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Investigation of irritative and genotoxic effects of vapours and - - PDF document

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German Human Bitumen Study Irritative and Genotoxic Effects of Vapours and Aerosols of Bitumen Monika Raulf-Heimsoth Institute for Prevention and Occupational Medicine of the German Social Accident Insurance, Institute of the Ruhr

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SLIDE 1

German Human Bitumen Study Irritative and Genotoxic Effects

  • f Vapours and Aerosols of

Bitumen

Monika Raulf-Heimsoth

Institute for Prevention and Occupational Medicine

  • f the German Social Accident Insurance, Institute
  • f the Ruhr University Bochum (IPA)

Director: Prof. Dr. Thomas Brüning, Bürkle-de-la-Camp-Platz 1, 44789 Bochum

EAPA Symposium, 20th of May 2010, Madrid, SPAIN

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  • Of specific concern is the potential carcinogenicity of

the inhalation of fumes of bitumen. ⇒ IARC classification 1985/87: possible human carcinogen ⇒ MAK Germany 1977: suspected carcinogen

  • In 2001, the German Committee for Hazardous Substances

(AGS) lowered the threshold limit value for vapours and aerosols of bitumen to 10 mg/m3; for mastic asphalt workers the exposure limit value was temporarily deferred.

  • In 2005 all technical based threshold limit values have been

suspended.

  • A mortality analysis of non-malignant diseases revealed

the highest mortality from respiratory diseases in pavers and mastic asphalt workers (Randem, 2003).

  • Data on irritative/genotoxic effects of bitumen under current

exposure conditions in humans are limited.

Health hazards of vapours and aerosols of bitumen

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SLIDE 2

3 / 41

Investigation of irritative and genotoxic effects of vapours and aerosols of bitumen in particular for mastic asphalt

Assignment of the German Bitumen Forum 2000

4 / 41

Bitumen Forum

External cooperation

Ambient Monitoring Biological Monitoring

Human Bitumen Study

Bit-Imm chemical- irritative effects Bit-Tox genotoxic effects Bit-Mol enzyme mutations Bit-Med lung function Bit-Epid epidemiol. analysis

IPA project-related committee

ITEM DREAM IPASUM BG-Bau

BIU IFA, Ergo

Uni Gießen

German Human Bitumen Study

IPA IPA IPA IPA

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SLIDE 3

5 / 41

Cross-shift Design

Before shift

Questionnaire Lung function measurement Air sampling Spot urine Nasal lavage fluid Induced sputum

After shift

Lung function measurement Spot urine Nasal lavage fluid induced sputum

During shift

Blood Blood

Description of the workplaces PAH metabolites

Irritative effects

Genotoxic effects

6 / 41

Study group

Study population n=438

Reference group n=118

Workers with exposure to vapours and aerosols of bitumen n=320

Examination of 500 workers

51 construction sites 22 construction sites

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SLIDE 4

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Attribute References Exposed (total) n=118 n=320

Exposure to vapours and aerosols of bitumen* (mg/m3) (median; IQR) 0.17 (0.07-0.3) (n=69) 3.46 (1.8-5.9) Age (years) (median; range) 41 (18-64) 41 (17-63) Current smoking n (%) 61 (51.7%) 199 (62.2%) German nationality n (%) 96 (81.4%) 218 (68.3%)

Characteristics of the study population

* Mineral oil standard

8 / 41

External exposure

  • personal measurements
  • vapours and aerosols
  • stationary measurements
  • vapours/aerosols
  • 16 EPA-PAH

⇒ During the whole shift

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SLIDE 5

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Bitumen is a complex mixture of organic compounds Lack of a specific method to measure bitumen exposure

Sampling and analysis are different

U.S.: 37-mm cassette < inhalable fraction Germany: GGP sampler inhalable fraction U.S: NIOSH method 4502 Benzene-soluble matter in aerosols Germany: BGIA method 6305; C-H stretches in vapours and aerosols U.S.: benzene-soluble matter Germany: C-H stretches, mineral-oil standard until 2008

External exposure

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Background “bitumen” exposure up to 1 mg/m3 according to BGIA method 6305

< , 4 , 4

  • ,

7 , 7

  • ,

1 , 1

  • ,

2 , 2

  • ,

3 , 3

  • ,

5 , 5

  • ,

8 , 8

  • 1

, 4 1 , 4

  • 2

2

  • 4

4

  • 6

6

  • 1

1

  • 1

6 1 6

  • 2

7 > 2 7 *

20 40 60 80 Reference group median 0,20 mg/m³ Exposed workers, median 3,46 mg/m³

Number of workers 9.1% of the exposed workers > 10 mg/m³ Vapours and aerosols of bitumen

*Numbers are rounded.

