Registration Dossier

Administrative data

Endpoint:
monitoring data
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
2010
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Comparable to guideline study with acceptable restrictions. The data are considered to be of high quality and generated with conservative or realistic assumptions for the following reasons: •The experimental work and evaluation was supervised by a single study director. •Sampling was performed based on clear written protocols and by a predefined and representative sample of manufacturing sites in the Europan Union. •All samples were analysed with a validated method in one laboratory certified according to ISO 17025. •The data is likely to represent the worst case as the local concentrations in environmental compartments were calculated with EUSES with the conservative assumptions of a standard STP and a standard receiving river. In those cases where the RCR was >1, real data for the size of the STP and the receiving river were used. •The quality of the data was compared to the criteria as stated in OECD (2000), cf. Appendix 1. The requirements for the ideal set were generally met.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010
Report Date:
2010

Materials and methods

Test guideline
Guideline:
other: monitoring data
Deviations:
not applicable
Principles of method if other than guideline:
Two types of statistical examination were applied to the data generated:
•In the first approach (“weighted average”) the amount of 6PPD used was averaged on a regional level and compared with the outcome of the analytical monitoring. This resulted in a mean emission factor of 1.5*10-5. This approach bears the risk of being misleading since the release factor averaged on a regional scale systematically tends to result in a “non-safe” situation being predicted for larger sites although they would be safe when considering the measured concentrations in the waste water, and to overlook potentially “unsafe” situations for small scale users which are always regarded as “safe”.
•A second “local percentile approach” was regarded as more realistic: Each site was considered individually. The risk characterisation ratios (RCR´s) were calculated by means of the individual waste water load per site. Subsequently, EUSES estimations were performed using actual site data.
In detail:
As 6PPD is the PPD with the highest tonnage used in Europe, this substance was selected as a representative for the whole class of PPDs. Beside 6PPD, waste water was also analysed for the 6PPD hydrolysis product 4-hydroxydiphenylamine (4-HDPA). Recalculated as the 6PPD equivalent and multiplied with the effluent volume, the total waste water load was:
a)compared to the tonnage used at each individual site resulting in an emission factor (weighted average approach) per site
b)evaluated with EUSES 2.1 in order to get estimated (modelled) information on concentrations in the relevant environmental compartments (water, sediment, soil, sludge). These data were then divided by the PNECs previously calculated for 6PPD, resulting in the risk characterisation ratio (RCR) for each site and environmental compartment.
GLP compliance:
no
Type of measurement:
other: concentration of substance in waste water (total effluent/ partial effluent)
Media:
other: waste water

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Type:
Constituent
Details on test material:
As the test substance, 6PPD, is not hydrolytically stable, the major hydrolysis product, 4-Hydroxydiphenylamine, CAS 122-37-2, was analysed in this study as well. The measured concentrations of 4-HDPA were expressed as 6PPD equivalents, so that the total release of the test substance could be calculated.

Study design

Details on sampling:
Sampling bottles (brown glass) were provided by Currenta and sent to the contact persons at each site. Waste water from 25 representative rubber manufacturing sites in Europe (France, Germany, Italy, Poland, Spain, UK), including tyre and general rubber goods manufacturing, were sampled and analysed for 6PPD and the hydrolysis product 4-hydroxydiphenylamine (4-HDPA). Sampling was performed by local experienced personnel and were taken out of the waste water stream before entering the biological waste water treatment plant (1st priority, total effluent) or after the mechanical treatment (if present), before different waste water streams are merged together (2nd priority, partial effluent).
Bottles (2x1L) filled with waste water were sent back to Currenta for analysis; all samples arrived in good condition.

Results and discussion

Details on results:
Safe use for a site is demonstrated for a waste water load of up to 3.5 kg/year, emitting to a standard sewage treatment plant (10,000 inhabitants) and a standard river (20,000 m3/day). This amount is reduced to 1.5 kg/year if sewage sludge generated in the STP is applied to agricultural soil. These quantities have been identified using EUSES for a RCR = 1, based on the physicochemical properties and PNECs of 6PPD.

Any other information on results incl. tables

The measured waste water data were processed with EUSES v. 2.1. EUSES takes all relevant physico-chemical properties of 6PPD into account. Six of the 21 sites did not discharge waste water into STP. These sites were calculated with EUSES without STP. As in the first approach some of the sites appeared unsafe, refinements were performed using site specific data:

•size of the STP

•information about application of sludge to agricultural soils

•water flow of the receiving river.

The emissions to waste water, as well as the resulting concentrations in the relevant compartments, were evaluated in order to get the 90th-percentile:

 Environmental compartment  90th percentile
 total emission to waste water (kg/year) 5.61
 PEClocal, freshwater (µg/L) 0.25
 PECsoil (µg/kg ww) 32.3 
 PECstp (µg/L) 0.3 

Applicant's summary and conclusion

Conclusions:
The total emission of the test substance to waste water could be measured to reach a value of 5.61 kg/year (90th percentile).
Executive summary:

Waste water from 25 representative rubber manufacturing sites in Europe (France, Germany, Italy, Poland, Spain, UK), including tyre and general rubber goods manufacturing, were sampled and analysed for 6PPD and the hydrolysis product 4-hydroxydiphenylamine (4-HDPA). Additional information was collected from individual sites, mainly on tonnages, waste water flow and relevant production conditions.

The total emission of the test substance to waste water could be measured to reach a value of 5.61 kg/year (90th percentile). Inserting this data into the estimation program EUSES the following result was determined:

Safe use can be demonstrated for a site with a waste water load of 6PPD of up to 3.5 kg/year, emitting to a standard sewage treatment plant (10,000 inhabitants) and to a standard river (20,000 m3/day). This amount is reduced to 1.5 kg/year if the sewage sludge generated in the sewage treatment plant (STP) is applied to agricultural soil. 

Statistical evaluation showed that with regard to local concentrations in receiving rivers and the concentration in agricultural soils, safe use is established using the 90thpercentile of the rubber manufacturing sites.