The Lead-Based Paint Poison Protection Act (LBPPPA) and the US Consumer Product Safety Commission (CPSC) set the permissible limit for lead in paint manufacturing at 600 parts per million (0.06%) by 1978. Paint manufactured subsequent to this year may contain lead up to this level. Lead-based paint is therefore defined by the LBPPPA and CPSC as any paint containing greater than or equal to 0.06% lead by weight.

The US Environmental Protection Agency (EPA) and the Department of Housing and Urban Development (HUD) define lead-based paint as paint containing lead levels equal to or greater than 1.0 mg/cm² when measured by field XRF analyzers, or 0.5% by weight when analyzed by atomic absorption spectroscopy (AAS). This is nearly 10 times higher than the CPSC definition. The reason for the higher EPA/HUD standard is evidently not based on health issues, but to allow the use of field XRF technology for detecting lead on the site (field analytical methods are discussed elsewhere in these pages).

As the LBPPPA/CPSC definition pertains to paint manufacture, and the EPA/HUD definition governs paint already applied to surfaces, the difference in the definitions does not result in any real-world conflicts.

OSHA Worker Safety Issues

The Occupational Safety and Health Administration (OSHA) does not define lead-based paint, nor does it acknowledge any intinsically safe levels of lead in paint. This situation has resulted in some undesirable consequences.

Painted surfaces that contain lead, but do not meet either definition of lead-based paint, are still governed by OSHA worker protection regulations. These regulations require exposure monitoring, respiratory protection, employee training, and medical monitoring (including blood-tests). General contractors are not ordinarily equipped to comply with the regulation, making it necessary to engage a specialized lead abatement contractor to perform the work.

The two analytical methods acknowledged by EPA and HUD, laboratory AAS and field XRF, have varying levels of sensitivity. Laboratory AAS can detect levels of lead below 0.01%; at this time, field XRF is not capable of analysis at this level. As OSHA does not acknowledge a definition for lead-based paint, it is difficult to assess the minimum sensitivity needed to achieve OSHA compliance.

EPA Requirements

EPA does not require that building owners or occupants undertake any activities with regard to lead-based paints; EPA does require any activities involving the abatement of lead-based paints to be performed by accredited individuals, in accordance with the practices and procedures set forth in their lead regulations (40 CFR 745, Subparts L and Q). The provisions of this regulation begin to take effect in 1998, and achieve full force in 1999.

The US EPA Resource Conservation and Recovery Act (RCRA) regulations set the limit of leachable lead in lead-containing waste at 5.0 mg/L (milligrams per liter). Leachable lead means the amount of lead likely to leach from the waste into the surrounding soil of a landfill. This level is established by an analytical method called the toxicity characteristic leachate procedure (TCLP). Lead containing waste that equals or exceeds the RCRA limit must be transported to a hazardous waste treatment, storage, or disposal facility.

Lead-containing waste shown to have a total lead content below 100 parts per million (0.01%) cannot reach or exceed the EPA RCRA limit for leachable lead, and need not be analyzed by TCLP. Lead containing waste shown to have a total lead content equal to or exceeding 100 ppm may exceed the RCRA standard, and must be analyzed by TCLP prior to disposal.

While EPA does not regard work performed on paint containing less than 0.5% lead to be a lead-based paint activity, the waste from such activities may still be regarded as hazardous under RCRA.

Two field sampling and analysis techniques have been developed for detecting lead in paint. The chemical test kit is designed to be used by the individual home or building owner. The kits detect lead in paint by exposing a sample to a reactive chemical; if the paint contains lead, a color change will be observed. A study conducted be the EPA (A Field Test of Lead-based Paint Testing Technologies: Summary Report, May 1995, EPA 747-R-95-002a) shows that these kits are unreliable, and often fail to detect lead exceeding the "federal threshold" (1.0 mg/cm² or 0.5% by weight), where laboratory analysis has shown it to be present. Moreover, these kits will sometimes indicate the presence of lead above the federal threshold, where laboratory analysis shows much lower levels.

The same EPA study also evaluated the use of field XRF detectors. These instruments detect the presence of lead in paint by channeling a beam of high-energy radiation (x-rays and gamma rays) at the painted surface, and observing the effect. Lead in paint will respond to the stimulus by emitting x-rays - the amount of radiation emitted corresponds to the concentration of lead in the surface. The study concluded that certain types of XRF detectors (those that measure K-shell energy states) are effective (with an error factor of "less than 10%") in detecting levels of lead in paint exceeding the federal threshold, with the following provisos:

• any result of 0.4 to 1.6 mg/cm² is considered inconclusive, and must be confirmed by laboratory analysis,

• correction factors must be applied for various substrates, to account for the interference caused by those substrates.

The advantages of a field XRF are that it can provide results immediately at the site, and does not require intrusive sampling. However, it seems to us that the disadvantages outweigh the advantages:

• Laboratory results can generally be obtained within a day or two of the survey, which is sufficient time for most purposes. Moreover, as laboratory analysis is required for XRF results in the "inconclusive" range, the advantage of the "immediate" result is vitiated.

• In general, bulk sampling of paint films requires much less time on-site than use of a field XRF detector, with a corresponding savings in labor costs.

• Use of a field XRF detector requires substantial overhead in maintenance and the training required to operate the unit.

• Field XRF analyzers lack the sensitivity of laboratory analysis.

In the future, the technology of field testing may improve to the point where such methods are preferable to laboratory analysis. At present, we feel that laboratory analysis is the safest, most accurate, and most cost-effective option available.