1

Limit value of 1-hydroxypyrene in urine

for occupational PAH exposure

ISBM Manchester 2013

Frans Jongeneelen

IndusTox Consult

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Take home message

1-Hydroxypyrene in urine (µmol/mol)

1,0 LOL-GEB = Lowest observed level without genotoxic effects in the body

0,0

0,5

1,5

Non-occupational background

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 positiveexperience and a positive attitude to biologicalmonitoring of PAH, however, a biological limit was not proposed

– Employers and Unions requested us to derivean equivalent biological occupational exposure limit (BOEL)

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Updated proposal for BOEL of PAH

Contents

1. Introduction

2. Biological indicators of PAH

3. Biological occupational exposure limit (BOEL)1. Overview existing proposals

2. Updated proposal

4. Message

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Introduction

Biological monitoring of PAH

WorkerUptake of PAH by:

inhalation

dermal absorption

ingestion

Working environment Gaseous and particulate PAH

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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

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Introduction

Biological indicator of PAH

PAH are metabolized in all tissues of the body

Each PAH has different metabolite pattern withvarious toxic and non-toxic metabolites

Hydroxylated-PAH metabolites are rapidlyexcreted in urine. Examples:

– 1- OH-pyrene

– OH-phenantrenes

– 3- OH-b(a)p

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Biological indicator of PAH

Most experience: 1-hydroxypyrene in urine

In humans, pyrene is metabolizedto the main metabolite 1-hydroxypyrene, conjugated and excreted in urine

First proposed as indicator-metabolite in 1985

Often used in scientific studies and field testing of exposure

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Biological indicator of PAH

Other hydroxylated PAH-metabolitesas biological indicator

∑ OH-Phenantrenes– Indicator of volatile PAH

– Example: Germany

Series of up to 10 hydroxylated-PAH metabolites– 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

10Biological 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

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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 1-

hydroxypyrene 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

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Biological occupational exposure limit of urinary 1-hydroxypyrene

Existing biological limits (2)

Organisation Country Type Limit level

(mol/mol)

HSE UK BMGV – not health based, but

based on good hygiene practice

4.0

ACGIH USA

BEI Nq = nonquantitative

Level that warrants occupational

exposure

0.5

In a table:

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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 airborneexposure 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 earlyeffect studies

14Updated biological exposure limit of PAH

Procedure for derivation of level of 1-

hydroxypyrene 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 1-

hydroxypyrene 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)’

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Updated biological exposure limit of PAH

Search for relevant studies

Various bibliographic databases were consulted

Studies from 1990 – 2012

Cross-sectional studies of PAH-exposedworkers

– 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

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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 DNA-

strands

Sister chromatid exchange frequency

High frequency sister chromatid

exchange frequency

SCE

HFC-SCE

Chromosomal disorders

during replication

Micronucleus-test

Cytokinesis Block Micronucleus-test

NucleoPlasmic bridges

Nuclear Buds

MN

CBMN

NPB

NBUD

DNA-damage

(strand breaks)

Single Cell Gel Electrophoresis assay Comet

17Updated biological exposure limit of PAH

Characteristics of studies of PAH-exposed

workers with 1-OH-pyrene and genotoxic effectsNr Study subjects Genotoxic

endpoints

Level of 1-

hydroxypyrene in

urine without

genotoxic effects

(mol/mol)

Pyrene/-

b(a)p ratio

Controlled

for smoking

(Y/N)

Reference

1 Belgian coke oven-

workers + graphite

anode plant workers

SCE

HFC-SCE

MN

1.3 1.5 – 4.5 Y Buchet et al,

1995;

2 Dutch primary

aluminum workers

DNA-adducts 3.8 2 - 30 Y van Schooten

et al, 1995.

3 German coke oven

workers

SCE

Comet-assay

1.9 2.2 Y Popp et al,

1997

4 Swedish potroom

workers

DNA-adducts 4.3 2.8 Y Carstensen et

al, 1999

5 Dutch coke oven

workers

SCE

HFC-SCE

MN

1.1 ? Y Van Delft et al,

2001

6 Polish coke oven-

workers.

SCE

HFC-SCE

MN

Comet-assay

1.0 ? Not needed Siwinska et al,

2004

7 Polish non-smoking

coke oven workers

MN

DNA-adducts

3.1 ? Only non-

smokers

Pavanello et al,

2008

8 Chinese coke oven

workers

MN, NPB’s and

NBUDs

1.3 ? Not needed,

no effect

Duan et al,

2009

9 Chinese coke oven

workers

CBMN 2.4 ? No Guan et al,

2010 (abstract)

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Updated biological exposure limit of 1-hydroxypyrene

Key study: Siwinska et al (2004)

Probability of increased SCE is < 5% at < 1.0 μmol/mol

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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 non-occupational exposure)

Biological limit (as lowest observed level without genotoxic effects in the body)

1-hydroxy-pyreen in urine

End of shift at end of workweek

0.5 mol/mol creatinine 1.0 mol/mol creatinine

20Updated 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 limit 1-hydroxypyrene

(mol/mol cr)

Type

1.5 0,7 Adjusted

2.5 (default) 1.0 Basis

5 1.8 Adjusted

10 3.3 Adjusted

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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 cancerrisk 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

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Take home message

Proposal for occupational exposure limit of 1-hydroxypyrene in urine:

1-Hydroxypyrene in urine (µmol/mol)

1,0 LOL-GEB = Lowest observed level without genotoxic effects in the body

0,0

0,5

1,5

Non-occupational background

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Biological monitoring of PAH

More info?

E-mail: frans.jongeneelen@industox.nl

Voice: +31.24.3528842

Internet: www.industox.nl

Thank you!