reaction mass of 2,2,4,6,6-pentamethylheptane-4-thiol, 2,3,4,6,6-pentamethylheptane-3-thiol , 2,4,4,6,6-pentamethylheptane-2-thiol, 2,3,4,6,6-pentamethylheptane-2-thiol

Bioaccumulation: aquatic / sediment

Administrative data

Endpoint:

bioaccumulation in aquatic species: fish

Type of information:

experimental study

Adequacy of study:

other information

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP - Guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2009

Report date:

2009

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 305 (Bioconcentration: Flow-through Fish Test)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

2,2,4,6,6-pentamethylheptane-4-thiol

EC Number:

296-714-7

EC Name:

2,2,4,6,6-pentamethylheptane-4-thiol

Cas Number:

93002-38-1

Molecular formula:

C12H26S

IUPAC Name:

2,2,4,6,6-pentamethylheptane-4-thiol

Details on test material:

- Name of test material (as cited in study report): tert.-Dodecylmercaptan
- CAS-No as cited in study report: 25103-58-6 (tert. dodecanethiol), but the test material was material as defined in section 1 (CAS 93002-38-1). Therefore the new CAS number 93002-38 was assigned
- Analytical purity: not specified
- Impurities (identity and concentrations): not specified
- Source: Lanxess Deutschland GmbH (Elatomers, remark: Bayer Variante)
- Batch No.: RL71102100

Sampling and analysis

Details on sampling:

- On day ten of the uptake phase, 4 fish for the control and 4 fish each for the test item concentrations were taken from the tanks for analytical purposes.
- After an exposure phase of 10 days the uptake phase ended. Fish were then fed with died free from the test item and reference compound and the depuration phase started. During the depuration phase fish samples for each test item concentration and control were taken on day 2, 6, 8, 11, 16, 18 and 25 after the beginning of the depuration phase. Additionally tissue specific analysis was carried out on day 2 after the beginning of the depuration phase for each test item concentration.

Test organisms

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Details on test organisms:

- Source: Aqua KlöGer (Germany)
- date of birth: April/May 2007
- date supplied: 2007-09-18
- Mortalities during acclimitation period: < 5%
- Medication: none
- Mean standard length and mean wet weight (sample from keeping tanks at the beginning of the study):
4.2 cm (S.D. = 0.19 cm)
885.8 mg (S.D. = 144.3 mg)

Study design

Route of exposure:

feed

Test type:

flow-through

Water / sediment media type:

natural water: freshwater

Total exposure / uptake duration:

10 d

Total depuration duration:

25 d

Test conditions

Test temperature:

20-25 °C (+/- 2°C)

Details on test conditions:

RANGE-FINDING:
An acute toxicity test had shown that the test item was not toxic to Danio rerio in a saturated solution of TDM (nominally: 10.7 g/L with a water solubility of 0.25 mg/L). Based on this information and the recommendations of the guidelines 100 µg/g and 1000 µg/g were selected as test concentrations for the fish dietary study.

- Photoperiod: 16h light:8h dark

Nominal and measured concentrations:

100 µg/g and 1000 µg/g

Reference substance (positive control):

yes

Remarks:

Hexachlorobenzene

Results and discussion

Lipid content

Lipid content 1

Lipid content:

14.9 %

Time point:

start of exposure

Remarks on result:

other: arith. mean value (fish taken from stock population)

Lipid content 2

Lipid content:

8.8 %

Time point:

end of exposure

Remarks on result:

other: arith. mean value (control)

Lipid content 3

Lipid content:

15.8 %

Time point:

end of exposure

Remarks on result:

other: arith. mean value (treatment: 1000µg/g)

Bioaccumulation factor

Bioaccumulation factor 1

Type:

BMF

Value:

0.01 dimensionless

Remarks on result:

other: Conc.in environment / dose:1000 µg/g

Bioaccumulation factor 2

Type:

BCF

Value:

1 615 dimensionless

Remarks on result:

other: range: 1489-1742

Remarks:

Conc.in environment / dose:1000 µg/g

Any other information on results incl. tables

The dietary biomagnification factor (BMF) is calculated as:

BMF = I·a· k_depuration ^-1

a: chemical uptake efficiency

From the data, correcting for fish growth during the test, a BMF of 0.01 was determined for the test item concentration 1000 µg/g. After 8 days of depuration (i.e. feeding unspiked food), no TDM could be determined any more.

At a concentration of 100 µg/g the bioaccumulation was too low to allow quantification.

The growth-corrected half-life is calculated as:

T_1/2 = 0.693·K_depuration^-1

The calculated half life of the test item from the above data was 2.19 days.

Additionally, the average BCF was calculated by the following equation:

BCF = (Ku * T_1/2) / 0.693 and

Ku = (520±40)·W^{-0.32 ± 0.03}

Where:

Ku = the uptake rate constant (L/kg/d)

T_1/2 = growth corrected half-life from dietary bioaccumulation test (days)

W = fish weight (grams wet weight) at the end of uptake/start of depuration

From the BMF data, a BCF of 1615 (1489-1742) was calculated.

The observed BMF was 0.01 and the calculated BCF is below the PBT-criterion (BCF 2000) and clearly below the vPvB-criterion (BCF 5000). Together with the short half-life these data indicate that TDM (tert.-Dodecylmercaptan) is not PBT (persistent, bioaccumulative and toxic) and not vPvB (very persistent and very bioaccumulative).