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Security Scanners

1. Introduction

    The SCENIHR opinion states:

    1. BACKGROUND

    The possibility of introducing security scanners on the list of eligible screening methods and technologies for screening persons was first proposed to the Council and the European Parliament on 5 September 2008 on the basis of the positive vote of the Member States' aviation security experts.

    On 23 October 2008, the European Parliament adopted a resolution on the impact of aviation security measures and security scanners on human rights, privacy, personal dignity and data protection, requesting a more in-depth assessment of the situation, opposing the Commission's proposal. The Commission agreed to review these matters further and withdrew security scanners from its original legislative proposal. The draft legislation became Commission Regulation (EC) No 272/2009 to apply as of 29 April 2010.

    The Commission consulted with all parties concerned and issued a first analysis on the use of security scanners: the Communication to the European Parliament and the Council on the use of security scanners at EU airports of 15 June 2010. Following this Communication an in-depth impact assessment was carried out by the Commission. It concluded that security scanners are an effective method for the screening of passengers and should be authorised for use at EU airports under certain operational conditions and detection performance standards. The report also identified the need to avoid any risks to human health and to ensure the protection of fundamental rights.

    Consequently, the Commission proposed to add security scanners to the list of the methods for the screening of passengers and linked their use to a number of conditions. On 10 and 11 November 2011 the Commission adopted this legislation. The relevant elements of the package are contained in Regulations 1141/2011 and 1147/2011. In particular, under the new legislation security scanners are not mandatory for Member States and/or airports and can only be used at EU airports in accordance with minimum conditions such as: security scanners shall not store, retain, copy, print or retrieve images; any unauthorised access and use of the image is prohibited and shall be prevented; the human reviewer analysing the image shall be in a separate location and the image shall not be linked to the screened person and others. Passengers must be informed about the conditions under which the security scanner control takes place. In addition, passengers are given the right to opt out of a control with scanners and be subject to an alternative method of screening.

    In order to safeguard citizens' health and safety, at this stage, the Commission has allowed Member States and/or airports to deploy only security scanners which do not use ionising radiation.

    The methods currently allowed for passenger screening are laid down in point 1 of part A of the Annex to Commission Regulation (EC) No 272/2009 and are as follows:

    1. Hand search;
    2. Walk-through metal detection (WTMD) equipment;
    3. Hand-held metal detection (HHMD) equipment;
    4. Explosive detection dogs;
    5. Explosive trace detection (ETD); and
    6. Security scanners which do not use ionising radiation.

    Commission Regulation (EU) No 185/2010 of 4 March 2010 lays down detailed measures for the implementation of the common basic standards on aviation security. Point 4.1.1.2 of the Annex determines that passengers can be screened by a hand search or by a walk-through metal detector. Additional requirements on combining different methods in order to achieve effective detection are included in EU security restricted legislation.

    In the EU, some countries tested security scanners and have now introduced security scanners under the new rules. In the current international context, security scanners are being deployed at airports worldwide, especially in the USA where several hundred security scanners are currently in use. Russia has been using security scanners at airports since 2008 and will continue to deploy them more widely in the future. Other countries are either planning (e.g. Canada, Australia) or examining the possibility of introducing security scanners (e.g. Japan).

    Four main security scanner technologies for passenger screening are currently on the market but this does not preclude other technologies from appearing:

    Security Scanner Technologies

    Body scanning security technology Type of energy used and level of exposure
    Passive millimetre-wave No radiation emitted
    Active millimetre-wave Non-ionising radiation (24-30 GHz range), 60 to 640 μW/m2
    X-ray backscatter Ionising X-ray radiation between 0.02 and 0.1 μSv per screening
    X-ray transmission imaging Ionising X-ray radiation between 0.1-5 μSv per screening

    While X-ray based security scanners are currently used in the USA and as a trial in one UK airport, several Member States (e.g. Italy, France, Germany and Austria) prohibit the use of ionising radiation for non-medical purposes.

    The protection of workers and the general public from ionising radiation is regulated under Directive 96/29/EURATOM. Article 6 of this Directive specifies the basic principles of radiation protection, among them that "Member States shall ensure that all new classes or types of practice resulting in exposure to ionising radiation are justified in advance of being first adopted or first approved by their economic, social or other benefits in relation to the health detriment they may cause." According to the Directive, the uses of X-ray security scanners are notified to the National Competent Authorities (Art. 3) and an authorization shall be required by the Member States (Art. 4). The Directive also sets cumulative dose limits for workers (Art.9) and for members of the public (Art. 13).

