p-(1,1-dimethylpropyl)phenol

Bioaccumulation: aquatic / sediment

Description of key information

Modeled BCF value, based on the measured Kow of 3.6, was estimated to be 229 L/kg. 

Key value for chemical safety assessment

BCF (aquatic species):

229 L/kg ww

Additional information

Reliable measured bioconcentration information is not available for p-tert-amylphenol, although modeled data are presented below.

The European Union System for the Evaluation of Substances (EUSES) model was used to estimate bioconcentration for p-tert-amylphenol. Using the measured log Kow of 3.6, a BCF for fish was estimated at 229 L/kg wt.

In a memorandum by S. Gowda of USEPA (September 29, 2005) a BCF value of 205.7 (log BCF = 2.313) was calculated for p-tert-amylphenol, based on a Log Kow of 3.91 using the software EPISuite.  

Sundt and Baussant (2003) conducted a BCF study (Klimisch 3) with fish where the uptake, tissue distribution and elimination of 4-tert-butylphenol using seawater and dietary exposure were investigated. This study had significant methodological deficiencies (i.e., no controls, one test concentration and inappropriate number of fish per replicate) but is presented here for comparison. Although no guideline was specified, farmed juvenile Atlantic cod (Gadus morhua) were exposed to one measured radio-labelled concentration (0.008 ug/L) of p-tert-butylphenol in a flow-through system with seawater for 8 days followed by an 8 day depuration period. In the dietary study, juvenile Atlantic cod were fed a daily dose in food corresponding to 5 μg/kg of test substance per fish. One fish from three replicates were sampled for kinetic analyses at multiple intervals for both dietary and waterborne exposures. Liver and remaining body tissue were analyzed separately. Uptake and elimination rates were estimated by a first-order kinetic model.  Steady-state was reached within 2 days for the seawater exposure. The modelled BCF was 194 L/kg and the experimental BCF after the 8 day exposure was 125 L/kg for the seawater exposure. The dietary study resulted in similar uptake and elimination pattern. However, the dietary BCF was much lower where the modelled BCF was 0.14 L/kg and the experimental BCF, after the 8 day exposure, was 0.2 L/kg.

The Environmental Risk Assessment Report:4-tert-pentylphenol (CAS no. 80-46-6) (Environment Agency, 2008) (RAR) provides supportive evidence of the unlikely bioaccumulation of p-tert-amylphenol in aquatic organisms as quoted below.

“A fish BCF of 501 L/kg may be estimated from the log Kow (4.0) using the QSAR recommended in the Technical Guidance Document (EC2003). A slightly lower BCF of 240 L/kg can be estimated from the same log Kow using the BCFWIN v2.17 model (US EPA, 2007a). In mammals, phenolic compounds are rapidly glucuronidated or sulphated, followed by excretion via the urine or feces (see Section 4.4.1.1). The same principal metabolic pathways occur in both mammals and fish, so the predicted fish BCF of ~500 L/kg is possibly an overestimate. However, studies have shown that a range of alkylphenols may accumulate in fish bile to higher levels than might be expected from the Kow (e.g. Larssonet al., 1999; Gibson et al., 2005).”

Reliable modeled BCF value for p-tert-amylphenol, using the measured log Kow of 3.6 was estimated to be 229 L/kg wt for fish. Other modeled data and supporting data for the structural analogue, indicate that there may be low potential for bioaccumulation of p-tert-amylphenol. Although the RAR concludes that the study values suggest a modest potential for p-tert-amylphenol to bioconcentrate, the report concludes that the modeled BCF may be overestimated. In all cases, though, BCF values are well below the REACH bioaccumulation criterion (B) of 2000.