Effects Characterization
Biotic Effects
Key studies of the toxicity of DNOC to organisms in different environmental media are presented in Tables 6 to 9. Studies primarily on the acute toxicity of DNOC to microorganisms, aquatic invertebrates, insects, terrestrial invertebrates and vertebrates were located in the literature. No acute or chronic marine toxicity data were identified.
| Organism | Endpoint1 | Concentration (mg/L) |
Reference |
|---|---|---|---|
| Microorganisms | |||
| Bacterium Pseudomonas putida | Toxic threshold, 16-hour EC3 (growth) | 16 | Bringmann and Kühn, 1980 |
| Cyanobacterium Microcystis aeruginosa | Toxic threshold, 72-hour EC3 (growth) | 0.15 | Bringmann and Kühn, 1978 |
| Green alga Scenedesmus quadricauda | Toxic threshold, 7-day EC3 (growth) | 13 | Bringmann and Kühn, 1980 |
| Green alga Scenedesmus subspicatus | 96-hour EC50 (biomass) 48-hour EC50 (growth rate) |
6 12 |
Sewell et al., 1995a Sewell et al., 1995a |
| Protozoan Entosiphon sulcatum | Toxic threshold, 72-hour EC5 (growth) | 5.4 | Bringmann and Kühn, 1980 |
| Protozoan Chilomonas paramecium | Toxic threshold, 72-hour EC5 (growth) | 5.4 | Bringmann and Kühn, 1981 |
| Protozoan Uronaemia parduczi | Toxic threshold, 72-hour EC5 (growth) | 0.012 | Bringmann and Kühn, 1981 |
| Aquatic plants | |||
| Lemna minor | Specific growth rate, 7-day exposure | 0.32 | Sloof and Canton, 1983 |
| Aquatic invertebrates | |||
| Water flea Daphnia magna | 24-hour LC50 14-day LC50 14-day NOEC (reproduction) 24-hour LC50 24-hour NOEC (mortality) 21-day NOEC (reproduction) |
5.7 1.6 0.6 2.3 1.5 1.3 |
van der Hoeven, 1984 van der Hoeven, 1984 van der Hoeven, 1984 Kühn et al., 1989 Kühn et al., 1989 Kühn et al., 1989 |
| Water flea Daphnia pulex | 48-hour EC50 3-hour LC50 (DNOC sodium salt) |
0.145 3.5 |
Mayer and Ellersieck, 1986 PAN, 2004 |
| Scud Gammarus fasciatus | 96-hour LC50 | 0.11 | Mayer and Ellersieck, 1986 |
| Insects | |||
| Pteronarcys californica | 96-hour LC50 | 0.32 | Mayer and Ellersieck, 1986 |
| Vertebrates (fish) | |||
| Bluegill Lepomis macrochirus | 96-hour LC50 96-hour LC50 |
0.95 0.36 |
Sewell et al., 1995b Mayer and Ellersieck, 1986 |
| Rainbow trout Oncorhynchus mykiss | 96-hour LC50 96-hour NOEC 96-hour LC50 |
0.45 0.32 0.066 |
Sewell et al., 1995c Sewell et al., 1995c Mayer and Ellersieck, 1986 |
| Atlantic salmon Salmo salar | 96-hour LC50 | 0.20 | Zitko et al., 1976 |
| Bluegill Lepomis macrochirus | 96-hour LC50 | 0.23 | Buccafusco et al., 1981 |
| Goldfish Carassius auratus | 48-hour LC50 (DNOC sodium salt) | 0.45 | PAN, 2004 |
| Common carp Cyprinus carpio | 13-day NOEC (pH 6.9-9.0) 13-day NOEC (pH 7.8) 13-day NOEC (pH 9.0) |
≤0.25 0.5-1.0 no effect |
Ghillebaert et al., 1995 |
| Common mirror-coloured carp Cyprinus carpio | 48-hour LC50 (DNOC sodium salt) | 0.17 | PAN, 2004 |
| Medaka high eyes Oryzias latipes | 48-hour LC50 (DNOC sodium salt) | 0.20 | PAN, 2004 |
