Aquatic Toxicity Testing

SGS routinely conducts Aquatic Toxicity Testing in conjunction with National Pollutant Discharge Elimination System (NPDES) permits. SGS performs both Acute and Chronic testing in accordance with state protocols for municipal and industrial clients. SGS participates in the annual Environmental Protection Agency's DMR-QA study for Whole Effluent Toxicity (WET) by conducting and reporting the results for acute and chronic testing using a reference toxicant for various species.

Acute Testing

Acute testing includes static renewal and non-renewal tests for both invertebrates (Daphnia Magna and Ceriodaphnia Dubia) and vertebrate (Fathead Minnow). The duration of acute testing ranges from 24-hours to 96-hours. Acute testing includes the measurement of survival based on a series of dilutions (i.e. 100%, 50%, 25% 12.5% and 6.25%).

Acute results are reported as an LC50 value. The LC50 measures the lethal concentration as which the waters being tested kills 50% of the testing organisms. SGS routinely reports the Toxicity Units for acute (TUa) value which is equal to 100/LC50. SGS’s team of biologists and technicians are experienced in supporting the client when toxicity is present. This includes conducting Toxicity Identification Evaluations (TIE's) and Toxicity Reduction Evaluations (TRE's).

Chronic Testing

Chronic testing includes static renewal tests for both invertebrates (Ceriodaphnia Dubia) and vertebrate (Fathead Minnow). The duration of chronic testing ranges from 7-days to 21-days. Chronic testing includes the measurement of survival and reproduction for invertebrates and survival and growth for vertebrates based on a series of dilutions (i.e. 100%, 50%, 25% 12.5% and 6.25%).

Chronic results are reported as the No Observed Effect Concentration (NOEC). The NOEC measures the highest concentration at which the test organism shows no adverse effect on the test organism. Some agencies require that the IC25 be reported for chronic tests. IC indicates Inhibition Concentration. IC25 is the level at which the organisms exhibit 25 percent reduction in a biological measurement such as reproduction or growth. It is calculated statistically and used in chronic toxicity testing. SGS routinely reports the Toxicity Units for Chronic (TUc) value which is equal to 100/IC25.