• By a certified laboratory.

• By using an onsite instrument operated by trained personnel.

• By using onsite noninstrument-based tests (small kits or handheld devices) at the point of contact with the youth.

Laboratory Testing

Using a laboratory to complete the tests usually requires a contract for services. This demands excellent chain-of-custody procedures because the specimen and the results will leave the juvenile justice agency for processing. The agency and the laboratory should enter into a written contract specifying the laboratory's testing equipment, staff qualifications, chain-of-custody practices, and other procedures. The laboratory should have in place procedures for quality control to ensure the accuracy, validity, precision, performance, and reliability of the tests. Sending specimens to a laboratory will require a longer time to obtain results, but the turnaround time should be limited to 72 hours or less (Crowe and Schaefer, 1992).⁵ Usually a commercial laboratory service will be used, but in some communities, there may be a possibility of obtaining services through a criminal justice or healthcare agency laboratory. Even if an agency plans to do initial testing onsite, a laboratory should be identified and contracted to perform any necessary confirmatory tests.

Onsite Instrument-Based Testing

Testing instruments can be purchased or leased for use at an agency for initial immunoassay tests. These instruments can test for one drug at a time or for a group of drugs. Staff who operate these machines must be trained and must follow the manufacturer's suggested procedures for operation. The instruments must be calibrated regularly as directed by the manufacturer to ensure test accuracy. Policies and procedures should include methods for monitoring each aspect of the testing process to ensure quality control. Further, safety precautions for conducting the tests should be incorporated in agency policies. Results should be available relatively quickly with this type of testing; however, sometimes it is more practical and cost effective to run tests only when there are enough specimens to use all of the instrument's capacity (Crowe and Schaefer, 1992).⁶

Onsite Noninstrument-Based Tests

Several manufacturers have developed portable test devices that are variously called kits, handheld tests, or point-of-contact tests. These tests can analyze for a single drug, and some are available that will detect several drugs at the same time. They are suitable for initial testing and provide qualitative results (the drug is present or not found in the sample). The cutoff levels for these tests are set by the manufacturers and usually are consistent with government and industry standards. Staff training is very important when using these devices. Manufacturer's instructions for operation should be strictly followed. An advantage of this method is the immediacy of results; tests can be performed while the youth watches. The tests also can be used outside the agency, such as on home visits. However, agencies should consider and develop protocols for all testing that include consideration of staff and youth safety (Crowe and Schaefer, 1992).⁷

Accuracy and Validity of Onsite Drug Testing

To rate the performance of onsite testing methods, the test results are compared with the results obtained when the same specimen is tested using laboratory instruments, usually GC/MS. When a specimen has a negative result using the onsite test device and a negative result in subsequent testing by GC/MS it is considered a true negative. If the "negative" specimen tests positive by GC/MS, it is considered to be a false negative. When a specimen has a positive result by the test device and a positive result by GC/MS, it is considered a true positive. A specimen that tests positive with an onsite testing device and subsequently tests negative by GC/MS is considered a false positive.

False positives and false negatives are more likely to occur with specimens in which the drug concentration is at or near the cutoff levels. With those specimens, the varying sensitivities of the testing methods can produce the differing results. It is thus more accurate to refer to the testing result as an unconfirmed positive when the presence of the drug was accurately detected but the quantity was inaccurately determined. The likelihood is that most specimens in field situations will not have drug concentrations near the cutoff levels. With drug concentrations noticeably above or below the cutoff levels, the number of true positives and true negatives increases.

Onsite drug testing results can also be affected by food such as poppy seeds and foods containing hemp derivatives and by over-the-counter products such as some cold medications consumed by the individual being tested. Results can also be affected by products added to the urine specimen after urination. Laboratory testing can detect the different molecular structure of cross-reacting agents and can determine if an adulterant has been added to the specimen in an effort to mask the test result. Therefore, unless the person being tested admits to using drugs after a positive test result, positive test results should be confirmed by a laboratory test, preferably GC/MS.

Table 3: Sweat Analysis Summary The body constantly discharges waste through sweat. By placing an absorption pad on the skin, sweat and the components it contains can be collected and analyzed. The patch may be worn for a period of from a few days to about 2 weeks (Baer and Booher, 1994). Sweat analysis technologies are still in development and are not used widely. In the future, patches may be designed to include a microelectronic chip that will give immediate results and detect the specific date on which particular substances were used (Mieczkowski and Lersch, 1997). Roughly, costs are $7 for a patch, up to $15 for an initial screening, and up to $22 for a confirmation test (Jackson and Borrowman, 1998). Substances Tested Marijuana, cocaine, amphetamines, barbiturates, opiates, phencyclidine, benzodiazepines. Benefits Specimen collection is relatively noninvasive, and the patches are easier to collect, handle, store, and transport than urine. The period for which drugs may be detected is about 2 weeks (compared with much shorter periods for most drugs when tested by urinalysis). Sweat analysis also offers the ability to detect drug intake for as long as the youth is wearing the patch. Use of sweat patches allows for more flexibility in scheduling testing, and as it is worn continuously, it reduces the potential for youth to plan their substance use to avoid detection. Patches are designed so tampering with them is apparent. Secretion of drugs and/or metabolites through sweat is not affected by consuming water or other substances. Although sweat analysis costs more than urinalysis, it may be more cost effective because it can be conducted less often. Disadvantages It takes time for enough sweat to accumulate for analysis. Therefore, immediate detection of recent substance use is not feasible. There are no proficiency testing programs for administrators. Thus, accuracy of results may be questioned. Sources for lists: Baer and Booher, 1994; Jackson and Borrowman, 1998; Mieczkowski and Lersch, 1997.

To ensure the greatest accuracy when using onsite testing devices, it is advisable to establish protocols for collection and testing that minimize the numbers of false positives and false negatives. Suggested procedures are:

• Appropriately identify the person being tested.

• Observe all specimen collections.

• Follow appropriate chain-of-custody procedures.

• Obtain information from manufacturers of onsite test devices on the foods or products that may affect their test results.

• Require youth to report consumption of any prescribed or over-the-counter medication or use of any of the identified food products.

• Prohibit consumption of identified cross-reacting foods, over-the-counter medication, or other products.

• Check urine samples for adulterants.

• Conduct confirmation testing when positive test results are disputed.