1 EC = effective concentration; LC50 = median lethal concentration; NOEC = No-Observed-Effect Concentration.
| Organism | Endpoint1 | Concentration (mg/L) |
Reference |
|---|---|---|---|
| Tobacco Nicotiana sylvestris | ED50 | 0.466 | Strube et al., 1991 |
1 ED50 = median effective dose.
| Organism | Endpoint | Concentration | Reference |
|---|---|---|---|
| Earthworm Eisenia fetida | 7-day LC50 14-day LC50 14-day NOEC |
17 mg DNOC/kg of soil 15 mg DNOC/kg of soil 10 mg DNOC/kg of soil |
van der Hoeven, 1992 |
| Honey bees Apis mellifera | LD50 (oral) LD50 (contact) |
2.04 ± 0.25 µg DNOC/bee 406 ± 27µg DNOC/bee |
Beran and Neururer, 1955 |
| Organism | Endpoint | Concentration (mg/kg-bw) |
Reference |
|---|---|---|---|
| Japanese quail Coturnix japonica | 24-hour LD50 | 14.8 (95% CI1 13-17) | Dickhaus and Heisler, 1980 |
| Japanese quail Coturnix japonica | 8-day LC50 | 106 | Til and Kengen, 1980 |
| Pheasants | LD50 | 8.4 | Janda, 1970 |
| Partridges | LD50 | 8.3 | Janda, 1970 |
| Rat | 90-day LOEL | 2.5 (per day) | Den Tonkelaar et al., 1983 |
1 CI = confidence interval.
The most sensitive aquatic vertebrates reported in the literature are rainbow trout (Mayer and Ellersieck, 1986; Sewell et al., 1995c). The authors reported LC50 values of 0.066 and 0.45 mg/L, respectively. The 96-hour LC50 study reported by Sewell et al. (1995c) is an unpublished study; however, it was cited in a peer-reviewed report (IPCS, 2000). Atlantic salmon and bluegill are also sensitive, with 96-hour LC50 values of 0.20 mg/L and 0.23 mg/L, respectively (Zitko et al., 1976; Buccafusco et al., 1981).
The effect of DNOC on terrestrial vertebrates (mink and otter) (Critical Toxicity Value [CTV] for wildlife) was calculated using the repeated mammalian (rat) oral dose toxicity data provided for the substance (2.5 mg/kg-bw per day for a 90-day rat dietary exposure study, Lowest-Observed-Effect Level [LOEL]) (Den Tonkelaar et al., 1983). The CTVwildlife is calculated by taking the chronic value (geometric mean of the No-Observed-Effect Level [NOEL] and LOEL) from the rat study and correcting it for body weight of a predictive sentinel species (Sample et al., 1996). In this case, the predictive sentinel species are the piscivorous mammals mink and river otter. The CTVwildlife is thus calculated as:
CTVwildlife = ChVts · (BWts/BWpss)
where,
ChVts = chronic value for test species (geometric mean of LOEL [2.5 mg/kg-bw per day] and NOEL [0.25 mg/kg-bw per day] = 0.8 mg/kg-bw per day)
BWts = mean body weight of test species (0.35 kg)
BWpss = body weight of predictive sentinel species (0.807 kg for mink; 6.01 kg for otter) (Martin, 2004).
Therefore, CTVwildlife = 0.8 × (0.35/0.807) = 0.35 for mink and 0.8 × (0.35/6.01) = 0.047 for otter.
The ENEVwildlife is calculated from the CTVwildlife as follows:
ENEVwildlife = CTVwildlife/AF
where:
ENEVwildlife = wildlife Estimated No-Effects Value (mg/kg-bw per day)
AF = application factor (interspecies variation, laboratory to field extrapolation) (10).
Therefore, the ENEVmink is 0.035 mg/kg-bw per day, and the ENEVotter is 0.0047 mg/kg-bw per day.
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