ART in the context of tiered approaches for Exposure Assessment and Chemical Safety Assessment

Cefic LRI workshop Advanced REACH Tool (ART), 20 April 2012

Dook Noij, Dow Benelux

Risk assessment under REACH: requirements

To meet the 2010 REACH deadline industry has registered approximately 1500 classified substances (which require a risk assessment)

Assuming on average 10 uses/ES’s per substance and 10 contributing scenarios per ES, this amounts to at least 150,000 assessments in the first registration period

To achieve this, industry needed assessment tools that:• facilitate mass processing of ES risk assessments with

‘sufficient’ conservatism and ‘acceptable’ uncertainty• enable a tiered risk assessment approach

2

Tiered approach

3

Tier 1

tools

Con

serv

atis

m

UncertaintyLow High

Hig

h

Specific models and/or

measurements

Tier 2

tools

• Preferably addressing inhalatory AND dermal exposure• Conservative in nature• Screening tool, targeting for use of higher tier tools• Broad range of application in many type of working environments• Transparant, relatively easy to use, enable efficient processing• Clear description of boundaries

• More complex models, require expertise in use• More accurate exposure estimates• Improved confidence in exposure predictions• Range of application as broad as possible (dependent on range of calibration data)• Clear description of boundaries

StoffenmanagerRisk of DermDREAM

ARTMEASEBEAT

Tier 1 ½

tools

ECETOC TRAEMKG

Observation: tools used in REACH assessments

Tier 1 tools:• ECETOC TRA tool v2• Both for inhalatory and dermal exposure• Used in approx. 90 – 95 % of the registrations• Further improved version 3 released this monthTier 1½ tools:• Stoffenmanager (inhalatory exposure)• Risk of Derm (dermal exposure)Tier 2 tools:• ART (inhalatory exposure)• PESToolSector Specific Tools :• ECPA OWB tool• MEASE

4

Advanced REACH Tool (ART)

5

Core: calibrated mechanistic model

Advanced REACH Tool (ART)

6

Full model including Bayesian module

Position of ART in exposure assessment

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• Clearly developed for application in REACH risk assessment

• Contributes to filling the gap for Tier 2 assessment tools

• Application in REACH risk assessments will be focussed on Tier 2 assessments, where Tier 1 is failing

• May have wider application (however not (yet) ready for application in CAD exposure assessments)

ART: strengths

• Good conceptual basis (source – receptor model)

• Calibrated with fairly large number of good quality data

• Modifying factor categories and corresponding multipliers well defined with good justification for numerical values

• Flexibility in setting options for exposure predictions

• Improved confidence in exposure predictions

• Further reduction of uncertainty in the exposure predictions (provided the added data are representative for the scenario assessed……..)

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ART: limitations

• Reliability of predictions in domains where hardly any measurement data are available for calibration may still be low

• Imprecision can be improved by reducing inter-rater variability; predictions may vary 2-3 orders of magnitude depending on the rater; this can be improved by means of guidance, training and experience

• Despite large number of calibration data, accuracy can be fairly low; larger calibration dataset(s), covering more sectors and activity types, are needed to improve accuracy

• ART developers can be more explicit on the boundaries of the tool

9

Accuracy for liquids and dusts

10

Variance explained: 66 % Variance explained: 50 %

2-3 orders of magnitude between estimated (ART) and measured exposure

How to align ART with industry’s needs (1)

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• Tielemans et al (2011): ‘ART will be further refined in the future and should therefore be considered an evolving system.’Changing the model or the calibration factors within the model during the time period industry is working on REACH assessments is not acceptable. This would mean that the assessments as documented in CSR’s, can not be reproduced, when needed.The only option for doing this, is maintaining several versions of the ART tool simultaneously

• How will ART account for changes in prediction over time due to updates/additions in the database used as input for the Bayesian module?

• REACH worker risk assessments are aligned to Process Categories (PROC: ECHA Use Descriptor System); application and reproducibility of the tool would benefit from development of prepopulated (default) scenarios for PROC’s

How to align ART with industry’s needs (2)

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• Application of modifying factors in the assessment implicates Operational Conditions and Risk Management Measures that not only have to be documented in the CSR, but also have to be communicated in the extended SDS. Development of standard text/phrases that are aligned to the ART modifying factors and can be applied in SDS systems would greatly support industry’s needs

• It will be very difficult to do scaling on exposure scenarios assessed with ART. Nevertheless it is communicated that scaling with ART is possible. Assuming this is true, the developers should clearly explain and document how scaling can be applied and what the boundaries are of scaling with ART

Enjoy your ART workshop !!!

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