What is an XRF?
XRF (X-ray fluorescence) is a non-destructive analytical technique used to determine the elemental composition of materials.
What do we currently use it for?
The Washington State Department of Health (DOH) purchased an XRF machine and allowed the Health District to borrow it to investigate elevated blood lead for children under 6 years of age. Staff have used this XRF in several lead investigations and have successfully been able to identify lead paint hazards in several homes in the county. Old paint containing lead remains the largest risk of lead exposure. Although the sale and use of lead-based paint was banned in the United States in 1978, older houses may still have traces of lead paint. Paint older than 1978 is of concern but paint older than 1950 may have very high levels of lead. In 1978, the Consumer Products Safety Commission banned the sale of lead-based paint for residential use.
If the paint appears to be in good condition, there is less risk of lead exposure. However, over time, paint can begin to peel, chip, crack, or deteriorate. Lead can also be released from old paint when remodeling is done. Deteriorating or disturbed paint can create dust contamination on the interior of the house and in soils near the perimeter of the house.
What are other possible uses?
SHD staff would continue to use the XRF for home visits for children with elevated blood lead levels. The model that we are currently looking into purchasing would also allow us to check other materials such as soil, metal, plastics, etc.
An additional use would be for school pre-occupancy inspections. Several private schools are located in older buildings that have likely not been screened for lead hazards. The XRF could be used by the school team when performing a site approval.
XRF’s can be programmed with software that allows them to detect other highly toxic elements such as arsenic, cadmium, chromium, copper, mercury, nickel, selenium, silver, vanadium, and zinc so there are many possibilities for expanded use.
Why are we interested in this model?
There are two types of XRF hand-held lead detection devices: those that use radioisotopes and those that use x-ray tubes. Staff would like to purchase an XRF that uses x-ray tubes as they are safer as they do not have a radioactive core. One advantage of the x-ray tube model over the radioisotope device is that as the cadmium radioisotope loses strength, readings take longer. Because the half-life of the cadmium radioisotope is about 15 months, it takes twice as long to get a reading after 15 months, 4 times as long to get a reading after 30 months, and so forth. The cadmium core needs to be replaced frequently in order to get quicker and more accurate results. The machines that DOH use need to have the core replaced around every 15 months at a cost of $7-10k each time.
The radioisotope device requires special licensing and may pose travel issues. In addition, when a radioisotope device reaches the end of its service life or is broken or damaged, it must be disposed of as hazardous material.
Staff recommend purchasing the Bruker Titan XRF machine. Cost is approximately $31,420 and includes the machine and two hours of training by the vendor. If approved, the machine would be paid for with general funds.