1. The document proposes a biological occupational exposure limit (BOEL) for polycyclic aromatic hydrocarbons (PAH) of 1.0 μmol/mol creatinine for 1-hydroxypyrene in urine. This limit is based on the lowest observed level without genotoxic effects found in a meta-analysis of studies. 2. The limit accounts for different PAH profiles by adjusting the limit based on the pyrene to benzo(a)pyrene ratio, with a default ratio of 2.5 corresponding to the proposed limit of 1.0 μmol/mol creatinine. 3. While an occupational exposure limit of 200 ng/m3 for benzo(a)py

1. 1
Limit value of 1-hydroxypyrene in urine
for occupational PAH exposure
Frans Jongeneelen
IndusTox Consult
ISBM Manchester 2013

2. 2
Take home message
1-Hydroxypyrene in urine (µmol/mol)
1,5
1,0
LOL-GEB = Lowest observed level without genotoxic effects in the body
0,5
Non-occupational background
0,0

3. 3
Updated proposal for BOEL of PAH
Reason for new proposal
– New occupational exposure limit (OEL) in
Netherlands for PAH has been proposed

OEL of PAH = 200 ng/m3 as benzo(a)pyrene
– Companies and employees have a positive
experience and a positive attitude to biological
monitoring of PAH, however, a biological limit
was not proposed
– Employers and Unions requested us to derive
an equivalent biological occupational exposure
limit (BOEL)

4. 4
Updated proposal for BOEL of PAH
Contents
1. Introduction
2. Biological indicators of PAH
3. Biological occupational exposure limit (BOEL)
1.
2.
Overview existing proposals
Updated proposal
4. Message

5. 5
Introduction
Biological monitoring of PAH
Working environment
Gaseous and particulate PAH
Worker
Uptake of PAH by:
 inhalation
 dermal absorption
 ingestion

6. 6
Introduction
Occupational PAH-exposure
PAH are present as complex mixtures
In gasphase and particulate matter
Dermal exposure may be significant
PAH-profile varies in between industries
and sometimes within industries
Carcinogenic potency of PAH varies: 4-6
ring components have highest potency
–
–
–
–
–
–
–
Benzo(a)pyrene = carcinogenic PAH with high potency
Pyrene = non-carcinogenic PAH

7. 7
Introduction
Biological indicator of PAH



PAH are metabolized in all tissues of the body
Each PAH has different metabolite pattern with
various toxic and non-toxic metabolites
Hydroxylated-PAH metabolites are rapidly
excreted in urine. Examples:
–
–
–
1- OH-pyrene
OH-phenantrenes
3- OH-b(a)p

8. 8
Biological indicator of PAH
Most experience: 1-hydroxypyrene in
urine



In humans, pyrene is metabolized
to the main metabolite 1hydroxypyrene, conjugated and
excreted in urine
First proposed as indicatormetabolite in 1985
Often used in scientific studies
and field testing of exposure

9. 9
Biological indicator of PAH
Other hydroxylated PAH-metabolites
as biological indicator

∑ OH-Phenantrenes
–
–

Series of up to 10 hydroxylated-PAH metabolites
–
–

Indicator of volatile PAH
Example: Germany
Not widely used
Example: US NHANES-study
3-OH-B(a)P
–
–
–
B(a)P is indicator of risk of PAH
Low concentrations in urine
Little experience, few labs

10. Biological indicator of PAH
Present status of monitoring of
PAH-metabolites in urine
– 3-OH-B(a)P has potential as bioindicator

Metabolite of B(a)P, the PAH with high carcinogenic
potency, but:
– Few labs, limited experience
– Excretion kinetics?
– Rubustness analytical method?
– 1-Hydroxypyrene is sound bioindicator
Many studies from various industries & countries
shows that it is a valuable tool for controlling exposure
 Analytical method has proven to be solid
 Elimination rate is known => end-of-workweek post
shift urine sampling

– However, pyrene content varies, adjustment is needed for
health risk assessment
10

11. 11
Biological occupational exposure limit of urinary 1-hydroxypyrene
Existing biological limits (1)
HSE - UK 2004: Biological monitoring guidance value
 Control-based biological monitoring guidance value
 Based on 90th-percentile of urine levels of workers in
‘good hygiene practice’ industries
 Benchmark value: 4.0 μmol/mol creat
ACGIH - USA 2005: Biological exposure index
 Health-based biological exposure index of 1hydroxypyrene in urine scientifically not justified, due to
insufficient data: No BEI!
 However, measurement of 1-hydroxypyrene is valuable
tool for controlling exposure
 Recommendation: control exposure towards the level in
general population

Reference level as 99-percentile of general
population = 1.0 μg/L = 0.5 μmol/mol creaat

12. 12
Biological occupational exposure limit of urinary 1-hydroxypyrene
Existing biological limits (2)
In a table:
Organisation
Country
HSE
UK
Type
BMGV – not health based, but
based on good hygiene practice
BEI
ACGIH
Limit level
(mol/mol)
4.0
Nq = nonquantitative
USA
Level that warrants occupational
exposure
0.5

13. 13
How to derive the biological limit that is
equal to health risk of exposure to 200
ng/m3 b(a)p?
Two indirect approaches are possible:
1.
Estimate urine level in workers equal to airborne
exposure at 200 ng/m3 b(a)p from meta-analysis of
cross-sectional exposure studies
2.
Derive urine level in workers without early genotoxic
effects from meta-analysis of cross-sectional early
effect studies

