Tris(methylphenyl) phosphate

Endpoint summary

Additional information

Summary of results:

Fish

 

Acute

Studies are presented for a variety of species as follows:

Rainbow trout: LC50 (96- h): 0.6 mg/L test mat. (nominal) (K2)

Fathead minnow:LC50 (96- h): 44.8 mg/L test mat. (nominal) (K2)

Salmo gairdneri (new name: Oncorhynchus mykiss):LC50 (96- h): 0.6 mg/L test mat. (nominal) & 0.75 mg/L test mat. (nominal) (K2)

Pimephales promelas:LC50 (96- h): > 100 mg/L test mat. (nominal) (K2)

Lepomis macrochirus:LC50 (96- h): 7000 ppm test mat. (nominal) (K4)

Menidia beryllina:LC50 (96- h): 8700 ppm test mat. (nominal) (K4)

 

The results demonstrate that toxicity is prevalent in certain species, but not others. However, this may be due to differences in the methodology and testing procedures utilised.

As it is known that the phosphates as a group demonstrate toxicity to aquatic organisms, the LC50 value for hazard assessment is taken as 0.6 mg/l.. The risk phrase "Very toxic to aquatic organisms" is applicable.

 

Chronic

Review of the data set available for the phosphates as a group indicates that these do pose hazardous effects to fish in chronic studies. Long-term toxicity of tris(methylphenyl)phosphate was assessed in an early-life stage toxicity test with Jordanella floridae. The experimental procedure was based on the dutch national standard method NEN 6504: Acute toxicity test with Poecilia reticulata. The early-life stages of fish are exposed for 28 days to 5 concentrations of the test substance dissolved in water, first under static conditions, and after hatching under semi-static conditions. The test begun by placing fertilised eggs in the test chambers and is continued at least until all the fish are free-feeding. Lethal effects and quantitative growth (weight and length) as sub-lethal effects are assessed and compared with control values to determine the no observed effect concentration (NOLC/NOEC). Stability of test substance was monitored during the experiment. All results refer to measured concentration. Embryonic development took place for 5 to 6 days and within one day all fish hatched. It was shown that hatched fish are more sensitive than embryos (eggs). For the endpoint egg development, a NOEC of 1.0 mg/l was obtained. Observation on mortality and sub-lethal effects results in a NOLC and NOEC of 0.01 mg/l. As analytical monitoring was carried out, the results relate to measured concentrations. This toxicity study is classified as acceptable and satisfies generally accepted scientific standards for the early-life stage toxicity test.

3 additional studies are also included. Although limited data is reported within these, the results are considered to support a weight of evidence approach, as these are comparable to other values for long term toxicity to fish in other studies, including those on analogues. 

 

A NOEC for long term fish toxicity is assigned as 0.01 mg/l

 

Daphnia

 

Acute

Three studies are presented for acute toxicity to Daphnia Magna, with the following results:

 

EC50 (48- h): 146 µg/L test mat. (estimated) based on: mortality (and mobility) 

LC50 (48- h): 0.27 mg/L test mat. (nominal) based on: mortality

LC50 (48- h): 0.09 mg/L test mat. (nominal) based on: mortality

 

The results clearly demonstrate that toxicity is prevalent. As it is known that the phosphates as a group demonstrate toxicity to aquatic organisms, the LC50 value for hazard assessment is taken as146 µg/L. The risk phrase "Very toxic to aquatic organisms" is applicable.

 

Chronic

 

A study was performed to assess the effects of tris(methylphenyl) phosphate on the reproductive output of parthenogenetic Daphnia magna under semi-static conditions. The study was conducted in accordance with the national standard method NEN 6502 (1980): Determination of the chronic toxicity with Daphnia magna. Young female Daphnia, aged less than 24 hours at the start of the test, were exposed to various concentrations. After a 21d-exposure period, the total number of offspring produced per parent animal at the end of the test was assessed. The reproductive output of the Daphnia exposed to the substance was compared to that of the control in order to determine the No Observed Effect Concentration (NOEC). A NOEC of 0.1 mg/l was obtained, expressed in terms of measured concentrations. This toxicity study is classified as acceptable and satisfies generally accepted scientific standards for the long-term toxicity test.

 

A NOEC for long term daphnia toxicity is assigned as 0. 1 mg/l

 

Algae

 

Two studies are available for inspection as follows;

1) K1 study: Selenastrum capricornutum were exposed to a 2500 µg/L accommodated fraction (WAF) loading rate of tricresyl phosphate (TCP) and evaluated for effects on cell density, area under the growth curve and growth rate. The 72 and 96-hour EL50, based on cell density, biomass and growth rate, was >2500 µg/L. The 72-hour NOAEL for cell density, biomass and growth rate was 2400, >2500 and >2500 µg/L, respectively, based on a calculated EL10 value. The 96 hour NOAEL, based on cell density, biomass and growth rate was 2500 µg/L.

 

2) K1 Study Conducted on 'Reaction mass of bis(methylphenyl) phenyl phosphate and diphenyl tolyl phosphate and tris(methylphenyl) phosphate', Desmodesmus subspicatus was exposed for a period of 72 h to test solutions with concentrations, nominally 0.0122, 0.0243, 0.0486, 0.0972 and 0.194 mg/L. The cell densities were measured at 24 hour intervals. Inhibition of the algal population was measured as reduction in growth rate (index r), relative to control cultures grown under identical conditions. Growth rates were also used to calculate a No Observed Effect Concentration and a Lowest Observed Effect Concentration according to Williams Multiple Sequential t-Test Procedure. The following values were determined: ErC 50: 0.4042 mg/L and ErC 10: 0.016 mg/L. As analytical monitoring was carried out, the results are expressed in terms of geometric mean measured concentrations. Effective concentrations ranged from 65.5-69.1% of nominal values at 0 hours, and from 49.0-52.1% of nominal values at 72 hours, respectively. This toxicity study is classified as acceptable and satisfies the guideline requirements for the acute algae study.

 

No toxicity at the limit of solubility in water was therefore noted in either study, and it is proposed that the substance does not cause algistatic effects at the limit of solubility.

 

Toxicity to microorganisms

 

A laboratory test was carried out with Kronitex TCP to evaluate the effect of the test item on microorganisms by measuring the respiration rate.

The NOEC was determined to be 1000 mg/L.

 

The NOEC for respiration rates was not based on the results of a statistical analysis, but it is biologically justified. The respiration rates were not inhibited and influenced dose dependently in the whole concentration range, and the observed slight inhibition (14.6 %) at the concentration level of 1000 mg/L was evaluated as reflecting the biological variability in the test. The calculated respiration rate, 0.350 (at 1000 mg/L) was below the historical control data range (0.522 +/- 0.069), but the deviation from the control was within +/- 15 %, it can be considered as a biological variability of the test system.