Nitrapyrin

Short-term toxicity to fish

Description of key information

FRESHWATER FISH

LC50  = 9.0 mg/L (fathead minnow), EPA OPPTS 850.1075, Fournier (2014)

LC50  = 8.8 mg/L (rainbow trout), EPA OPPTS 850.1075, Fournier (2014)

LC50 = 9.1 mg/L (rainbow trout); LC50 = 7.9 mg/L (bluegill), EPA publication method, McCarty (1978)

Geometric mean LC50 (based on the aforementioned LC50 values = 8.69 mg/L )

LC50  = 4.0 mg/L (rainbow trout), EPA OPP 72-1, Weinberg et al. (1991) - incomplete dissolution of test material in test solutions

LC50  = 3.4 mg/L (bluegill), EPA OPP 72-1, Weinberg et al. (1991) - incomplete dissolution of test material in test solutions

SALTWATER FISH

LC50 = 4.28 mg/L (tidewater silverside), method comparable to EPA OPP 72-1, Ward (1990)

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

8.69 mg/L

Marine water fish

Marine water fish

Effect concentration:

4.28 mg/L

Additional information

Seven data sources, reporting the short term toxicity of the substance to fish, are available. Six of the pieces of data are considered together in a weight of evidence approach. Mayer & Ellersieck (1986) lacks sufficient detail and is included as supporting information only.

 

Fournier (2014) reported the findings from two studies. Both studies were conducted under GLP conditions and followed the methods outlined in the standardised guideline EPA OPPTS 850.1075.

In the first study, Pimephales promelas (fathead minnow) were used and in the second study, Oncorhynchus mykiss (rainbow trout) were used. In each study the fish were exposed to nominal concentrations of test material of 0.94, 1.9, 3.8, 7.5 or 15 mg/L in two replicate flasks under semi-static renewal conditions. Duplicate flasks were included for the solvent control (DMF) and dilution water control (well water). All aquaria were examined after 0, 6, 24, 48, 72 and 96 hours of exposure for mortalities and adverse effects.

In the study with fathead minnow, mortality of 80 % was observed among fish exposed to the 12 mg/L treatment level following 72 hours of exposure. Following 96 hours of exposure, no additional mortality was observed among fish exposed to the remaining treatment levels tested. After 96 hours of exposure, the surviving fish in the 12 mg/L treatment level were observed to be on the bottom of the aquaria. One fish in the 2.8 mg/L treatment level was observed to be dark in pigmentation and lethargic while fish in the 5.5 mg/L treatment level were observed to be dark in pigmentation and either had a partial loss of equilibrium or were lethargic. No mortality or adverse effects were observed among fish in the dilution water control or solvent control. Therefore, under the conditions of the test, and based on mean measured concentrations tested, the 96-hour LC50 was determined to be 9.0 mg/L, with 95 % confidence limits of 8.0 to 10 mg/L. The No Observed Effect Concentration (NOEC) was determined to be 1.4 mg/L.

In the study with rainbow trout 100 % mortality was observed in the 13 mg/L treatment level after 24 hours. Following 96 hours of exposure, 10% mortality was observed in the 6.4 mg/L treatment level; all surviving fish exposed to the 6.4 mg/L treatment level were observed to be dark in pigmentation and either had a partial loss of equilibrium or were found on the bottom of the tank. Two fish exposed to the 3.3 mg/L treatment level were observed to be dark in pigmentation. No mortality was observed among fish in the control, solvent control or the remaining treatment levels tested (0.79, 1.7, and 3.3 mg/L). Under the conditions of the study, and based on mean measured concentrations tested, the 96-hour LC50 was determined to be 8.8 mg/L, with 95 % confidence limits of 7.1 to 10 mg/L. The No Observed Effect Concentration (NOEC) was determined to be 1.7 mg/L.

In a study reported by Weinberg et al. (1991), the acute toxicity of the test material to the freshwater fish Oncorhynchus mykiss Walbaum (rainbow trout), was investigated under GLP conditions and in accordance with the standardised guideline EPA OPP 72-1. During the study ten rainbow trout were exposed to each treatment level: 0.9, 1.0, 1.6, 2.9, 4.9, and 10.8 mg/L (active ingredient), an acetone control, and a laboratory water control, under static conditions. The test vessels were observed daily for and sub-lethal effects.

All fish died at the highest test concentration (10.8 mg/L). Sub-lethal effects, such as lethargy, surface swimming, erratic movement, and loss of equilibrium were not noted below the 1.6 mg/L dose levels. Under the conditions of the study the 96 hour LC50 was determined to be 4.0 mg/L (a.i.) with a 95 % confidence interval of 3.1-5.4 mg/L. The 96 hour NOEC was 1.0 mg/L (a.i.).