    As indicated in the recently adopted legislation on security scanners, the Commission would like to receive information on the impact on human health of the technologies available on the market and in particular on the X-ray based security scanner technologies.

    2. TERMS OF REFERENCE

    The SCENIHR is asked:

    1. To assess the potential health effects related to the use of all types of security scanners used for passenger screening which emit ionising radiation.

    2. If any effects are identified under 1, to quantify the risks and, if feasible, to estimate the additional number of cases of diseases that are expected to occur in Europe due to the use of this technology at EU airports, differentiating between the general public and exposed workers as indicated below.

    In its assessment, the SCENIHR is asked to consider in particular the risk for populations that are regularly exposed to such technologies (e.g. frequent flyers (to be defined), air crew, security workers operating the scanners and other airport staff) and potentially vulnerable groups (e.g. pregnant women, children).

    The SCENIHR should compare the relative risk of such security scanners using X-ray based technologies to other security scanner technologies on the market.

    As health protection against ionising radiation falls under the provisions of the Euratom Treaty, the SCENIHR is asked to consult in its assessment the Group of Scientific Experts referred to in Article 31 of the Euratom Treaty (Art. 31 GoE), advising the Commission on radiation protection matters.

    3. SCIENTIFIC RATIONALE

    3.1 Introduction and scope

    To assess the potential harm, considering the link between radiation exposure and health risks, we need to estimate the amount of exposure of the various exposed groups due to the use of security scanners for passenger screening. As specified in the Terms of Reference (section 2.), this opinion considers only the use of security scanners using X-ray technology at EU airports and deals only with radiation detriment. Justification of practices using ionising radiation as required by radiation protection legislation is beyond the remit of this opinion.

    Ionising radiation is ubiquitous and everyone is continuously exposed to it. All Europeans receive on average 1 mSv annually from background radiation from naturally occurring radionuclides in the ground and within the body. Another component of natural radiation is cosmic radiation from space. In addition, we are exposed to indoor radon through inhalation to a widely varying extent (range 0.1-10 mSv). The predominant man-made sources of radiation are medical, diagnostic and therapeutic applications with a wide range of doses resulting in a contribution of between approximately 20 and 50% of the collective dose to the population in the EU. The collective dose is computed from the product of the irradiated population and the average effective dose per person. The average effective dose per person due to diagnostic medical exposures has been estimated as 0.3-0.4 mSv in the UK and 1.8-2.5 mSv in Germany, while the average effective dose per person due to natural sources varies within Europe (as described above) with a median of about 2 mSv. The population average doses from therapeutic applications have not been determined because they only affect a small number of people, even if these people receive very high doses. (REF SPIE paper)

    At exposure levels above hundreds of mSv, adverse health effects of ionising radiation have been well established. The current model for estimating risk of low dose ionising radiation (commonly defined as approximately 100 mSv) is based on linear extrapolation from experimental and epidemiological data obtained at higher doses. The assumptions concerning the shape of the dose-response curve [Query? – Judy Burns] are crucial for the assessment. A monotonic linear pattern (linear, no-threshold model) is commonly used, which is assumed to represent a prudent choice, because at very low doses and dose rates the effects become indistinguishable from the background. X-radiation is a form of sparsely ionising radiation called low Linear Energy Transfer (LET) radiation. Present estimates of the long-term health effects of radiation exposure, such as cancer risk, are described in the International Commission for Radiation Protection (ICRP) publication 103 and are based largely on the average exposure to a population. Based on the recommendations of the ICRP (ICRP 1998), radiation cancer risks relative to the baseline are judged to be small at low doses up to a few mSv. Cancer risks at effective doses of the order of 1 µSv, such as those encountered in passenger security-scanners using X-rays, are unknown. It is unlikely that epidemiological studies or experimental studies with the present methodologies could, at such low doses, have a sample size large enough to provide sufficient statistical precision and power to distinguish the increment for determining risk estimates. At doses below 50 mSv, epidemiological studies have so far been unable to provide information on the shape of the dose-response curve for cancer risk although some guidance can be obtained from experimental studies at doses above 1 mGy. However, for risk assessment purposes, the ICRP assumes a linear dose-response relationship, with no lower threshold below which radiation would have no detrimental effect.

    Source & ©: , Health effects of security scanners for passenger screening (based on X-ray technology), (2012),
     1. Background, 2. Terms of reference and 3.1 Introduction and scope, pp.10-13