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Setting occupational exposure limits: Practices and outcomes of toxicological risk assessment
Södertörn University, School of Life Sciences. KTH, Filosofi.ORCID iD: 0000-0003-3799-4814
2011 (English)Doctoral thesis, comprehensive summary (Other academic)Text
Abstract [en]

Occupational Exposure Limits (OELs) are used as an important regulatory instrument to protect workers’ health from adverse effects of chemical exposures. The main objective of this thesis is to study risk assessment practices in the setting of OEL in order to produce knowledge that will help improve the consistency and transparency of OELs.

For the purpose of paper I a database of OELs for a total of 1341 substances was compiled. Of these, only 25 substances have OELs from all 18 included organisations while more than one third of the substances are only regulated by one organisation alone. The average level of OELs differs substantially between organisations; the US OSHA exposure limits are (on average) nearly 40 % higher than those of Poland.

In paper II six EU member states’ OELs are compared to the European Commission’s OELs. Also within Europe there is a large difference concerning the average level of OELs (35%). The average level of lists tends to decrease over time, although there are exceptions to this. There are also indications that the exposure limits of EU member states are converging towards the European Commission’s OELs.

The work presented in paper III identifies steps in the risk assessment that could account for the large differences in OELs for 14 different substances. Differences in the identification of the critical effect could explain the different level of the OELs for half of the substances. But the age of the data review could not account for all the differences in data selection, only one fifth of the documents referred to all available key studies. Also the evaluation of the key studies varied significantly.

The aim of paper IV was to investigate how the Scientific Committee on Occupational Exposure Limits (SCOEL) of the European Commission uses assessment factors when proposing health-based indicative OELs. For only one third of the investigated OELs were explicit assessment factors given. On average the safety margin of the recommendations was 2.1 higher when an explicit assessment factor had been used. It is recommended that the SCOEL develop and adhere to a more articulate framework on the use of assessment factors.

Paper V focuses on the Derived No-Effect Levels (DNELs) which are to be calculated under the new European Union REACH legislation. It is a comparison of the safety margins of 88 SCOEL recommendations with those of the corresponding worker-DNELs, derived according to the default approach as described in the REACH guidance document. Overall, the REACH safety margins were approximately six times higher than those derived from the SCOEL documentations but varied widely with REACH/SCOEL safety margin ratios ranging by two orders of magnitude, from 0.3 to 58.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology , 2011. , viii, 40 p.
Series
Theses in Risk and Safety from the Division of Philosophy at the Royal Institute of Technology, ISSN 1654-627X ; 6
Keyword [en]
Assessment Factor, DNEL, Euroepan Union, Occupational Exposure Limit, REACH, Risk Assessment, Regulatory Toxicology, SCOEL, Uncertainty Factor
National Category
Pharmacology and Toxicology
Identifiers
URN: urn:nbn:se:sh:diva-29722ISBN: 978-91-7415-853-3OAI: oai:DiVA.org:sh-29722DiVA: diva2:911680
Public defence
2011-02-28, F3, Lindstedtsvägen 26, Stockholm, 09:30 (English)
Opponent
Supervisors
Available from: 2016-03-14 Created: 2016-03-14 Last updated: 2016-03-14Bibliographically approved
List of papers
1. Occupational exposure limits: A comparative study
Open this publication in new window or tab >>Occupational exposure limits: A comparative study
2008 (English)In: Regulatory toxicology and pharmacology, ISSN 0273-2300, E-ISSN 1096-0295, Vol. 50, no 2, 261-270 p.Article in journal (Refereed) Published
Abstract [en]

Occupational exposure limits (OELs) are used as an important regulatory instrument to protect workers' health from adverse effects of chemical exposures. The OELs mirror the outcome of the risk assessment and risk management performed by the standard setting actor. In this study we compared the OELs established by 18 different organisations or national regulatory agencies. The OELs were compared with respect to: (1) what chemicals have been selected and (2) the average level of exposure limits for all chemicals. Our database contains OELs for a total of 1341 substances; of these 25 substances have OELs from all 18 organisations while more than one-third of the substances are only regulated by one organisation. The average level of the exposure limits has declined during the past 10 years for 6 of the 8 organisations in our study for which historical data were available; it has increased for Poland and remained nearly unchanged for Sweden. The average level of OELs differs substantially between organisations; the US OSHA exposure limits are (on average) nearly 40 % higher than those of Poland. The scientific or policy-related motivations for these differences remain to be analysed.