Reference group P95 = 1.10 mg/m³

Assessed with the BGIA method 6305

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SLIDE 6

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Summary I

  • Lack of a specific method to measure bitumen exposure
  • Significant disparity in the sampling and analytical methods

between various countries

  • In Germany: GGP sampler; inhalable fraction; BGIA method

6305: C-H stretches in vapours and aerosols

  • Background exposure up to 1.1 mg/m3 has to be

considered

  • Frequent changes of the construction sites and of the workplace

conditions impair the assessment of lifetime exposure

  • Reduction of the exposure to vapours and aerosols of bitumen

by lowering the application temperature

  • A single shift measurement of bitumen is not sufficient to

serve as a proxy for an average or lifetime exposure.

12 / 41

Bitumen exposure Metabolism

Biological Monitoring

Urinary PAH metabolites

  • 1-Hydroxypyrene (1-OHP)
  • Di-Hydroxypyrene
  • 1-Naphthol
  • 2-Naphthol
  • 1-OH-Phenanthrene
  • 2-OH-Phenanthrene
  • 3-OH-Phenanthrene
  • 4-OH-Phenanthrene
  • 9-OH-Phenanthrene
  • Phenanthrene tetrol
  • 1,2-Phen-Diol
  • 9,10-Phen-Diol

Σ OHPHE

Urinary metabolites

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SLIDE 7

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1 10 100 1000 10000 100000

Non-smokers Smokers Reference- group Reference- group Exposed workers Exposed workers

57 120 60 196 57 119 61 198 = N

pre shift post shift

GerES* P95 760 ng/L P50 170 ng/L German males * GerES: German Environmental Survey (1998)

1-hydroxypyrene [ng/L]

Smoking and bitumen exposure contribute to 1-OHP

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1-Hydroxypyrene concentrations post shift in exposed and non-exposed non-smokers

< . 1 . 1

  • .

2 . 2

  • .

4 . 4

  • .

9 . 9

  • .

1 8 . 1 8

  • .

3 7 . 3 7

  • .

7 6 . 7 6

  • 1

. 6 1 . 6

  • 3

. 2 3 . 2

  • 6

. 5 > 6 . 5 *

10 20 30 40 50 Reference group Median 0.13 µg/L Exposed workers, Median 0.44 µg/L

Number of workers

22 % of exposed non-smokers >P95 = 0.76 µg/L in the general population

1-Hydroxypyrene (µg/L)

* Numbers are rounded .

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SLIDE 8

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Mixed linear model for 1-hydroxypyrene (1-OHP)*

* Adjusted for age, creatinine, and German nationality

200 400 600 800 Reference group, Non-smoker Reference group, Smoker Exposed, Non-smoker Exposed, Smoker Pre shift Post shift p < . 1 p < 0.0001 p = 0.002 p = 0.102 p = 0.004 p = 0.0001 Time of measurement 1-Hydroxypyrene (ng/L)

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Conclusions on PAH metabolite analysis in the Human Bitumen study

  • Bitumen exposure during shift was associated with an

increase of certain PAH metabolites (1-OHP and Σ OHPHE) in urine.

  • 22% of bitumen-exposed non-smokers had 1-OHP-

concentrations above the 95th percentile in German men.

  • The concentrations of the PAH metabolites were much lower

in bitumen-exposed workers than in “typical” PAH settings such as coke-oven works.

  • Smoking is an important predictor of the metabolite

concentrations in urine.

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SLIDE 9

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Lung function

height weight

Calculation of the BMI index

Key-variables:

  • FVC [% predicted]
  • FEV1 [% predicted]
  • FEV1 % /FVC [%]
  • MEF 50 % [predicted]
  • Maximum vital capacity [L] (VCmax)

According to the ATS guidelines 18 / 41 50 100 150 200

Non-smoker Smoker Reference group Reference group Exposed workers Exposed workers

55 109 61 190 51 112 59 191 = N

pre shift post shift FEV1 [% predicted]

Lung function: FEV1 % predicted

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SLIDE 10

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Lung function measurements (Summary)

  • There are unremarkable lung function results (generally

better than the predicted values; “healthy workers”).

  • Only weak influence of the bitumen exposure during the

shift can be observed.

