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PBT assessment

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PBT assessment: overall result

Reference
Name:
N-isopropylmethacrylamide
Type of composition:
legal entity composition of the substance
State / form:
solid: particulate/powder
Reference substance:
N-isopropylmethacrylamide
PBT status:
the substance is not PBT / vPvB
Justification:

Persistence Assessment:

P criteria:

– the half-life in marine water is higher than 60 days, or

– the half-life in fresh- or estuarine water is higher than 40 days, or

– the half-life in marine sediment is higher than 180 days, or

– the half-life in fresh- or estuarine water sediment is higher than 120 days, or

– the half-life in soil is higher than 120 days

A hydrolysis as a function of pH study (abiotic degradation) conducted at pH 4, pH 7 and pH 9 showed less than 10% hydrolysis after 5 days at 50 °C, equivalent to a half-life greater than 1 year at 25 °C. The substance was determined to be hydrolytically stable.

In a ready biodegradation study the substance attained 14% degradation after 28 days and therefore cannot be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No 301B.

Based on this information, the substance may persist in the aquatic environment and is considered to meet the criteria for persistence (P).

Bioaccumulation Assessment:

B criteria: BCF > 2000.

vB criteria: BCF >5000

No experimental bioaccumulation data is available on the substance and therefore no bioconcentration factor (BCF) is available to directly assess whether the substance meets the bioaccumulation (B) criteria (BCF higher than 2000).

For the PBT and vPvB assessment a screening criterion has been established, which is log Kow greater than 4.5. The assumption behind this is that the uptake of an organic substance is driven by its hydrophobicity. For organic substances with a log Kow value below 4.5 it is assumed that the affinity for the lipids of an organism is insufficient to exceed the B criterion, i.e. a BCF value of 2000 L/kg (based on wet weight of the organism, which refers to fish in most cases).

The partition coefficient of the test item has been determined to be 3.10, log10 Pow 0.491. The substance is therefore considered to have low potential to bioaccumulate and not to meet the criteria for B or vB based on the screening criteria.

An estimate for BCF was run using EPI Suite program Bcfwin (v2.17). The predicted BCF was 1.44, further indicating very low potential for bioaccumulation

Toxicity Assessment:

T critera:

– the long-term no-observed effect concentration (NOEC) for marine or freshwater organisms is less than 0.01 mg/l, or

– the substance is classified as carcinogenic (category 1 or 2), mutagenic (category 1 or 2) or toxic for reproduction (category 1, 2, or 3), or

– there is other evidence of chronic toxicity, as identified by the classifications: T, R48, or Xn, R48 according to Directive 67/548/EEC.

No long-term test results are available for marine or freshwater organisms and therefore no long-term NOEC results are available to compare against the toxicity criteria (NOEC less than 0.01 mg/l).

However, based on results of short-term testing in fish, daphnia and algae it is considered that the T criteria would not be met.

Acute toxicity studies in fish and daphnia showed no effects at the maximum tested concentration of 100 mg ai/l (fish LC50 >100 mg ai/l, NOEC 100 mg ai/l; daphnia EC50 >100 mg ai/l, NOEC 100 mg ai/l).

The algal study showed that the growth rate, yield and biomass of the algae was affected by the presence of the substance.

Although this was a short-term algal test, it can be viewed as providing both acute and chronic endpoints. The 72 hr NOECs were 125 mg ai/L for growth rate, yield and biomass. The 96 hr NOECs were 250 mg ai/L for growth rate and 125 mg ai/L for yield and biomass.

Based on these results to can be anticipated that long-term NOECs would be greater than 0.01 mg/l and the T criteria not met.

The substance is not currently classified as carcinogenic, mutagenic (category 1 or 2) or toxic for reproduction (category 1, 2 and 3) based on available study data. The T criteria is therefore not met for this condition.

The substance is currently classified as STOT-RE Category 2 (Xn, R48/22) based on the results of a combined repeat dose toxicity study with reproduction/developmental toxicity screening test (OECD 422). The study showed minimal axonal swelling with mineralisation in the sciatic nerve in animals of either sex from all treatment groups, which is the basis for the classification.

The T criteria is therefore met for this condition.

Conclusion

Based on the data available, it is considered that the substance meets the criteria for persistence (P) and toxicity (T), but does not meet the criteria for bioaccumulation (B or vB).

The substance is therefore not classed as a PBT or vPvB substance.