In a study reported by Weinberg et al (1991), the acute toxicity of the test material to the freshwater fish Lepomis macrochirus (bluegill), was investigated under GLP conditions and in accordance with the standardised guideline EPA OPP 72-1. During the study ten bluegill were exposed to each treatment level: 1.3, 1.5, 2.3, 4.0, 5.5 and 9.3 mg/L (active ingredient), a DMF control, and a laboratory water control, under flow-through conditions. The test vessels were observed daily for and sub-lethal effects. All of the fish exposed to the highest test concentrations of 5.5 mg a.i./L and 9.3 mg a.i./L had died by the 96 hour observation. The 96-hour mortality threshold concentration was 2.3 mg/L. Sub-lethal effects, such as lethargy, surface swimming, and loss of equilibrium, were not noted below the 2.3 mg/L dose levels. Under the conditions of the study the 96 hour LC50 was determined to be 3.4 mg/L (a.i.) with a 95% confidence interval of 2.3 - 5.5 mg/L. The 96 hour NOEC was 1.5 mg/L (a.i.).

 

In a study reported by Ward (1990), the acute toxicity of the test material to the saltwater fish Menidia beryllina (tidewater silverside), was investigated under GLP conditions and following methods comparable to those outlined in the standardised guideline EPA OPP 72-1. During the study twenty silversides were exposed to each treatment level, 1.26, 2.24, 3.15, 5.82 and 10.4 mg/L, a DMF control, and a laboratory water control, under flow-through conditions. The test vessels were observed daily for and sub-lethal effects. Mortality of silversides exposed for 96 hours to test material ranged from 0 percent at mean measured test concentrations of 2.24 and 3.15 mg/L to 100 percent at test concentrations ≥ 5.82 mg/L; 10 percent mortality occurred in 1.26 mg/L. There was no mortality in the dilution water and solvent controls. After 96 hours of exposure, one fish in 2.24 and five fish in 3.15 mg/L were noticeably darker in colour than control fish. Under the conditions of the study the 96 hour LC50 was determined to be 4.28 mg/L with a 95% confidence interval of 3.15 - 5.82 mg/L. The 96 hour NOEC was not determined based on the presence of mortality or observations of darkly pigmented fish in all test concentrations.

 

In a study reported by McCarty (1978) the acute toxicity of the test material to Salmo gairdneri (rainbow trout) and Lepomis macrochirus (bluegill), was investigated following test methods described in the EPA publication "Methods for Acute Toxicity Tests with Fish, Macroinvertebrates, and Amphibians". Tests were conducted by placing 8 L of dechlorinated Lake Huron water in each vessel, a round glass aquarium measuring 22 cm deep with a 24.5 cm diameter, adding the fish, then aerating. If no deaths occurred in 24 hours, aeration was stopped and the test solution added with 2 L of water for mixing, making a total of 10 L. Any vessel containing dead fish was cleaned, reset, and observed for another 24 hours prior to test material addition. Constant temperature water troughs maintained the temperature at 12 ± 1°C, and 22 ± 1 °C, respectively. Ten fish were exposed to each concentration of the test material. Observations were made and recorded, and dead fish removed at the same time for four days (96 hours). Death was used for the effect criterion. Under the conditions of the study the 96 hour LC50 was determined to be 9.1 (8.9 - 9.4) mg/L for rainbow trout and 7.9 (7.4 - 8.5) mg/L for bluegills.

 

Furthermore, secondary data (Mayer & Ellersieck (1986)) are available on the acute toxicity of the test material to rainbow trout, fathead minnow and channel catfish. The LC50 for rainbow trout exposed to test water of hardness 44 mg/L, under static conditions, was reported to be 7.5 mg/L. The LC50 for rainbow trout exposed to test water of hardness 272 mg/L, under static conditions, was reported to be 6.5 mg/L. The LC50 for fathead minnow exposed to test water of hardness 44 mg/L, under static conditions, was reported to be 10.2 mg/L. The LC50 for fathead minnow exposed to test water of hardness 272 mg/L, under static conditions, was reported to be 9.6 mg/L. The LC50 for channel catfish exposed to test water of hardness 44 mg/L, under static conditions, was reported to be 5.8 mg/L. No further information is provided on methods followed or results obtained.

Findings from the majority of the studies are in good agreement with each other. Studies reported by Weinberg, which had lower reported LC50 values also reported incomplete dissolution of the test material in the test solutions.