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Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:
PNEC aqua (freshwater)
PNEC value:
6.2 µg/L
Assessment factor:
10
Extrapolation method:
assessment factor
PNEC freshwater (intermittent releases):
11.2 µg/L

Marine water

Hazard assessment conclusion:
PNEC aqua (marine water)
PNEC value:
0.62 µg/L
Assessment factor:
100
Extrapolation method:
assessment factor

STP

Hazard assessment conclusion:
PNEC STP
PNEC value:
0.21 mg/L
Assessment factor:
10
Extrapolation method:
assessment factor

Sediment (freshwater)

Hazard assessment conclusion:
PNEC sediment (freshwater)
PNEC value:
55 mg/kg sediment dw
Assessment factor:
10
Extrapolation method:
assessment factor

Sediment (marine water)

Hazard assessment conclusion:
PNEC sediment (marine water)
PNEC value:
5.5 mg/kg sediment dw
Assessment factor:
100
Extrapolation method:
assessment factor

Hazard for air

Air

Hazard assessment conclusion:
no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:
PNEC soil
PNEC value:
20 mg/kg soil dw
Assessment factor:
50
Extrapolation method:
assessment factor

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:
PNEC oral
PNEC value:
3.3 mg/kg food
Assessment factor:
300

Additional information

The following background information for the derivation of the PNEC of the differrent environmental compartments is taken from the EU Risk Assessment DODMAC (EU, 2002).

Derivation of the PNEC aquatic

The algae data demonstrate that the difference in the EC50-values of DODMAC and DHTDMAC for laboratory and river water is lower (factor 3 at maximum) than for fish and daphnids. Whereas the toxicity of DODMAC and DHTDMAC seems to be similar for fish and daphnids the sensitivity of algae might be higher for DHTDMAC. However the results for algae described above are not comparable directly as in no reference both substances were tested in parallel under the same conditions. Contradicting results are reported in ECETOC, 1993, forSelenastrum capricornutumin laboratory water, where MTTMAC concentrations increasing from 0% to 4% (added to DHTDMAC) resulted in very similar EC50-values although MTTMAC is reported to be more toxic than DODMAC for algae (Akzo, 1990a,b). Also the chronic toxicity of DHTDMAC in laboratory water forDaphnia magnadoes not increase with increasing concentrations of the more toxic MTTMAC (Akzo, 1991b; cited in ECETOC, 1993). Another point is that MTTMAC adsorbs stronger onto solids than DODMAC[1] so that the bioavailability is relatively lower. Because of the discrepancy of the test results it can only be concluded that the data currently available do not allow firm conclusions to be drawn upon possible different toxicities of DODMAC and DHTDMAC but point to the extreme caution needed for the interpretation of toxicity test results on DHTDMAC. However, when all facts are considered the influence of the water quality seems to be more important than that of MTTMAC.

The above cited test results have a high variability and the interpretation is complicated as the test reports do not always provide all details which would be needed. The difference in different water qualities was most probably caused by adsorption losses and complexation with dissolved colloidal anionic surfactants and humic substances which may reduce bioavailability and thus the effective doses. Although the adsorption onto suspended matter can be modelized for the PEC-calculation (cf. 3.1.1.3), the complexation with anionics can not be calculated. The tests in river water probably reflect both properties (cf. 3.2.1), so that the substance should be assessed with these respective results, having in mind that these results may be due to the special local properties of the water and that it is not possible to simulate the most realistic exposure conditions. The water qualities of the river water tests reflect the range of variability in natural surface waters. Toxicity tests with effluent from a wwtp are not more useful because this matrix increases the complexicity of the problem. It is much more difficult to take such results which are dependent on a combination of two matrices as representative for other environmental situations.

Not the lowest aquatic NOEC in tests with laboratory water of 6 µg/l forSele­nastrum capricornutum,but the lowest NOEC from river water tests (62 µg DHTDMAC/l,Selenastrum capricornutum) is taken into account in order to calculate the predicted no effect concentration (PNEC). This value is supported by other long-term test results with DHTDMAC withMicrocystis aeruginosaandMysidopsis bahiafor which almost the same values are reported.

According to the EU Technical Guidance Document, the value of the assessment factor F is to be determined to 10 for the aquatic compartment, as data from long-term toxicity tests of 3 trophic levels are available and a PNEC is calculated as follows:

 

PNECriver water =62 µg/l / 10= 6.2 µg/l

 

Also other PNEC derivations are possible: In case it would be proven that toxicity ofdodmacfor algae is lower than that of DHTDMAC the lowest river water NOEC would be 0.26 mg/l DODMAC forCeriodaphnia dubia(PNEC = 26 µg/l). Relevant for the risk assess­ment are also DHTDMAC test results with wwpt effluent diluted with river water where the lowest EC20-values were 0.047 and 2.91 mg/l forSelenastrum capricornutum. Similar MATC-values of 0.1 and 3.7 mg/l were obtained forCeriodaphnia dubia. No comparable test was conducted with fish.

A statistical PNEC extrapolation is proposed by van Leeuwen et al., 1992, which gives a maximum tolerable risk level of 50 µg/l based on river water NOECs. However, it is question­able, whether the necessary assumptions for this approach are justified Derivation of the PNEC sediment

For the derivation of the PNECsed only such tests can be used in which the test organisms were exposed to whole sediment spiked with the test substance. Among the above cited tests with sediment organisms four tests are appropriate for the effects assessment of sediment: the studies by Pittinger et al., Conrad et al., Comber/Conrad andBSB. ForChironomus ripariusa NOEC of 876 mg/kg dw was found.Lumbriculus variegatuswas less sensitive to adsorbed DODMAC. A NOEC of about 5000 mg/kg dw was found for this sediment ingesting worm. For the nematodeCaenorhabditis elegansa NOEC of 1350 mg/kg dw was derived. The NOEC found for the oligochaeteTubifex tubifexwas with 1515 mg/kg dw in the same range with the NOECs from the other tests. However, a EC10-value of 550 mg/kg dw could be calculated that is used a basic value for the PNEC derivation.

