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Lead is a heavy metal with many uses, including in some old paints. Ingestion of particles or inhalation of dust from degraded paint, particularly by children, may cause lead poisoning. The French Public Health Code plans for the detection of lead in paint as part of a real estate (CSTB - Centre Scientifique et Technique du Bâtiment) property analysis.

In 2004, Afsset also worked in partnership with the CSTB on a study of the assessment of performances of different portable devices for detecting lead in layers of old paint. The test results showed that the devices studied present limitations and do not always detect or may underestimate the result. This work featured in a report published in 2005.

The French Environmental Health Safety Agency (Afsse) received a solicited request on 16 February 2004 from the French Ministries of Health and the Environment, asking the Agency to assess the reliability of devices for detecting lead in old paint (tube and source devices), following a study report produced by LNE (Laboratoire National d'essais) on the different types of devices currently on the market. This lead measurement is provided for by the French Public Health Code for real estate transactions of old properties, particularly to prevent lead poisoning, and is currently being extended to property rentals.

Working method:

To answer this solicited request, Afsse asked the CSTB to lead a working group composed of representatives of different scientific and technical bodies specialising in the subject, such as the CSTB, LNE and Paris Hygiene Laboratory (LHVP), and various experts with recognised skills.

General points & contextual elements:

Looking for lead requires the use of X-ray fluorescence equipment, which is divided into two categories; radioactive source equipment and more recent equipment fitted with an X-ray tube. The results of these tests showed that X-ray tube equipment does not detect lead paint if it is under a thick plastic cover, and in one case if it is of them under significant layers of paint. Moreover, measurements with this equipment level off of limit at a concentration between 6 and 10 mg/cm2. Source equipment presents different types of limits; two devices do not detect lead paint under a thick plastic cover either, and the third considerably underestimates the result.

In view of these results, Afsse was asked to state if equipment fitted with an X-ray tube could be used to detect lead in paint in the framework of expert assessments for the prevention of lead poisoning in homes, and as part of risk analyses of lead accessibility. Afsset was also asked to propose criteria with which all marketed X-ray fluorescence equipment should comply, which may be integrated into the regulations.

The working group noted that the LNE study was conducted in laboratory conditions for certain typical situations, and certain levels of lead concentrations in reference materials. But the distributions of the results of measurements in actual situations are unknown. The objective must be to enable an estimate of the overall expected number of false negatives per type of equipment used and to set an acceptable limit value in public health terms which itself will set limits for use of different equipment types. For this, the typical situations encountered in the field and their relative frequencies need to be known.




The working group studied the results of the measurements carried out by the LHVP in housing when lead poisoning had occurred, using source equipment, and the results of comparative measurements taken in the field by "Habitat santé développement". In 60% of cases, surfaces containing lead salts would not be identified with tube equipment. The results obtained with different X-ray tubes cannot be superposed either.

The working group suggested taking additional measurements, in accordance with a flawless protocol and experiment plan in a residence that is currently being renovated. These measurements were carried out on 10 December 2004 using a source detector and a tube detector, and were accompanied with physico-chemical measurements conducted at LNE.




A working group report, conducted jointly by the CSTB and Afsse laying down recommendations for the use of these lead detectors on paint, was issued on 11 May 2005.

Following this report, Afsse issued an opinion on 23 May 2005.

Given the results of different tests, the expert group found that no device tested for lead detection by X-ray fluorescence produced 100% reliable results, but that of all the devices currently available on the market, those detecting lead by L line and K line gave the most realistic results. On this basis, Afsse noted in its opinion that, of the devices currently available, those detecting lead by L line only did not guarantee reliable results.

However, it is possible that these tube devices can improve and be capable of producing reliable results. This is why Afsse, in its opinion, estimated that, given the uncertainties over the measurements observed with all types of available device, criteria for the minimum performances to be achieved should be established for all lead detection equipment by X-ray fluorescence, based on the ability to measure sets of reference test pieces and on the application of a technical guide defining the conditions for using these devices. Moreover, it appeared essential to set up an equipment approval procedure before marketing, together with regular technical inspections ensuring that the equipment performances are maintained.

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