Keyword
Kemikalie reglering, arbetsmiljö, gränsvärden, riskbedömning
National Category
Pharmacology and Toxicology
Identifiers
urn:nbn:se:sh:diva-5731 (URN)10.1016/j.yrtph.2007.12.004 (DOI)000254036000021 ()18226844 (PubMedID)2-s2.0-39149085645 (ScopusID)
Available from: 2011-01-27 Created: 2011-01-27 Last updated: 2016-10-04Bibliographically approved
2. Are occupational exposure limits becoming more alike within the European Union?
Open this publication in new window or tab >>Are occupational exposure limits becoming more alike within the European Union?
2008 (English)In: Journal of Applied Toxicology, ISSN 0260-437X, E-ISSN 1099-1263, Vol. 28, no 7, 858-866 p.Article in journal (Refereed) Published
Abstract [en]

The occupational exposure limits (OELs) established by seven different national regulatory agencies of EU member states are compared with those of the European Commission (EC). The comparison concerned: (1) what chemicals have been selected, (2) the average level of exposure limits for all chemicals, and (3) the similarity between the OELs of different EU member states and the OELs recommended by the European Commission. The average level of the exposure limits has declined during the past 10 years in four of the live countries in our study for which historical data were available to us. Poland has not changed its level noticeably and Germany has increased it. Since the first list of indicative OELs was established by the EC, a few of the EU exposure limits have been lowered. The similarity index indicates that the exposure limits of EU member states are converging towards the European Commission's recommended OELs. Still, the average level of OELs differs between organizations - the Estonian OELs are on average 35% higher than the Polish OELs.

National Category
Pharmacology and Toxicology
Identifiers
urn:nbn:se:sh:diva-5725 (URN)10.1002/jat.1349 (DOI)000260072900005 ()18381691 (PubMedID)2-s2.0-55449123487 (ScopusID)
Funder
The Foundation for Baltic and East European Studies, 988/42/2006:9
Available from: 2011-01-27 Created: 2011-01-27 Last updated: 2016-10-04Bibliographically approved
3. Comparison of Data Used for Setting Occupational Exposure Limits
Open this publication in new window or tab >>Comparison of Data Used for Setting Occupational Exposure Limits
2010 (English)In: International journal of occupational and environmental health, ISSN 1077-3525, E-ISSN 2049-3967, Vol. 16, no 3, 249-262 p.Article in journal (Refereed) Published
Abstract [en]

It has previously been shown that occupational exposure limits (OELs) for the same substance can vary significantly between different standard-setters. The work presented in this paper identifies the steps in the process towards establishing an OEL and how variations in those processes could account for these differences. This study selects for further scrutiny substances for which the level of OELs vary by a factor of 100, focussing on 45 documents concerning 14 substances from eight standard-setters. Several of the OELs studied were more than 20 years old and based on outdated knowledge. Furthermore, different standard-setters sometimes based their OELs on different sets of data, and data availability alone could not explain all differences in the selection of data sets used by standard-setters. While the interpretation of key studies did not differ significantly in standard-setters' documentations, the evaluations of the key studies' quality did. Also, differences concerning the critical effect coincided with differences in the level of OELs for half of the substances.

Keyword
occupational exposure limits, chemicals regulation, regulatory toxicology, risk assessment, risk management
National Category
Production Engineering, Human Work Science and Ergonomics Health Care Service and Management, Health Policy and Services and Health Economy
Identifiers
urn:nbn:se:sh:diva-29723 (URN)10.1179/107735210799160255 (DOI)000280255400001 ()20662417 (PubMedID)2-s2.0-77955678506 (ScopusID)
Funder
The Foundation for Baltic and East European Studies, 988/42/2006:9Helge Ax:son Johnsons stiftelse
Available from: 2011-02-15 Created: 2016-03-14 Last updated: 2016-09-29Bibliographically approved
4. Use of Uncertainty Factors by the SCOEL in their derivation of health-based Occupational Exposure Limits
Open this publication in new window or tab >>Use of Uncertainty Factors by the SCOEL in their derivation of health-based Occupational Exposure Limits
2010 (English)In: Critical reviews in toxicology, ISSN 1040-8444, E-ISSN 1547-6898, Vol. 40, no 9, 791-798 p.Article, review/survey (Refereed) Published
Abstract [en]

