1,6,7,8,9,14,15,16,17,17,18,18-dodecachloropentacyclo[12.2.1.16,9.02,13.05,10]octadeca-7,15-diene

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to microorganisms, other

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

2014

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Although not a standard OECD method the suitability of the method is well documented in peer-reviewed scientific literature (Ma, X.Y., Wang, X.C., Ngo, H.H., Guo, W.S., Wu, M.N., Wang, N., 2014. Bioassay based luminescent bacteria: interferences, improvements, and applications. Sci. Total Environ. 468 – 469, 1 – 11). Thus, the results are considered reliable with restrictions.

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

other: Microtox assay system

Principles of method if other than guideline:

The Microtox assay system has been recognized to be one of the most rapid and cost-effective methods, which is based on the measurement of the reduction in light emission of luminescent bacteria exposed to a toxic substance (see Bulich, A.A., 1979. Use of Luminescent Bacteria for Determining Toxicity in Aquatic
Environments. American Society for Testing and Materials, Philadelphia, PA, USA. pp. 98–106)

GLP compliance:

not specified

Remarks:

not indicated in the publication

Analytical monitoring:

not specified

Vehicle:

yes

Details on test solutions:

The assay was carried out by adding 2 mL test medium and 10 µL bacterial suspension to a glass tube. The medium was thoroughly mixed and the light unit was recorded by a DXY-3 biological toxicity detector (Nanjing Kuake, China) after 15 min incubation at 22 ± 1 °C. The concentration gradient of DP is 0.591, 2.95, 14.8, 73.8, 369 µg/L, which were diluted by distilled water from DP stock solution accordingly (with the highest final concentration of DMSO 0.1% in 369 µg/L). Relative luminosities (RL) were used to evaluate the effects of DP.
RL = Lt/Lc * 100%
where Lc is luminescence of bacteria exposed to the blank sample, Lt is luminescence of bacteria exposed to the DP samples.

Test organisms (species):

other: lyophilized T3 luminous bacteria

Details on inoculum:

Bioassay with luminous bacterium
The lyophilized T3 luminous bacterium was purchased from Institute of Soil Science, Chinese Academy of Sciences (Nanjing, China). The suspension was prepared according to the assay procedure of GB/T 15441-1995. Briefly, 0.5 g freeze-dried bacteria was revived in 0.5 mL chilled 2% NaCl at 4 °C for 20 – 30 min before testing.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

15 min

Hardness:

not reported

Test temperature:

22 ±1 °C

pH:

not reported

Dissolved oxygen:

not reported

Salinity:

not reported

Nominal and measured concentrations:

nominal concentrations of 0.591, 2.95, 14.8, 73.8, 369 µg DP/L

Reference substance (positive control):

no

Duration:

15 min

Dose descriptor:

NOEC

Effect conc.:

>= 369 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: luminescence

Remarks on result:

other: no effects observed at highest tested concentration

Details on results:

In this assay, the EC 50 values could not be calculated because the luminosities did not decrease with increasing concentrations of DP. Graphical analysis shows the luminosities of luminous bacteria with respect to time following three different treatment protocols (Control, 0.1% DMSO and highest DP concentration used in the experiment, 369 µg/L). The luminosities were relatively stable with respect to time. In addition, the results showed there was no significant difference (p > 0.05) among the different treatment groups. It was seen that the relative light units of luminous bacteria after exposure to different concentrations of DP fluctuate around 100%, suggesting that there is no acute toxicity to luminous bacteria under the studied DP concentrations.

Results with reference substance (positive control):

none applied

Reported statistics and error estimates:

Results were analyzed by SPSS 18.0 software (SPSS Inc.). Statistical differences of biological parameters between DP-treated groups and control group were evaluated using one-way ANOVA test. A probability value < 0.05 (p < 0.05) was accepted as significance.

It is known that the light emission of luminous bacteria is related to cellular metabolism, therefore the light intensity can reflect the metabolic status of the bacteria. When exposed to the toxicant, the luciferase of the bacteria could be inhibited, and the light intensity decreased rapidly (Ma, X.Y., Wang, X.C., Ngo, H.H., Guo, W.S., Wu, M.N., Wang, N., 2014. Bioassay based luminescent bacteria: interferences, improvements, and applications. Sci. Total Environ. 468 – 469, 1 – 11.). This rapid, sensitive and cost-effective assay was used in this study to evaluate the acute toxicity of DP on the environment levels by obtaining the EC 50 values.

Validity criteria fulfilled:

yes

Conclusions:

No acute toxicity to luminuous bacteria up to 369 µg DP/L (highest tested concentration) was observed.

Executive summary:

In this study, luminous bacteria were chosen as testing organisms to investigate the acute toxicity of DP. The concentration gradient of DP used in this study was chosen based on its environmental levels (experiments of luminous bacteria: 0.591, 2.95, 14.8, 73.8, 369 µg/L). For luminous bacteria, the relative luminosities were around 100% in treated groups, which suggested that there is no acute toxicity to luminous bacteria under the studied DP concentrations.

Reference 2

Endpoint:

activated sludge respiration inhibition testing

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

the study does not need to be conducted because the substance is highly insoluble in water, hence indicating that aquatic toxicity is unlikely to occur

Description of key information

The substance is highly insoluble in water and it is not hazardous. No OECD 209 study is available. However, in a bioassay with luminous bacterium, no toxicity was observed up to the highest tested concentration of 369 µg DP/L.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

369 µg/L

Additional information

In a bioassay with luminous bacteria as testing organisms the acute toxicity of DP was investigated. The concentration gradient of DP used in this study was chosen based on its environmental levels (experiments of luminous bacteria: 0.591, 2.95, 14.8, 73.8, 369 µg/L). For luminous bacteria, the relative luminosities were around 100% in treated groups, which suggested that there is no acute toxicity to luminous bacteria under the studied DP concentrations.