1,2,3-trichloropropane

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.088 mg/L

Assessment factor:

50

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

0.041 mg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.009 mg/L

Assessment factor:

500

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

2.9 mg/L

Assessment factor:

100

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

0.1 mg/kg sediment dw

Assessment factor:

10

Extrapolation method:

equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

0.01 mg/kg sediment dw

Assessment factor:

10

Extrapolation method:

equilibrium partitioning method

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

0.15 mg/kg soil dw

Extrapolation method:

equilibrium partitioning method

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

PNEC oral

PNEC value:

1.8 mg/kg food

Assessment factor:

30

Additional information

PNEC_{aqua freshwater}

Three NOEC values of algae, daphnia, and chronic fish studies are available. For the invertebrates though, the chronic NOEC is higher for daphnia than the EC50 reported for Cerodaphnia. In the absence of better documentation of the testing performed, the study is considered as a valid basis for deriving the PNEC and the chronic Daphnia is therefore not considered for the choice of the assessment factor. Thus the PNEC can be derived on the basis of two long-term results from species representing two trophic levels. An assessment factor (AF) of 50 applies in this case. The lowest concentration of 4.4 mg/L is obtained from fish. Thus the PNEC = 4.4 mg/L ÷ 50 = 0.088 mg/L = 88 µg/L. The AF used above is in accordance with ECHA 2008a, Chapter R.10, Table R.10-4, p 19.

Note that the CICAD document of the WHO states: “A PNEC for surface water was estimated from the lowest EC50 value from tests carried out in closed systems to minimize TCP losses. The 48-h EC₅₀ value for Daphnia magna immobilization (20 mg/L) was used to derive the PNEC, together with an uncertainty factor of 1000: PNEC = 20 mg/L ÷ 1000 = 0.02 mg/L." The data from Ceriodaphnia cf. dubia was neglected in the assessment by the WHO.

PNEC_{aqua marine water}

No data specific to marine organisms is available. The PNEC marine is derived by applying an additional assessment factor of 10 to the PNEC freshwater. PNEC marine = 88 µg/L/10 = 8.8 µg/L.

PNEC_soil and PNEC_sediment

The Equilibrium Partitioning Method was employed for the derivation of the soil and sediment PNEC. This is based on the assignment of TCP to Soil Hazard category 1 because of its low adsorption potential (Walton et al 1992) in conjunction with the reported biodegradation in aerobic soil (Anderson et al 1991) with a half life of 2.7 days and in anaerobic sediment (Peijnenburg et al 1998) with a half life of 7 days and finally the low toxicity to aquatic organisms with EC/LC₅₀ > 1 mg/L for algae, daphnia and fish (ECHA 2008 Guidance on information requirements and chemical safety assessment, Table R.7.11-2, page 131).

The K_oc used was 77 as it is the lowest value in the range from 77 to 94.7. This was considered in application of the precautionary principle because that way lower PNECs result.

Then the PNEC_soil is estimated using equation R.10-5 (ECHA 2008), but the value for RHOsoil, being 1700 kg/m³, taken from ECB 2003, p 44 since the value given in ECHA (2008) is obviously by error the one for RHOsusp being 1150 kg/m³.

PNEC_oral

In accordance with ECHA 2008, Guidance on information requirements and chemical safety assessment Chapter R.10: Characterisation of dose [concentration]-response for environment, Chapter R.10.8.2 the PNECoral can be derived on the basis of mammalian threshold level as no data on effects of TCP to birds are reported. Unfortunately the most relevant 120 day study design failed to reveal a NOAEL because weak effects in males were still present at the lowest concentration. In order to approximate the NOAEL, the obtained LOAEL is divided by 3, so that the threshold level is assigned to 2.7 mg/kg bw per day = NOAELmammal, oral_chr per day obtained from 120 days repeated toxicity data on rats (IUCLID 5 section 7.5.1, Ulland & Rutter 1983).

Critical Body Burden (CBB)

The critical body burden (CBB) concept (McCarty 1986) assumes that chemicals will have a specific effect once a specific internal tissue concentration is reached, regardless of external influences and mode of exposure and the organism or species used. The concept is also referred to as “critical tissue residue” or “internal dose” (e.g. Escher & Hermens 2004). It is considered reasonably well-established for chemicals that act via a narcotic mode of action (Bailey & Thomas 2007). Thompson & Stewart (2003) estimate Chronic CBB of 0.2 to 0.8 mmol/kg, with an approximate indicative range of 0.1-1.0 mmol/kg. Terminology is not always consistent, but “CBB” corresponds to a no effect level from a longer term study (Bailey & Thomas 2007). Thus CBB significantly lower than 0.2  mmol/kg indicate other modes of action than the polar and non-polar narcotic ones.

