Easy lead-screening kits for use in field.

Before engaging a laboratory to test for lead in water - or breaking out the state-of-the-art XRF computerized lead-testing instrument with a technician attached - you may want to consider using a few inexpensive field screening tests to decide if the heavy guns are really needed. Although these kits do not provide quantitative analysis, they will tell you if lead is present.

A word of caution: The kits are for screening only and are best used to rule out contamination. Obviously, if lead is found in the samples, further analysis is necessary.

Several of the test kits on the market are quite good and are relatively inexpensive. Of these, we find four to be particularly useful: Lead CheckTM from BGI, Inc., and Know Lead[TM] from Carolina Environment, Inc., for surface analysis; Lead Alert[TM] from Pace Environs, Inc., for testing friable materials; and CHEMetrics' Lead Test for testing water. These kits are all available either through catalog sales or from safety supply dealers.

We have found the Lead Check kit to be the simplest and most frequently used. Swabs on the ends of small cardboard tubes contain ampules of reagents. The reagents are released and mixed when the tube is pinched as shown on the instructions and shaken. Then you rub the wet swab on any hard surface. If the swab turns pink, lead is present. Simple. Depending on the supplier, each test costs about $2.

The Know Lead kit is also designed for detecting lead on surfaces. It too has a test dauber - with a difference. The Know Lead is the only kit we are aware of that uses a dry chemical in the dauber. The greatest advantage of this feature is the kit's shelf life of four-plus years. The dauber is activated by being placed in water and, when it is wet, being rubbed on any hard surface. The manufacturer claims that the kit is sensitive at the action level for lead ([less than]600 ppm). The instructions are easy to follow and comprehensive. At about $4 per test, this kit is well worth the price.

For soil, dust, paint chips, or any friable material, the Lead Alert is our test kit of choice. The kit contains 40 tests, each consisting of abrasive strips and a coring tool to get through layers of paint; leadfree collection swabs and adhesive collection papers; plastic vials and plastic rods to grind the sample; leaching solution; test cards; and positive-control test strips. Although the Lead Alert test is not the simplest to use, it is the most versatile. Also, it has the most comprehensive and clearly written instruction booklet of any test kit that we regularly use. Although Lead Alert is a bit more expensive than the other kits, its versatility makes up for the difference.

CHEMetrics has made its mark on our industry by making colorimetric analysis of water quite easy. They package their reagents in unit-dose glass ampules. The CHEMetrics Lead Test takes advantage of this technology and is an advance in the dithizone method for determining trace levels of lead in drinking water. Increased dithizone stability, the convenience of a prepackaged reagent in a unit-dose form, no need for special glassware, and a sensitivity range of 0 to 50 ppb (measured in micrograms per liter) all make this kit a particularly attractive screening tool for field use. On the down side, the instructions are Spartan, and it takes a trial or two to get used to the methodology. Once mastered, however, the test is fast, easy, and inexpensive compared with lab analysis.

Buyer Beware

We recently saw an ad for an indoor air quality test for schools. The price of the kit, with analysis, is $250. The producer admonishes the buyer that the kit is for screening only - it is not a diagnostic tool. This makes the kit one of the most expensive screening devices on the market - and probably the most limited. Your sanitarian's skills, including administrative, observational, and problem-solving skills, are far more cost-effective than an expensive kit that provides little useful information.

The kit consists of two passive monitors - one for VOCs, the other for formaldehyde - and a sticky tape to take a surface mold sample. Passive samplers are best used in an industrial hygiene setting and are designed for that purpose. The exposure limits for schoolchildren, among whom there may be atopic individuals, are quite different from those in an industrial setting. The field accuracy of passive samplers is influenced by the inherent random error of the monitor's placement and the limits of its detection and quantitation capabilities. Generally, passive dosimeters are accurate within [+ or -] 25 percent of airborne concentrations, depending on temperature and humidity. If the monitoring is performed by untrained personnel, the accuracy could be off by as much as 50 percent. A thorough inspection of the facilities would reveal possible culprits of off-gassing. If tests are necessary to prove a point, a professional industrial hygienist with proper instrumentation would be the most cost-effective strategy.

If you see mold, it is most likely due to a problem with moisture. A good building inspector would probably be the best ally in finding the source of the problem. If you need to identify the mold, collect the sample using a piece of transparent tape. Simply press the tape against the moldy spot, and place the tape, sticky side down, on a microscope slide. To identify the mold, invert the slide and view it under a high-power microscope, or let a public health microbiologist read it for you. Once the mold is identified, the structural or operational problem still needs correction.

Kits like this may have value for a homeowner, whose resources and skills are limited. It has little place, however, in good environmental health practice and is best avoided.