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Title: New motorway projects and proximity air pollution : Evaluation of sanitary risks using inhalation an


1
New motorway projects and proximity air pollution
Evaluation of sanitary risks using inhalation
and ingestion vectors
  • Christelle Bassi
  • Stella Becker
  • Laurence Calovi

2
Sanitary Risk Evaluation as a tool of the
decision making process
  • Frequent exceeding of regulatory air pollution
    thresholds,
  • Solutions to improve air quality in urban areas
    needed,
  • In current conditions no projects are acceptable.
  • Law
  • Evaluation of the net contribution of the project
    to air and soil pollution, and to health effects,
  • Positive impacts on health taken into account,
  • Lot of uncertainties,
  • Bypass are not the best way in all cases.

3
The five steps of Sanitary Risk Evaluation
Identification of the hazard
?
Risk characterization
Relationship between dose and response
Uncertainties analysis and discussion
?
?
?
Evaluation of exposure scenario
?
4
Identification of the hazard
?
  • Inventory of
  • hazardous agents emitted by the road,
  • agents noxious effects,
  • contact modes.
  • Choice of a risk tracer agent
  • in each chemical family
  • for each induced health effect (carcinogenic and
    non)

5
Relationship between dose and response2 types
of effects, 2 methods
?
  • Agents acting with a threshold effect
  • Heath effects are proportional to the exposure or
    the dose
  • search of the no effects dose
  • Agents acting without threshold effect
  • The probability of occurrence of heath effects is
    proportional to the dose
  • search for the dose corresponding
    to an acceptable risk
  • Choice of a toxicological reference value

6
Evaluation of exposure scenario
?
  • Evaluation of the population exposed,
  • Determination of exposure vectors (inhalation,
    ingestion, skin contact)
  • For each exposure vector considered, the
    evaluation consists in quantifying
  • frequency,
  • duration,
  • intensity of exposure

7
Risk CharacterizationApplying a dose-response
relationship to an exposure scenario
?
  • Non carcinogenic effects and acute toxicity
  • The potential occurrence of an effect in a
    population is evaluated through the calculation
    of a hazard ratio (HR).
  • HR DEC/TRV
  • DEC Daily exposure concentration
  • TRV Toxicological reference value
  • If HR 1 exposed population is theoretically
    preserved from undesirable effects appearance on
    human health
  • If HR gt 1 toxic effect may appear
  • Qualitative method which do not express a
    quantified risk

8
Risk CharacterizationApplying a dose-response
relationship to an exposure scenario
?
  • Carcinogenic effects (without threshold effect)
  • The individual risk excess (IRE) and the number
    of cases in excess (NCE) among the exposed
    population are calculated and compared to an
    acceptable risk limit.
  • IRE DED?TRV
  • DED Daily exposure concentration (mg/m3 or
    µg/m3).
  • DED Inhalation Cp?F ?(T/Tm),
  • DED Ingestion Ci ?Qj ?(F/P) ?(T/Tm)

9
Risk CharacterizationApplying a dose-response
relationship to an exposure scenario
?
  • Carcinogenic effects (without threshold effect)
  • NCE S ERI ?Pop
  • NCE number of cases in excess
  • Pop population in the unit cell of the grid used
    for modeling pollutants concentrations in the
    air.
  • Acceptability threshold
  • 10-6 acceptable risk in a general population
    (USA, Canada),
  • 10-5 Intervention limit for polluted soil
    (Directive of the French Ministry of Environment,
    OMS),
  • 10-4 acceptable limit in professional
    environment.

10
Uncertainties analysis and discussion
?
  • The analysis of uncertainties is the synthesis of
    all lacks of knowledge that required making
    hypothesis and assumptions.
  • Discussing clearly all these uncertainty elements
    allows to evaluate the accuracy of the SRE and to
    draw recommendations.
  • Uncertainty elements are classified according to
    the way they influence risks evaluation
    over-estimation, under-estimation or with unknown
    effect.

11
2 pilot studies performed in France
GCO bypass
  • Ingestion vector

L2 north bypass
  • Inhalation vector

12
L2 northern bypass of MarseilleSRE Inhalation
vector
  • Length 3.5 km,
  • traffic 120,000 vehicles/day,
  • population 700,000 pers.,
  • underground over most of its path (cut and cover
    technique),
  • very frequent exceeding of regulatory pollution
    thresholds,
  • various acute sanitary effects recorded.

13
Results of SRE of northern bypass of Marseille
14
L2 north discussion of uncertainties
  • Risks under-estimation factors
  • only the inhalation vector is considered,
  • lack of information about air pollution
    deposition modeling impossible.
  • selection of pollutants among all that are
    potentially emitted
  • neglecting secondary pollutants, like ozone,
  • toxicological reference value not known for CH4
    or N2O.
  • Risks over-estimation factors
  • Exposure frequencies 24h/24h exposure. For
    people living in the study area but working
    outside, and vice versa, it leads to an
    over-estimation,
  • background pollution concentrations were supposed
    constant until 2020,
  • Unknown effect
  • The population is supposed to remain constant
    from 1999 to 2020,
  • in-chain use of various models for traffic,
    emissions and dispersion

15
GCO Western bypass of Strasbourg SRE Ingestion
vector
  • Length 28 km,
  • traffic 40,000 vehicles/day (15 trucks),
  • population 450,000 pers.,
  • Crosses rural zones
  • Air pollution peaks and acute sanitary effects by
    inhalation are frequent.

16
Results of SRE of Western bypass of Strasbourg
17
GCO discussion of uncertainties
  • Risks under-estimation factors
  • No ingestion of water,
  • No outside contributions for food contamination,
  • No integration of ubiquitous concentrations in
    plants.
  • Pollutants related with the equipments of the
    infrastructure and vehicles not taken into
    account (tires, brakes, rails, roads)
  • Risks over-estimation factors
  • Maximum exposure frequency,
  • No washing of fruits and vegetables,
  • Cattle fed exclusively fodder grown in the study
    strip,
  • Milk and meat from the same contaminated herd,
  • Distribution in PAH the risk /7 if the BaP
    represents 1 of PAHs,
  • No phenomena of reduction of the i pollutant in
    the plant and soil,
  • Pollutant remains in its primary form,
  • Air background noise values constant between
    2003 and 2020,
  • Highest protection TRV
  • Unknown effect
  • Soil background noise constant between 2003
    and 2020 (farming habits, accumulation of
    industrial facilities),
  • use of factors for transferring of pollutants to
    the soil and food,
  • No summing of the risks by ingestion and
    inhalation,

18
Further developments
  • Summaries of both studies are in progress,
  • Summaries have to go through the review of all
    French Ministries (including Health Ministry),
  • Information to the public,
  • Air methodology in progress,
  • Soil methodology launched,
  • Water methodology coming soon.

19
More information ?
  • Christelle Bassi
  • christelle.bassi_at_equipement.gouv.fr
  • Stella Becker
  • stella.becker_at_equipement.gouv.fr
  • Laurence Calovi
  • laurence.calovi_at_equipement.gouv.fr
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