4-tert-butylbenzoic acid

Particle size distribution (Granulometry)

Description of key information

EU risk assessment report 2009 (p. 37 -38): PTBBA concentration in air is monitored in PTBBA salt producing plants. Industry has measured the concentration of PTBBA in air during the loading phase by personal and/or static monitoring. The dust was collected during 1 hour with pump and filter system. Two plants reported below 0.01 mg/m3 of PTBBA (analysis of the collected dust with chromatography). The third plant reported 0.05 mg/m3 with a non specific analytical method. Therefore, 0.05 mg/m3 can be regarded as a real worst case for the concentration of PTBBA in air during the loading step. Considering that the process are the same for all the plants run by ESPA (European Stabilisers Producers Association) members, it is justified to consider those data as representative for the whole sector (ESPA, 2007). Information provided by industry for the use of PTBBA as chemical intermediate is confidential and summarised as follows: Workplace air measurements of PTBBA dust at the production of PTBB-ester in 2001 were up to 1.31 mg/m3 (7 samples).
Modelled data
EASE for Windows 2.0, Aug. 1997 was used. EASE estimation for the further processing of PTBBA: Input parameters: T = 20 °C, exposure type is dust, low dust technique, LEV present Level of exposure: 0 - 1 mg/m3
Two granulometric measurements revealed that 0.1 % of the product comprise a particle size below 300 μm and 0.7 % below 100 μm, respectively. Therefore the category “low dust techniques” is chosen.

Additional information

In summary, 0.1 % of a presumably representative PTBBA dust sample in PTBBA-salt-producing plants (in terms of physical characteristics) showed a particle size below 300 μm and 0.7 % below 100 μm, respectively.