The aim of this study was to investigate how the Scientific Committee on Occupational Exposure Limits (SCOEL) of the European Commission uses uncertainty factors when proposing health-based indicative occupational exposure limit values (IOELVs). In total, 75 IOELVs in 62 summary documents published from 1991 to 2003 were analyzed. For 31 of the IOELVs, no explicit uncertainty factor (EUF) was stated. For these, we calculated an implicit safety margin (ISM) as the ratio between the point of departure (POD, derived from the NOAEL or LOAEL of the critical effect) and the proposed IOELV. We further analysed whether date of recommendation, type of critical effect, nature of POD or amount of available data influenced the magnitude of the EUFs and ISMs. The ISMs varied little (range 1-5), while the EUFs showed more variability (range 1-50). The EUFs remained unaffected over time and the ISMs decreased slightly. Significant differences in the magnitude of the EUFs, but not ISMs, were found between critical effects, however, contrary to expected the average EUFs and ISMs for irritation were similar to those for more severe systemic effects. The nature of the POD affected the ISMs and EUFs only slightly and less than expected. Both EUFs and ISMs showed a weak but significant negative correlation with the amount of available toxicological data, measured as the number of relevant publications in PubMed, whereas SCOEL statements on data sufficiency had no influence. Overall, the most striking difference was that between EUFs and ISMs, the former being on average 2.1 times higher.

Keyword
Assessment factor, regulatory toxicology, risk assessment, risk management, safety factor
National Category
Pharmacology and Toxicology
Identifiers
urn:nbn:se:sh:diva-29726 (URN)10.3109/10408444.2010.507628 (DOI)000282087400002 ()20860525 (PubMedID)2-s2.0-77957107850 (ScopusID)
Available from: 2010-11-30 Created: 2016-03-14 Last updated: 2016-03-14Bibliographically approved
5. A quantitative comparison of the safety margins in the European indicative occupational exposure limits and the derived no-effect levels for workers under REACH
Open this publication in new window or tab >>A quantitative comparison of the safety margins in the European indicative occupational exposure limits and the derived no-effect levels for workers under REACH
2011 (English)In: Toxicological Sciences, ISSN 1096-6080, E-ISSN 1096-0929, Vol. 121, no 2, 408-416 p.Article in journal (Refereed) Published
Abstract [en]

The new European Union (EU) REACH legislation requires Derived No-Effect Levels (DNEL) to be calculated for substances produced in quantities above 10 tonnes/year. Meanwhile, the setting of occupational exposure limits (OEL) continues both at the member state and the EU level. According to REACH, Indicative OEL Values (IOELVs) from the Commission may under some circumstances be used as worker-DNELs. On the other hand, worker-DNELs will be derived for several thousand substances, far more than the roughly 100 substances for which IOELVs have been established. Thus, the procedure to set health-based OELs may become influential on that of DNELs and vice versa. In this study, we compare the safety margins of 88 SCOEL recommendations with those of the corresponding worker-DNELs, derived according to the default approach as described in the REACH guidance document. Overall, the REACH safety margins were approximately six times higher than those derived from the SCOEL documentation but varied widely with REACH/SCOEL safety margin ratios ranging by two orders of magnitude, from 0.3 to 58 (n=88). The discrepancies may create confusion in terms of legal compliance, risk management and risk communication. We also found that the REACH guidance document, although encompassing detailed advice on many issues, including default assessment factors for species and route extrapolation, gives no quantitative guidance on when and how to depart from defaults.

Keyword
Chemicals regulation, DNEL, IOELV, Occupational Exposure Limit, REACH, SCOEL.
National Category
Environmental Health and Occupational Health
Identifiers
urn:nbn:se:sh:diva-29725 (URN)10.1093/toxsci/kfr056 (DOI)000290931000018 ()21389111 (PubMedID)2-s2.0-79957844799 (ScopusID)
Note

Som manuskript i avhandling. As manuscript in dissertation.

Available from: 2011-02-15 Created: 2016-03-14 Last updated: 2016-03-14Bibliographically approved

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