Toxicity Identification Evaluation Approach Research Articles

Using a tiered approach based on ecotoxicological techniques to assess the ecological risks of contamination in a subtropical estuarine protected area

This study sought to assess the ecological risks of sediments from the northern portion of an estuarine protected area (Cananéia-Iguape-Peruíbe Protected Area — CIP-PA). The CIP-PA is located on the southern coast of São Paulo State, Brazil and is influenced by former mining activities along the Ribeira de Iguape River (RIR). We used a tiered approach based on multiple lines of evidence (geochemical analyses, toxicity tests, and whole sediment toxicity identification and evaluation) in order to assess environmental quality. The sediments presented a heterogeneous composition, but the samples collected close to the RIR exhibited higher concentrations of metals (Cd, Cr, Cu, Pb) and toxicity. Multivariate analysis showed that toxicity was associated with metals, mud, organic matter, and CaCO3 quantities. The whole-sediment toxicity identification evaluation approach indicated that ammonia and metals were responsible for sediment toxicity. Overall, we concluded that the sediments collected at depositional areas from the northern portion of the CIP-PA presented high levels of metals, which originated from former mining areas located in the upper RIR basin, and that this contamination had toxic effects on aquatic invertebrates. The tiered approach was useful for identifying the degradation of sediment quality and also for indicating the causes of toxicity. Because the CIP-PA is an important estuarine protected area that is ecologically at risk, large-scale measures are required to control the sources of contamination.

Variation in PAH patterns in road runoff

Twelve particle-bound polycyclic aromatic hydrocarbons (PAHs) were measured in the first flush regime of road runoff during nine events in Winterthur in Switzerland. The total PAH contents ranged from 17 to 62 μg/g. The PAH patterns measured at different time intervals during the first flush periods were very similar within each event irrespective of variation in suspended solids (SS) concentration within the first flush regime. However, the PAH patterns were different from event to event. This indicates that the environment plays an important role in PAH accumulation in SS. A toxicity identification evaluation approach using a toxicity equivalency factor (TEF) was applied to compare toxicities in the different events. The TEFs were found to be between 8 and 33 μg TEQ g(-1) (TEQ: toxic equivalent concentration). In some cases, two events having similar total PAH contents showed two fold toxicity differences.

Extraction of bioavailable contaminants from marine sediments: An approach to reducing toxicity using adsorbent parcels

This paper demonstrates an approach to reducing acute toxicity in marine sediments using adsorbent parcels. Acute toxicity tests were carried using the marine amphipod Corophium volutator. Marine sediments were spiked with two know contaminants tributyltin and naphthalene and then treated with adsorbent parcels containing either amberlite XAD4 or activated carbon. Results showed that both types of adsorbent parcels were effective in reducing acute toxicity, not only within spiked sediments containing naphthalene and/or tributyltin, but also in an environmental field samples form an expected contaminated site. Adsorbent parcels such as these could provide a practical approach to remediate areas of contaminated sediment within marine environments. Furthermore adsorbents can be used as an identification tool for problematic contaminants using a toxicity identification evaluation approach.

Reproductive Steroid Responses in Fish Exposed to Pulp Mill Condensates: An Investigation of Cause Case Study

Abstract An investigation of cause (IOC) approach integrating artificial stream exposures and laboratory bioassays has been used to identify waste stream sources of contaminants at the Irving Pulp & Paper Ltd. mill, in Saint John, New Brunswick, Canada. Chemical recovery condensates have shown the greatest potential for reducing circulating steroids in mummichog (Fundulus heteroclitus), an endemic fish species. A solid phase extraction (SPE) technique was developed to isolate hormonally active substances from the condensates, and a toxicity identification evaluation approach was used to gain a better understanding of the chemical characteristics of the active substances. Extracts were fractionated by high performance liquid chromatography (HPLC) and the fractions were used in a seven-day bioassay. Dose-response experiments indicated that steroid reductions in male mummichog were observed consistently after a 4% (vol/vol) exposure. At 4% (vol/vol), however, steroid reductions were not observed in fractions of the active SPE extract generated by HPLC. Some fractions actually induced increases in plasma testosterone. Recent work has focused on understanding what methodologies must be used to handle the semivolatile condensates to ensure 100% chemical recovery and retention of biological activity. Results are summarized in the context of developing an industry-wide IOC framework.

A toxicity identification evaluation approach to studying estrogenic substances in hog manure and agricultural runoff.