  • Overall, only weak effects on lung function parameters

are detectable.

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Upper airways

NALF analysis (Summary)

  • No significant differences between bitumen-exposed

workers and the reference group could be observed on the upper airways using NALF analysis.

  • No significant shift-effects could be observed on the

upper airways using NALF analysis.

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SLIDE 11

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Irritative effects at the lower airways -Induced sputum-

→ Cellular profile

  • Total cell count
  • Macrophages
  • Neutrophiles
  • Lymphocytes
  • Eosinophiles
  • Epithelial cells
  • IL-5 [pg/ml]
  • IL-6 [pg/ml]
  • IL-8 [pg/ml]
  • NO Derivates (Nitrat/Nitrit) [µM]
  • IL-1β [pg/ml]
  • TNF-α [pg/ml]
  • LTB4 [pg/ml]
  • Protein content [µg/ml]
  • MMP-9 [ng/ml]

→ Soluble (inflammatory) Mediators

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Sputum: IL-8 concentrations

pre shift post shift Non-smoker Smoker Reference group Reference group Exposed workers Exposed workers 1 10 100 1000 10000 100000 1000000 10000000 IL-8 [pg/mL]

(N=57) (N=121) (N=61) (N=199)

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SLIDE 12

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Induced sputum: IL-8 concentrations*

1000 2000 3000 4000 5000

pre shift post shift

p<0.0001 p<0.0001

Time of measurement IL-8 [pg/mL]

Reference group (n=118) Exposed (N=320)

*Adjusted for smoking and other factors 24 / 41

Conclusion from biomarkers of inflammation

Smoking was confirmed as factor affecting inflammatory

marker concentrations in induced sputum samples.

Inflammatory sputum markers were higher before and

after shift in bitumen-exposed workers. This may indicate effects due to repeated exposure.

No dose-dependent association with bitumen exposure

could be observed. A single shift measurement of bitumen is not sufficient to serve as proxy for an average or lifetime exposure.

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SLIDE 13

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Genotoxic risk assessment in bitumen exposed workers:

8-OxodGuo (8-oxo-7,8-dihydro-2‘-deoxyguanosin)

adducts in white blood cells (biomarker of oxidative DNA damage)

anti-BPDE ((+)-anti-Benzo[a]pyren-7,8-diol-9,10-

epoxid)-DNA adducts in white blood cells (biomarker

  • f exposure to B[a]P)

DNA single and double strand breaks and alkali-labile

sites in lymphocytes (alkaline version of Comet assay)

Chromosomal breaks and losses (micronucleus

assay)

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Genotoxic effects I

The genotoxic effects were examined in the blood. Increased 8-oxodGuo-adduct rates and DNA-

strand break-frequencies were detected in the group

  • f bitumen-exposed workers pre and post shift:

indication for (sub)chronic effects.

A dose-response-relationship for bitumen-

exposure during a shift could not be found.

In bitumen-exposed workers specific DNA adducts of

PAH-exposure (anti-BPDE) were not increased.

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SLIDE 14

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The micronucleus assay detects chromosomal

breaks and -losses in vivo. In our study a mutagenic potential of vapours and aerosols of bitumen was not detected.

A dose-response relationship can also not derived

between bitumen exposure and the micronucleus frequencies.

The age is detectable as the most prominent

influencing factor. This is known from the literature and confirms the plausibility of the test results.

Genotoxic effects II

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Conclusions from the Human Bitumen Study

  • In the lower airways inflammatory effects could be

detected in the bitumen-exposed group.

  • There was no dose-response relation for all measured

effect markers with bitumen exposure during a single shift.

  • The cross-shift design revealed increased levels of

inflammatory (pre-clinical?) markers already before shift. This may indicate effects due to repeated exposure.

  • A single shift measurement of exposure is not sufficient to

assess long-term exposure.

  • Assessment of lifetime exposure is impaired by frequent

changes of construction sites. Workers are not aware of accidental higher PAH exposure (“Schwelm Group”).

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SLIDE 15

29 / 41 To all participants of the study To the team of the Human Bitumen Study

The Human Bitumen Study was supported by:

Deutsche Gesetzliche Unfallversicherung (DGUV) Eurobitume Deutscher Asphaltverband e.V. Concawe Zentralverband des Deutschen Dachdecker-

handwerks

Industrieverband Bitumen-, Dach- und

Dichtungsbahnen e.V.

Steinbruch-Berufsgenossenschaft Aksys Ltd.

Thanks for your attention!!

Many thanks!