14. Updated biological exposure limit of PAH
14
Procedure for derivation of level of 1hydroxypyrene in urine without genotoxic
effects
1.
Search in scientific literature for cross-sectional studies
of PAH-exposed workers with:


One or more genotoxic effect markers (in lymphocytes)
Determination of 1-hydroxypyrene in urine as exposure
indicator
2.
Analyse each study and estimate the level of 1hydroxypyrene in urine at which no genotoxic effect was
observed.
3.
Select study with lowest effect level as key-study. This
key-study holds: ‘Lowest observed level without
genotoxic effect`in the body (= LOL-GEB)’

15. 15
Updated biological exposure limit of PAH
Search for relevant studies
 Various
bibliographic databases were consulted
 Studies from 1990 – 2012
 Cross-sectional studies of PAH-exposed
workers
– with genotoxic effects in lymphocytes
– with 1-hydroxypyrene in urine
– threshold of genotoxic effect(s) can be derived
9 Studies were found, that met the criteria

16. 16
Updated biological exposure limit of PAH
Biomarkers of genotoxicity in studies of
PAH-exposed workers
Endpoint
Name of test
In short
Chromosomal disorders
in structure or number
Chromosomal aberrations
CA
Breaks in and
exchanges of DNAstrands
Sister chromatid exchange frequency
SCE
High frequency sister chromatid
exchange frequency
HFC-SCE
Chromosomal disorders
during replication
Micronucleus-test
MN
Cytokinesis Block Micronucleus-test
CBMN
NucleoPlasmic bridges
NPB
Nuclear Buds
NBUD
Single Cell Gel Electrophoresis assay
Comet
DNA-damage
(strand breaks)

17. 17
Updated biological exposure limit of PAH
Characteristics of studies of PAH-exposed
workers with 1-OH-pyrene and genotoxic effects
Nr
Study subjects
Genotoxic
endpoints
1
Belgian coke ovenworkers + graphite
anode plant workers
Dutch primary
aluminum workers
SCE
HFC-SCE
MN
DNA-adducts
German coke oven
workers
Swedish potroom
workers
5
Dutch coke oven
workers
6
Polish coke ovenworkers.
7
Polish non-smoking
coke oven workers
Chinese coke oven
workers
Chinese coke oven
workers
2
3
4
8
9
Level of 1Pyrene/hydroxypyrene in b(a)p ratio
urine without
genotoxic effects
(mol/mol)
1.3
1.5 – 4.5
Controlled
for smoking
(Y/N)
Reference
Y
Buchet et al,
1995;
3.8
2 - 30
Y
van Schooten
et al, 1995.
SCE
Comet-assay
DNA-adducts
1.9
2.2
Y
4.3
2.8
Y
Popp et al,
1997
Carstensen et
al, 1999
SCE
HFC-SCE
MN
SCE
HFC-SCE
MN
Comet-assay
MN
DNA-adducts
MN, NPB’s and
NBUDs
CBMN
1.1
?
Y
Van Delft et al,
2001
1.0
?
Not needed
Siwinska et al,
2004
3.1
?
1.3
?
2.4
?
Only nonsmokers
Not needed,
no effect
No
Pavanello et al,
2008
Duan et al,
2009
Guan et al,
2010 (abstract)

18. 18
Updated biological exposure limit of 1-hydroxypyrene
Key study: Siwinska et al (2004)
Probability of increased SCE is < 5% at < 1.0 μmol/mol

19. 19
Updated biological exposure limit of PAH
Proposed biological occupational
exposure limit (as 1-hydroxypyrene in urine)
Biological
parameter
Valid as
Reference value
(as upper bound of nonoccupational exposure)
1-hydroxypyreen in urine
End of shift at
end of
workweek
0.5 mol/mol creatinine
Biological limit
(as lowest observed level
without genotoxic effects
in the body)
1.0 mol/mol creatinine

20. 20
Updated biological exposure limit of PAH
PAH-profile adjustment of biological
occupational exposure limit

Biological occupational exposure limit is valid at
coke oven type exposure with a pyrene/benzo(a)pyrene ratio of 2.5

Adjust limit for deviating pyrene/benzo(a)pyrene
ratios. Linear adjustment results in:
pyrene/benz(a)pyrene
ratio
1.5
2.5 (default)
5
10
limit 1-hydroxypyrene
(mol/mol cr)
0,7
1.0
1.8
3.3
Type
Adjusted
Basis
Adjusted
Adjusted

21. 21
Updated biological exposure limit for 1-hydroxypyrene
Discussion

Is risk level of OEL of 200 ng/m3 B(a)P
equal to risk level of updated BOEL?
Nowadays carcinogens often have risk-based limits
 OEL of 200 ng/m3 B(a)P is based on annual cancer
risk between 1: 10.000/year and 1:1.000.000/year
 Cancer risk of BOEL of 1.0 mol/mol is ??????


Interference of smoking?


BOEL derived form group of non-smoking workers
Legal status of proposal?

Proposal will be discussed in advisory counsel SER
of Netherlands
– Representatives of employers & unions

Expected result
– No legal status, supplemental industry-adopted limit

22. 22
Take home message
Proposal for occupational exposure limit of 1hydroxypyrene in urine:
1-Hydroxypyrene in urine (µmol/mol)
1,5
1,0
LOL-GEB = Lowest observed level without genotoxic effects in the body
0,5
Non-occupational background
0,0

23. 23
Biological monitoring of PAH
More info?
E-mail: frans.jongeneelen@industox.nl
Voice: +31.24.3528842
Internet: www.industox.nl
Thank you!