Spreading liquid manure on agricultural fields is a routine way of disposing of animal manure and optimizing the use of nutrients for crops. Limited studies suggest that these wastes may contain a variety of endocrine-disrupting compounds (EDCs) that may be released into aquatic environments through runoff. The purpose of this study was to apply a toxicity identification and evaluation approach to isolate and identify estrogenic compounds in hog manure. A recombinant yeast estrogen screen bioassay was used to detect estrogenicity of high-performance liquid chromatography--separated hog manure fractions. Further analytical analyses of the fractions and comparison to authentic standards resulted in the identification of the endogenous estrogens 17 beta-estradiol (E2) and estrone, and the phytoestrogen metabolite, equol. High levels of equol (6.9-16.6 ppm) were found to be present in manure that was stored for several months. The endocrine-disrupting potential of equol was characterized further by using fish hormone estrogen receptor (ER), sex hormone binding protein (SSBP), and goldfish androgen receptor (AR) radioligand binding assays. Equol was found to be approximately 1,000- and 200-fold less potent that E2 in competing for binding sites of the SSBP and ER, respectively. Equol's potency was 2,200-fold less than testosterone for the AR. Additional studies confirmed the presence of compounds with estrogenic activity in tile drain water after application of hog manure to an agriculture field. In this case, the contribution of equol to the total estrogenicity of the tile drain water was minimal relative to that of natural estrogens. Overall, this study indicates that further work is warranted to assess the impact that EDCs that originate from agricultural runoff may have on the ecology or physiology of exposed biota.

Identification and treatment of a waste stream at a bleached‐kraft pulp mill that depresses a sex steroid in the mummichog (Fundulus heteroclitus)

AbstractChanges to indicators of reproductive performance have been documented in fish exposed to some bleached kraft pulp mill effluents (BKPMEs). However, responses are not consistent across mill types or processes. It is not clear where the sources of the effects are within mills, what the causative compounds are, or what process changes are effective to remove these sources. Our previous studies suggested that condensates were a source of compounds that reduced plasma testosterone in the mummichog (Fundulus heteroclitus). Results also suggested that reverse osmosis (RO) treatment of condensates removed this source. The objective of this study was to use a toxicity identification evaluation approach and expose mummichog to various waste streams in the laboratory to identify the effluent source that depressed plasma testosterone in the mummichog and the effects of RO treatment. In 7‐ and 21‐d exposures, mummichog were exposed to dilutions of RO feed condensate, RO permeate, combined mill effluent (CME), and final effluent. Results confirmed that condensates depressed plasma testosterone in mummichog. Chemical characterization of the condensate indicated that plant phytosterols were likely not the responsible compounds. Results also confirmed that RO treatment removed the potential of the condensates to depress plasma testosterone in mummichog at environmentally relevant concentrations of final mill effluent (1%).

Identification and treatment of a waste stream at a bleached-kraft pulp mill that depresses a sex steroid in the mummichog (Fundulus heteroclitus).

Changes to indicators of reproductive performance have been documented in fish exposed to some bleached kraft pulp mill effluents (BKPMEs). However, responses are not consistent across mill types or processes. It is not clear where the sources of the effects are within mills, what the causative compounds are, or what process changes are effective to remove these sources. Our previous studies suggested that condensates were a source of compounds that reduced plasma testosterone in the mummichog (Fundulus heteroclitus). Results also suggested that reverse osmosis (RO) treatment of condensates removed this source. The objective of this study was to use a toxicity identification evaluation approach and expose mummichog to various waste streams in the laboratory to identify the effluent source that depressed plasma testosterone in the mummichog and the effects of RO treatment. In 7- and 21-d exposures, mummichog were exposed to dilutions of RO feed condensate, RO permeate, combined mill effluent (CME), and final effluent. Results confirmed that condensates depressed plasma testosterone in mummichog. Chemical characterization of the condensate indicated that plant phytosterols were likely not the responsible compounds. Results also confirmed that RO treatment removed the potential of the condensates to depress plasma testosterone in mummichog at environmentally relevant concentrations of final mill effluent (1%).

Identification and confirmation of ammonia toxicity in contaminated sediments using a modified toxicity identification evaluation approach

Toxicity identification of sediment pore waters from four sites in the Upper Scheldt (Belgium) was assessed using a simplified and discriminative toxicity identification evaluation procedure. The samples from all locations exhibited acute toxicity toward the freshwater crustacean Thamnocephalus platyurus. Toxicity was removed or considerably reduced by the cation exchange resins and air stripping at pH 11. In addition, the toxicity of the pore waters was found to be highly pH dependent. Increased toxicity was observed at higher pH levels, whereas reduced toxicity was found at lower pH levels. Based on these results, ammonia was suggested as the main toxic agent. The presence of ammonia concentrations exceeding the 24-h median lethal concentration and comparison of the toxicity characterization profiles of the pore waters with those of the suspected toxicant supported this hypothesis. Furthermore, a significant positive correlation between the observed toxicity of the pore waters and the expected toxicity (due to the presence of the suspected toxicant) confirmed ammonia as the true toxic agent. Finally, the ratio between the expected ammonia toxicity and the observed toxicity from the characterization tests was approx. 1, meaning that all or most of the observed toxicity was caused by the presence of one toxicant (i.e., ammonia). The developed toxicity identification evaluation procedure is suggested as a usefull tool for the identification and confirmation of toxicants in contaminated sediments.