Dinoseb

PBT assessment

PBT assessment: overall result

PBT status:

the substance is not PBT / vPvB

Justification:

Dinoseb is considered to fulfil the Toxic criteria of the PBT assessment but does not fulfil either the Persistent or Bioaccumulative criteria. The substance is not considered to be a PBT or vPvB substance.

Persistence assessment

In accordance with Annex XIII to Regulation 1907/2006 the criteria for persistence are as follows:

A substance fulfils the persistence criterion (P-) when:

— 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.

The assessment of the persistency in the environment shall be based on available half-life data collected under the adequate conditions, which shall be described by the registrant.

Although the field studies conducted on the material suggest that the substance may persist in the environment, Dinoseb can be classified as inherently biodegradable – not fulfilling criteria. However, biodegradation was observed in the ready biodegradability study with 24% mineralisation within 29 days. Furthermore, extensive metabolism and mineralisation of Dinoseb by isolated soil microorganism cultures was observed. Therefore, it is likely that Dinoseb will completely be degraded in the STP at it is expected to be found at low concentration. Marine waters and sediments are unlikely to be exposed to Dinoseb following its manufacturing; due to the low expected emission. However, it is considered highly unlikely that the half-lives would differ significantly from those demonstrated in freshwater systems. It is therefore concluded that Dinoseb does not satisfy the persistence criteria(not P or vP).

 

Bioaccumulation assessment

A substance fulfils the bioaccumulation criterion (B-) when:

— the bioconcentration factor (BCF) is higher than 2 000.

Based on the experimental BCF value of 1.4 and the log Pow value of 1.26, the compound is not expected to bioaccumulate.

Dinoseb can be concluded not to fulfil bioaccumulation criteria(not B or vB).

 

Toxicity assessment

 

In accordance with Annex XIII to Regulation 1907/2006 the criteria for toxicity are as follows:

 

A substance fulfils the toxicity criterion (T-) when:

— 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.

The NOEC, from long-term toxicity study with aquatic organisms, ranges from 0.015 mg/L to 49 mg/L (fish) to 0.03 mg/L for growth inhibition of green algae. The aquatic NOECs are above the trigger value of 0.01 mg/l and therefore the substance does not fulfil the criterion “T”.

Dinoseb is not classifiable as to the human carcinogenicity according to the US EPA However the substance is classified on Annex I of Directive 67/548/EEC as a Category 2 reproductive toxicant and therefore Dinoseb fulfils the Toxicity criteria(T).