Registration Dossier

Administrative data

Endpoint:
basic toxicokinetics in vivo
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Data source

Reference
Reference Type:
publication
Title:
Test chamber exposure of humans to 1,6-hexamethylene diisocyanate and isophorone diisocyanate
Author:
Tinnerberg H, Skarping G, Dalene M and Hagmar L
Bibliographic source:
Int. Arch. Occup. Environ. Health 67, 367-374
Report Date:
1995

Materials and methods

Objective of study:
toxicokinetics
Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Human inhalative exposure to the test item Isophorone diisocyanate (IPDI). Determination of the IPDI content in blood and urine (analytical determination of the corresponding Isophorone diamine (IPDA) determined as IPDA-pentafluoropropionic anhydride) and determination of urinary IPDI excretion.
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Details on test material:
Isophorone diisocyanate (IPDI) was obtained from Aldrich Chemie (Steinham, Germany); purity not reported
Radiolabelling:
no

Test animals

Species:
human
Strain:
other: healthy non-smoking volunteers
Sex:
male
Details on test animals and environmental conditions:
- Three male healthy non-smoking volunteers
- 26, 28 and 50 years of age
- Body weights: 70 kg; 81 kg; 70 kg
- volunteers were interwieved for health history and exmined by a physican before the experimental phase
- Study was approved by the Ethics Committee at Lund University. all participiants gave written informed consent

Administration / exposure

Route of administration:
inhalation: aerosol
Vehicle:
other: air
Details on exposure:
- Three healthy male volunteers were exposed simultaneously in a 5.6 m3  exposure chamber to concentrations of 12.1 (Tuesday),
 17.7 (Thursday),  and 50.7 (Saturday) ug isophorone diisocyanate/m3 for 2 hours per  concentration level. 
- The inhaled doses were estimated by pulmonary ventilation x exposure  level x duration of exposure.
Duration and frequency of treatment / exposure:
Each volunteer was exposed to three different concentrations of the test item (12.1 (Tuesday),
 17.7 (Thursday),  and 50.7 (Saturday) ug isophorone diisocyanate/m3). The duration of each exposure was 2 hours.
Doses / concentrations
Remarks:
Doses / Concentrations:
Each volunteer was exposed to three different concentrations of the test item (12.1 (Tuesday),
17.7 (Thursday),  and 50.7 (Saturday) ug isophorone diisocyanate/m3)
No. of animals per sex per dose:
3 human male volunteers. Each volunteer was exposed to the three different concentrations.
Control animals:
no
Positive control:
no positive control
Details on study design:
- Three healthy male volunteers were exposed simultaneously in a 5.6 m3  exposure chamber to concentrations of 12.1 (Tuesday),
 17.7 (Thursday),  and 50.7 (Saturday) ug isophorone diisocyanate/m3 for 2 hours per  concentration level. 
- The inhaled doses were estimated by pulmonary ventilation x exposure  level x duration of exposure.
- All urine was collected for 16 days.
- Blood samples were taken before and half an hour after exposure plus  daily on exposure-free days.
- Samples were hydrolyzed, i.e. conjugates were split and any residual  isophorone diisocyanate was converted to isophorone diamine (IPDA)
(CAS No.  2855-13-2).
- This diamine was determined as its pentafluoropropionic amide by liquid  chromatography / mass spectrometry.
Details on dosing and sampling:
- Three healthy male volunteers were exposed simultaneously in a 5.6 m3  exposure chamber to concentrations of 12.1 (Tuesday),
 17.7 (Thursday),  and 50.7 (Saturday) ug isophorone diisocyanate/m3 for 2 hours per  concentration level. 
- The inhaled doses were estimated by pulmonary ventilation x exposure  level x duration of exposure.
- All urine was collected for 16 days.
- Blood samples were taken before and half an hour after exposure plus  daily on exposure-free days.
- Samples were hydrolyzed, i.e. conjugates were split and any residual  isophorone diisocyanate was converted to isophorone diamine (IPDA)
(CAS No.  2855-13-2).
- This diamine was determined as its pentafluoropropionic amide by liquid  chromatography / mass spectrometry.
Statistics:
not reported

Results and discussion

Preliminary studies:
no information

Toxicokinetic / pharmacokinetic studies

Details on absorption:
no information
Details on distribution in tissues:
details on distribution in tissues not known
Transfer into organs
Test no.:
#1
Transfer type:
other: not described; No isophorone diamine (IPDA) could be detected in hydrolysed plasma
Observation:
not determined
Details on excretion:
Urinary excretion:
-The average urinary elimination half-time was 2.8 hours. 
-The average  urinary excretion was 27 % (range 19-46%). 
- An association between the  estimated inhaled dose and the total excreted amount was seen.
Toxicokinetic parametersopen allclose all
Test no.:
#1
Toxicokinetic parameters:
half-life 1st: 2.8 h
Test no.:
#1
Toxicokinetic parameters:
other: urinary excretion was 27 % 

Metabolite characterisation studies

Metabolites identified:
yes
Details on metabolites:
Isophorone diisocyanate (IPDI) hydrolyses to the corresponding amine Isophorone diamine(IPDA). Because no IPDA was found in unhydrolysed urine samples the authors conclude that IPDA is covalently bonded.

Any other information on results incl. tables

The detection limit was about 0.1 µg/l in urine and  0.1 µg/l in plasma. No isophorone diamine was found in hydrolyzed plasma. When working up samples from exposed persons without hydrolysis, no isophorone diamine was seen.

Applicant's summary and conclusion

Conclusions:
The average urinary elimination half-time was 2.8 hours. The average  urinary excretion was 27 % (range 19-46%). An association 
between the  estimated inhaled dose and the total excreted amount was seen. The detection limit was about 0.1 µg/l in urine and < 0.1 µg/l in plasma. No isophorone diamine was found in hydrolyzed plasma. When working up samples from exposed persons without hydrolysis, no  isophorone diamine was seen. The authors conclude that IPDA is covalently bonded. Analysis of urine regarding Isophorone diamine, which is a hydrolysis product of Isophrone diisocyanate (IPDI) can be used as biomarker for exposure to IPDI.
Executive summary:

A method was developed to determine the test item Isophorone diisocyanate (IPDI) in blood and urine via detection of Isophorone diamine (IPDA) measured as as IPDA-pentafluoropropionic anhydride in humans exposed to IPDI by inhalation. The optimal hydrolysis condition was found giving the highest yield of IPDA in urine (hydrolysis with 3M NaOH during 4 h). The average urinary elimination half-time was 2.8 hours. The average  urinary excretion was 27 % (range 19-46%). An association between the  estimated inhaled dose and the total excreted amount was seen. When working up samples from exposed persons without hydrolysis, no isophorone diamine (IPDA) was seen. This means, that no free IPDA was present in the urine after exposure to IPDI. Hence, IPDA is covalently bonded in urine. No IPDA could be found in hydrolysed plasma ( ca 0.1µg/l), which could not be explained.