N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine

Endpoint summary

Description of key information

Exposure to the substance during manufacure:
Over a period of 32 years data from one manufactoring site were collected and analyzed to determine the skin sensitizing potential of 6PPD. 70 workers were examined  at regular intervals by the company medical department over the years. The results showed no evidence of a sensitation effects related to the skin exposure to 6PPD suggesting that the personal protective equipment worn during the process was adequate. The risk manangement measures taken at the site correspond to those described for the moderate hazard band.
Exposure to rubber fumes:
75 rubber fume exposure measurements at 9 different rubber manufacturing sites between 2004 and 2007 were performed. Exposures were mostly controlled to less than the UK Workplace Exposure Limit (WEL) of 0.6 mg/m3 (8 hour TWA). Only 6 from 75 exceeded this value. These exposures were measured on reactive site visits, in situations where a HSE inspector had reason to believe that exposure control was inadequate. No exposures in excess of the WEL were measured on the 2007 visits at sites selected at random in an attempt to capture the typical situation within the industry.
The median exposure from 9 sites visited between 2004 and 2007 was 0.13 mg/m3.In a more systematic assessement in the mid to late 1990s, the median exposure was 0.3 mg/m3.
The rubber fume WEL of 0.6 mg/m3 was exceeded at two sites. Six measured exposures, 8% of the measurements taken, exceeded the WEL. In conclusion of the measured data the WEL of 0.6 mg/m3 could therefore be taken as 90th percentile as a worst case. Almost all sites visited had significant deficiencies related to the engineering controls used to control rubber fume exposures. Moulding presses without local exhaust ventilation (LEV) fitted were frequently encountered. Where LEV was installed, deficiencies linked to design, use and maintenance were observed. The use of respiratory protective equipment (RPE) to control fume exposures was uncommon.

Additional information

Risk management measures described in Oberthür (2012), "Erfahrungsbericht über das Sensibilisierungspotential von N-(1 ,3-Dimethylbutyi)-N'-phenyl-p-phenylendiamin (6PPD; CAS: 793-24-8) ", Lanxess Deutschland GmbH, 2012 -10 -24.

EXPOSURE CONTROLS/PERSONAL PROTECTION:

- Protective gloves

- Protective glasses

- Protective helmet

- Protective shoes

- Protective clothing

REGULAR SAFETY INSTRUCTIONS CONCERNING PROTECTIVE CLOTHING, HANDLING AND STORAGE:

- Sectioning (black and white area) acc. to the German standard "GefStoffV"

- Instruction on avoiding skin contact

- Daily change of protective clothing

- Instructions on protective clothing (Dust suit and mask) while cleaning, maintenance and repair work

- Instructions on skin protection, skin cleansing and showering after work

TECHNICAL PRECAUTION:

- local exhaust ventilation at the filling station

- efficient exhaust ventilation in the working area

Details of rubber fume monitoring results according to Keen (2010), "A small survey of exposure to rubber process dust, rubber fume and N-nitrosamines", Health and Safety Executive publication, RR819 Research Report, Derbyshire, UK

Rubber fume exposures (mg/m3) measured by the Health and Safety Laboratory (HSE) between 2004 and 2007:

	number of sites	number of measurements	exposure range	mean	geometric mean	median	results <LOD	results >WEL	sites >WEL
reactive visits	4	45	ND - 1.75	0.27	0.16	0.16	12	6	2
DRP survey	5	30	ND - 0.53	0.15	0.1	0.08	17	0	0
all data	9	75	ND - 1.75	0.22	0.14	0.13	29	6	2

The rubber fume WEL of 0.6 mg/m3 was exceeded at two sites. Six measured exposures, 8% of the measurements taken, exceeded the WEL. In conclusion of the measured data the WEL of 0.6 mg/m3 could therefore be taken as 90th percentile as a worst case. In general a concentration of 3% of the substance in rubber products is assumed and therefore the expected exposure (0.6 mg/m3) can be reduced using a default factor of 0.2. This results in an expected exposure for the substance of 0.12 mg/m3.

This latter mentioned result is in good agreement with exposure data estimated with the program ECETOC TRA where low dustiness was assumed for the uses applied during the production of tyres and GRG and retreating and recycling processes. In conclusion the assumption of low dustiness for the mentioned uses seems to be justifiable.