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PBT assessment: overall result

PBT status:
the substance is not PBT / vPvB

Classification of tert-butyl-4-methoxyphenol for effects in the environment

Several major guideline – estimation values (Klimisch 2) are available for tert-butyl-4-methoxyphenol, which indicates considerable toxic effect in the three key trophic levels (fish, invertebrates and algae) when exposed to the substance, tert-butyl-4-methoxyphenol at concentrations up to its limit of solubility in the respective test media. Among the values lower values which lead to the classification of the substance the value which have been considered for further calculation (algae) is EC50 = 1.9 mg/L.


In determining the classification appropriate to tert-butyl-4-methoxyphenol, it is necessary to consider all available evidence concerning its persistence, potential to accumulate and predicted or observed environmental fate and behaviour that may present a long-term and/or delayed danger to the structure and/or functioning of aquatic ecosystems. These points are considered below.



Reliable studies are available to demonstrate that tert-butyl-4-methoxyphenol is non persistent in nature and so is considered to be biodegradable in the environment. In other words tert-butyl-4-methoxyphenol may therefore be expected to degrade rapidly. Thus it can be inferred that tert-butyl-4-methoxyphenol is non persistent in environment. 


Potential to accumulate

Predicted and measured log Kow values for tert-butyl-4-methoxyphenol are less than 4 (Log Kow = 1). The potential for tert-butyl-4-methoxyphenol to bioaccumulate in the tissues of organisms that inhabit aquatic or terrestrial matrices is negligible as the BCF factor for the substance is less than 1000.  


Thus,tert-butyl-4-methoxyphenolis non persistent and does not satisfy the criteria for classification as persistent (P). 


The calculated BCF of cinnamaldehyde is 57.07 dimensionless and below the threshold of 2000. 


So,tert-butyl-4-methoxyphenoldoes not satisfy the criterion for classification as bioaccumulative (B).


The toxicity values of fish, invertebrates and algae are LC50 = 2.5 mg/L, EC50 = 2.3 mg/L are EC50 = 1.9 mg/L, respectively. All the values of the 3 trophic levels fall in the criteria for classification (as per CLP regulation in category 2) and so will not qualify for classification as per the CLP regulation in the above mentioned criteria.

Tert-butyl-4-methoxyphenoldoes satisfy the environmental effects criterion for classification as toxic (T).


Tert-butyl-4-methoxyphenolis not P & B (or vPvB) substance, but will qualify as T.