Registration Dossier

Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
June 2, 1993
Reliability:
2 (reliable with restrictions)

Data source

Reference
Reference Type:
publication
Title:
The Toxicity of Hexahydro-1,3,5-Trinitro-1,3,5-Triazine
Author:
Dennis T. Burton, Steven D. Turley and Gregory T. Peters
Year:
1993
Bibliographic source:
Water, Air and Soil Pollution
Report Date:
1993

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
EPA OTS 797.1050 (Algal Toxicity, Tiers I and II)
Deviations:
no
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent

Sampling and analysis

Analytical monitoring:
yes

Test organisms

Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
A green alga (S. Capricornutum) starter culture was obtained from the culture collection at the University of North Texas, Denton, TX. Stock algal cultures were reared in 2.5 L Pyrex culture flasks containing 1 L of sterilized double strength 'AAP' algal assay medium, with sufficient P added to achieve a 20:1 N:P ratio as described in Miller et al. (1978). Cultures were maintained in a constant temperature incubator under constant cool-white fluorescent lights at a temperature of 20 °C on a shaker table oscillating at 100 rpm.

Results and discussion

Effect concentrationsopen allclose all
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
36.7 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
cell number
Remarks on result:
other: A maximum reduction of 38% in cell density occured after a 96-h exposure to 36.7 mg/L ; thus, an EC50 could not be determined.
Dose descriptor:
LOEC
Effect conc.:
4.8 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
cell number
Dose descriptor:
NOEC
Effect conc.:
0.5 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
cell number
Details on results:
The toxicity data for S. capricornutum exposed to RDX are given in the table (see below). A maximum reduction of 38% in cell density occured after a 96-h exposure to 36.7 mg/L; thus, an EC50 could not be determined. The maximum reduction in cell density occured at the solubility limit of RDX in algal assay media at the assay temperature of 20 °C. The saturation concentration of 36.7 mg/L obtained in this study in algal assay media is slightly lower than the values reported in the literature for aqueous solutions.

Any other information on results incl. tables

 Conc. (mg/L)  Rep              Mean cell density
   0 -h  24 -h  48 -h  72 -h  96 -h
 control

1

2

3

10 69990939568  162561339514571  265975019563989 83213220883261008  26950710449281186997
 0.47

1

2

3

847795238848 116561341912037  916884874447064  220040215171237661  98950010037531033027 
 4.81

1

2

3

106001031710203  132691532816043  566514622446181  259448176947160723  901000802913787680 
 7.95

1

2

3

102271053110219  228961721613389  464755959549837  215797270280232611  9281471017213915880 
 13.02

1

2

3

10707114939643  163391273613104  560295390949304  229739252917232821   895780847627840587
 21.80

1

2

3

121441116310651  120241509117109  558774888846363  189949181339204784  670067683847769940 
 36.69

1

2

3

13624106939520  147091566414197  522514915248056  214413187171183629  767220638587662040 

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
RDX was not acutely toxic to the green alga Selenastrum capricornutum when tested at the solubility limit of the compound in algal assay media. A maximum reduction of 38% in cell density occured after a 96-h exposure to 36.7 mg/L ; thus, an EC50 could not be determined.
The lowest-observed-effect concentration (LOEC) and no-observed-effect concentration (NOEC) for the green alga were 4.8 and 0.5 mg/L, respectively, when chronic endpoints were used to analyze the data. A comparison of the data in this study with RDX toxicity data from the literature for the diatom Navicula pelliculosa, and the blue-green algae (cyanobacteria) Microcystis aeruginosa and Anabeana flos-aquae shows that S. capricornutum is the most sensitive to RDX.