The other available tests with sediment organisms were conducted in the absence of sediment. As sediment was missing, the bioavailability and toxicity of DODMAC cannot be assessed with these tests. Sediment bioassays have to address all possible routes of exposure (uptake via body surfaces to substances dissolved in the overlying water and in the pore water and to adsorbed substances by direct contact or via ingestion of contaminated sediment particles) However, exposure to bound substance is not considered in tests being conducted in water only.

 

For the derivation of the PNECsed an assessment factor of 10 is applied to the EC10 of 550 mg/kg dw obtained forTubifex tubifex, as long-term tests with species representing three different living and feeding conditions and therefore different exposure pathways are available.

 

Therefore:PNECsed =550 mg/kgdw / 10 =55 mg/kgdw

In accordance to the TGD, the PNECsed can be estimated approximately from the PNECwater with the equilibrium partitioning method. With a PNECriver water of 6.2 µg/l and a partitioning coefficient of 10,000 l/kg (related to dw), the PNECsed would be estimated to 62 mg/kg dw. However, as DODMAC strongly adsorbs to sediments, according to the TGD an additional factor of 10 was applied to take uptake via ingestion of sediment into account. Therefore the PNECsed has to be reduced to 6.2 mg/kg dw. However, the PNECsed derived from sediment tests has a higher priority and is therefore used for the risk assessment.

Derivation of the PNEC STP

Using different safety factors according to the sensitivities of the test systems and the mean effect values the lowest PNEC-values are as follows:

 

Pseudomonas putida     EC50 = 53 mg/l, SF = 100              PNEC = 0.53 mg/l

nitrifying bacteria          EC50= 2.1 mg/l, SF = 10                 PNEC = 0.21 mg/l

secondary effluent          EC50= 4.3 mg/l, SF = 100               PNEC = 0.043 mg/l

 

With all these PNECs it has to be considered that the microorganism toxicity derived in labora­tory water tests has to be handled with care as a high influence of the composition of the waste water (e.g. suspended particles, complexing agents) can be assumed, which is the same phenomenon as in surface water tests. Moreover the lowest PNECmicro-organisms of 0.043 mg/l seems to be unrealistic as it is reported that waste water treatment plants operate at DHTDMAC concentrations of 3 to 8 mg/l (chap. 3.1.2.1). However, it is not documented whether the treatment process would be more effective without this DHTDMAC load in the influent and how less adapted plants might react. Nitrifying bacteria were found to be the most sensitive micro-organisms with the lowest EC50 of 2.1 mg/l on which the risk assessment should be based to ensure that the most sensitive treat­ment process can take place. This results in a PNEC STP = 0.21 mg/l.

Derivation of the PNEC soil

Assuming that two trophic levels are covered with long-term data for plants (Windeatt, 1987) and micro-organisms, an assessment factor of 50 could be applied and the following PNEC is calculated:

                    PNECsoil >/=1000 mg/kg / 50 >/=20 mg/kg

 

With this approach it was accepted that not every test could be validated, but if the terrestrial data are evaluated as a whole this seems to be acceptable in this special case. In case it would turn out that DHTDMAC might be more toxic than DODMAC the PEC/PNEC-ratio for DODMAC should be even saver.

.

Conclusion on classification

Read across from structurally similar Quats DHTDMAC/DODMAC can be applied and the data from DHTDMAC/DODMAC are used for the Classification of DTDMAC according DSD and CLP.

DSD 67/548/EEC

The Environmental classification has to take into account the lowest acute value for aquatic species which is the Algae ErC50 (72h) of 1.17 mg/L (see Section 6.1.5). This study was carried out in river water to ensure a reliable testing of the cationic surfactant DHTDMAC. As a mitigation might have taken place reducing the ecotoxicity, a Mitigation factor of 10 has be applied as a worst case (see CEFIC APAG Aquatic testing approach for Cationic surfactant, REACH Category Approach ‘Primary alkyl amines’). The corrected ErC50 (72h) Algae to be used in Classification is 1.17/10 mg/L = 0.12 mg/L which leads to R50. In addition DHTDMAC is not readily biodegradable (see Section 5.2.1). The measured BCF for DODMAC is 13 L/kg and therefore the bioconcentration potential is very low. The bioaccumulation criteria (BCF >= 100 L/kg) is not fulfilled under DSD 67/548/EEC. Based on these facts and the criteria for classification given in the DSD a R53 has to be assigned as DHTDMAC is not readily biodegradable.

CLP 2008/1272/EEC (2nd ATP

The bioaccumulation criteria under CLP2008/1272/EEC (BCF >= 500 L/kg) is not fulfilled but as DHTDMAC is not readily biodegradable and the lowest chronic NOEC from 3 species is 0.062 mg/L a Chronic category 1 has to be assigned according the CLP criteria (2nd ATP).

Proposed classification according DSD 67/548/EEC:

N, R50/53

Proposed classification according CLP 2008/1272/EEC (2nd ATP)

Acute (short-term) aquatic hazard:

Acute Category 1 with a M factor 1; Hazard statement H400: Very toxic to aquatic life

Chronic (long-term) aquatic hazard:

Chronic Category 1 with a M factor 10; Hazard statement H410: Very toxic to aquatic life with long lasting effects

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