation suggests differences in the sensitivities of laboratory reared and field populations of H. azteca to pyrethroids. The goal of the present study was to determine the sensitivities of laboratory reared and field populations of H. azteca to the pyrethroids bifenthrin and cypermethrin. Specimens of H. azteca were collected from resident populations at field sites that are subject to varied land-use activities as well as from laboratory populations. These organisms were exposed to bifenthrin- or cypermethrin-spiked water in 96-h water-only toxicity tests. The resulting data demonstrated that: 1) field-collected populations in urban and agricultural settings can be >2 orders of magnitude less sensitive to the pyrethroids than laboratory reared organisms; 2) field-collected organisms varied in their sensitivity (possibly based on land-use activities), with organisms collected from undeveloped sites exhibiting sensitivities similar to laboratory reared organisms; and 3) the sensitivity of field-collected "tolerant" organisms increased in subsequent generations reared under laboratory conditions. Potential mechanisms for these differences are discussed.

Acute aquatic toxicity of tire and road wear particles to alga, daphnid, and fish.

Previous studies have indicated that tire tread particles are toxic to aquatic species, but few studies have evaluated the toxicity of such particles using sediment, the likely reservoir of tire wear particles in the environment. In this study, the acute toxicity of tire and road wear particles (TRWP) was assessed in Pseudokirchneriella subcapita, Daphnia magna, and Pimephales promelas using a sediment elutriate (100, 500, 1000 or 10000 mg/l TRWP). Under standard test temperature conditions, no concentration response was observed and EC/LC(50) values were greater than 10,000 mg/l. Additional tests using D. magna were performed both with and without sediment in elutriates collected under heated conditions designed to promote the release of chemicals from the rubber matrix to understand what environmental factors may influence the toxicity of TRWP. Toxicity was only observed for elutriates generated from TRWP leached under high-temperature conditions and the lowest EC/LC(50) value was 5,000 mg/l. In an effort to identify potential toxic chemical constituent(s) in the heated leachates, toxicity identification evaluation (TIE) studies and chemical analysis of the leachate were conducted. The TIE coupled with chemical analysis (liquid chromatography/mass spectrometry/mass spectrometry [LC/MS/MS] and inductively coupled plasma/mass spectrometry [ICP/MS]) of the leachate identified zinc and aniline as candidate toxicants. However, based on the high EC/LC(50) values and the limited conditions under which toxicity was observed, TRWP should be considered a low risk to aquatic ecosystems under acute exposure scenarios.

A comparison of the copper sensitivity of six invertebrate species in ambient salt water of varying dissolved organic matter concentrations.

The copper sensitivity of four saltwater invertebrates (the mussel Mytilus galloprovincialis, the oyster Crassostrea virginica, the sand dollar Dendraster excentricus, and the sea urchin Strongylocentrotus purpuratus) was determined experimentally using chronic-estimator embryo-larval test procedures. The effect of sample dissolved organic matter (DOM) content on Cu bioavailability was determined for these species using commonly prescribed test procedures. Comparisons were made among these test results and test results reported previously for two other invertebrate species: the mussel Mytilus edulis and the copepod Eurytemora affinis. All six species exhibited a direct and significant relationship between the sample dissolved organic carbon (DOC; a surrogate measure of DOM) and either the dissolved Cu median lethal concentration (LC50) values or median effect concentration (EC50) values. This relationship is significant even when the DOM has different quality as evidenced by molecular fluorescence spectroscopy. Once normalized for the effects of DOM, the Cu sensitivity of these species from least to most sensitive were E. affinis < D. excitricus < C. virginica approximately S. purpuratus approximately M. edulis approximately M. galloprovincialis. This ranking of species sensitivity differs from the saltwater species sensitivity distribution proposed in 2003 by the U.S. Environmental Protection Agency. These results support the need to account for factors that modify Cu bioavailability in future saltwater Cu criteria development efforts. More specifically, Cu saltwater species sensitivity distribution data will need to be normalized by factors affecting Cu bioavailability to assure that accurate and protective criteria are subsequently developed for saltwater species and their uses.

Toxicity of anionic polyacrylamide formulations when used for erosion control in agriculture.

Addition of anionic polyacrylamide (PAM) to agricultural irrigation water can dramatically reduce erosion of soils. However, the toxicity of PAM to aquatic life, while often claimed to be low, has not been thoroughly evaluated. Five PAM formulations, including two oil-based products, one water-based product, one granular product and one tablet product, were evaluated for acute and/or chronic toxicity to five species commonly used for freshwater toxicity testing [Hyalella azteca (Saussure), Chironomus dilutus (Shobanov et al.), Ceriodaphnia dubia (Richard), Pimephales promelas (Rafinesque), and Selenastrum capricornutum (Printz)]. When applied as an oil-based product, acute toxicity was seen to four of the five species at concentrations less than the 10 mg/L that is often used for erosion control. Toxicity was diminished, but still remained, after passage of the irrigation water across an agricultural field, indicating a potential impact to nearby surface waters. Results from the non-oil-based products indicated minimal toxicity associated with PAM even at concentrations 10 times those used in agriculture when applied in the granular form, as a tablet, or in a water-based liquid. These data suggest that other agents in the oil-based products, such as surfactants or emulsifiers, rather than the PAM itself, contribute to the toxicity. Care is required in selecting an appropriate PAM formulation when the potential exists for entry of tailwater to nearby surface waters.

Aquatic effects of aerial spraying for mosquito control over an urban area.

In an effort to combat West Nile Virus, planes dispersed insecticide over Sacramento, CA, treating nearly 50,000 hectares with pyrethrins and the synergist piperonyl butoxide (PBO). Widespread dispersal of insecticide over a metropolitan area, coupled with extensive pretreatment data on the area's urban creeks, provided a unique opportunity to study effects of mosquito control agents on aquatic habitats within an urban setting. There was no evidence of aquatic toxicity from the two active ingredients in the product applied. However, PBO concentrations were high enough to enhance toxicity of pyrethroids already existing in creek sediments from general urban pesticide use. PBO concentrations of 2-4 microg/L were high enough to nearly double the toxicity of sediments to the amphipod Hyalella azteca. Though the increase in toxicity was modest, it was unexpected to find environmental synergy at all. Risk assessments for mosquito control agents have focused on the active ingredients but have failed to recognize the potential for interactions with pesticides previously existing in the environment, which in this case appeared to represent a risk to aquatic life greater than that of the active ingredients themselves.