The CBB is given by the lowest aquatic no observed effect concentration and the experimental bioconcentration facor (MITI 1992). The recent figures on TCP are characterized by the astonishing condition that an EC₅₀ of 4.1 mg/L reported from a significantly sensitive aquatic invertebrate species (Rose et al 1998) is lower than the lowest measured NOEC being 4.4 mg/L in fish (Bernheim at al 2005). However the daphnids (Daphnia magna) acute NOEC value is 8.4 mg/L.

The CBB of TCP is for instance based on the lowest value

• CBB = BCF L/kg ∙ NOEC mg/L = 13 ∙ 4.1 mg/kg = 53.3 mg/kg

The Molecular weight of TCP is =147.432g/mol =147'432 mg/mol and thus the molar CBB is derived by:

• Molar CBB mol/kg = BCF L/kg ∙ NOEC mg/L / MG mg/mol =
  13 L/kg ∙ 4.1 mg/L / 147'432 mg/mol = 0.000'36 mol/kg = 0.36 mmol/kg

It is to conclude that the CBB of TCP gives some evidence for the absence of a specific mode of action, ranging in the typical array for polar and non-polar narcotic modes of action.

References

• Bailey E & Thomas P (2007) Science Dossier Pentachlorobenzene – Sources, environmental fate and risk characterization, Chapter 5.5 Critical Body Burden
• ECHA European Chemicals Agency (2008) Guidance on information requirements and chemical safety assessment Chapter R.7C: Endpoint specific guidance, 235 p; Chapter R.10: Characterisation of dose [concentration]-response for environment, 65 p & Chapter R.16: Environmental Exposure Estimation, 138 p
• ECB European Chemicals Bureau (2003) Technical Guidance Document in support of Commission Directive 93/67/EEC on Risk Assessment for new notified substances, Commission Regulation (EC) No 1488/94 on Risk Assessment for existing substances and Directive 98/8/EC of the European Parliament and of the Council concerning the placing of biocidal products on the market, Part II, 328 p

• EMEA European Medicines Agency (2007) Guideline on Environmental Impact Assessment for Veterinary Medicinal Products in support of the VICH guidelines GL6 AND GL 38 - EMEA/CVMP/ERA/418282/2005-corr, 63 p
• Escher BI & Hermens JLM (2004) Internal exposure: Linking bioavailability to effects - Environ Sci Technol 38:455A-62A.
• McCarty L (1986) The relationship between aquatic toxicity QSARs and bioconcentration for some organic chemicals - Environmental Toxicology and Chemistry 5:1071-80
• Thompson RS & KS Stewart (2003) Critical body burdens: A review of the literature and identification of experimental data requirements Report BL7549, June 2003, Brixham Environmental Laboratory AstraZeneca CEFIC Long range Research Initiative Project.  

Conclusion on classification

In accordance with the Guidance to Regulation (EC) No 1272/2008 on Classification, Labelling and Packaging of substances and mixtures (14 May 2009) - IHCP, DG Joint Research Centre, European Commission, chapter 4.1.3 the Classification criteria, p. 426 (chapter 4.2.1.4) given in Table 4.1.0, for Chronic category 2 were met. The trigger values are:

•  96 hr LC₅₀ (for fish) >1 to ≤ 10 mg/L (TCP 41.6 mg/L, criterion not met)
• and/or 48 hr EC₅₀ (for crustacea) >1 to ≤ 10 mg/L (TCP 4.1 mg/L, criterion met)

•  and the substance is not rapidly degradable (TCP meets the criterion)
• and/or the experimentally determined BCF ≥ 500 (TCP 5 to 13, criterion not met) or, if absent, the log K_ow ≥ 4,  unless the chronic toxicity NOECs are > 1 mg/L (TCP no NOEC < 1 mg/L but long term data on invertebrates, the most susceptible organism group, lack).

TCP fulfils the criteria for chronic category 2 as it is acute toxic to crustaceans and is not rapidly biodegradable. The "escape clause" NOECs > 1 mg/l for declassification is not applicable as not for all taxa with acute toxicity in the classifiable range (≤ 100 mg/l) exist (IHCP 2009, chapter 4.1.3.4.3, p 434).

Thus according to Regulation (EC) no 1272/2008 of the European parliament and of the council of 16 December 2008 on classification, labelling and packaging of substances, p. L 353/139, the

• The pictogram GHS09 without signal word, the
• Hazard Statement „H411: Toxic to aquatic life with long lasting effects“, and the
• Precautionary Statements Prevention P273, P391 and Disposal P501

apply.