Anne ImObersteg is a court-qualified expert in forensic toxicology. Toxicology is traditionally defined as "the science of poisons." Just about any chemical substance, if taken in large enough quantities, can become a poison to the human organism. As Paracelsus (1500AD)is often quoted as saying, "All substances are poisons; there is none which is not a poison. The right dose differentiates a poison and a remedy."

Toxicology also is the study of the harmful effects of agents and the mechanisms responsible for the effects. Thus, toxicology encompasses the fields of physiology, pharmacology, and analytical chemistry. The Forensic Toxicologist must not only have experience in the analytical testing of biological specimens, but also be able to interpret the results in a legal setting where the issues of performance impairment, influence, and abuse are litigated.

Anne ImObersteg has analyzed thousands of biological specimens utilizing a variety of analytical procedures and instruments. She also has testified several hundereds of times as an expert on the analysis of biological specimens and the impact of the analytical results on human mental and physical peformance.


OVERVIEW OF TESTING METHODS

Laboratory analysis of a biological sample is performed in two separate stages. The first analysis is generally called an “initial test”, “screening”, or “presumptive” test. Generally, the screening test is performed by an immunoassay kit, which is useful in separating out negative specimens from specimens that may potentially be positive for a particular drug or drug class. A test result that is considered “negative” is generally not tested any further. "Positive" results are sent on for confirmation via a more specific instrument such as a Gas Chromatograph-Mass Spectrometer (GC/MS). This instrument allows drugs in the case sample to be identified by evaluating the actual molecular structure of the drug.

As with any instrument, the quality and value of the data achieved though analytical analysis is a function of how the instrument is maintained and operated. Confirmation methods must be validated to ensure the reliable analysis of specimens. The instrument must be used in the proper manner as well. The calibrators that establish the quantitation of the result, and the controls that check the proper results of the calibrators, must be used in the analytical run and fall within acceptable ranges of accuracy. All of these testing aspects can be evaluated by Anne ImObersteg and Associates.

INTERPRETING ANALYTICAL RESULTS

The key questions in most court adjudications are whether the drug found may cause influence, and, if there is possible influence, whether there is evidence of impairment. While it is impossible to have impairment without influence, it is entirely possible to have influence without impairment.

To determine the answers to these questions, interpretation of analytical results must be done by a forensic toxicologist. Several issues need to be considered, including, but not limited to the following:

WHAT DRUG OR DRUG CLASS WAS FOUND IN THE SPECIMEN?
Drugs can be classified in many ways. The most common way is by general effect. Most drugs fall into one of 5 classes: stimulants, depressants, psychedelics, inhalants and miscellaneous. Ingested drugs metabolize into other compounds. Some of these metabolites have no effect on the body and some assert their own effect. For example, cocaine breaks down into the non-active metabolite benzoylecgonine, and methamphetamine breaks down into the active drug amphetamine. If only a non-active substance is found in the blood/urine, there is no scientific evidence of influence or impairment.

WHAT ARE THE POSSIBLE EFFECTS OF THE DRUG?
The intensity of drug effects and their onset of action can be dependent on their routes of administration. If a drug is taken orally, it can take between 20 and 30 minutes before the drug reaches the system and gives an effect. Nasal administration of the drug takes even longer. Injection and inhalation are by far the fastest route of administration, sometimes taking only 10 to 15 seconds for the drug to take effect. Drug effects dissipate long before evidence of ingestion disappears from the biological matrix. It is well understood in the scientific community that a positive result on a drug test does not automatically equate to evidence of influence.

WHAT TYPE OF SPECIMEN WAS COLLECTED?
The choice of sample collected is of prime importance. Urine samples should only be valid to sustain a charge of drug use, not influence. Since urine represents a filtration of blood since the time of the last void, it is conceivable that the urine may show a significant drug level while a simultaneous blood sample would show minimal or no levels. In addition, the drug may be present in the urine long after the effects of the drug has worn off. Thus, “urine is only acceptable to show use of a drug, and not impairment” (Consensus Development Panel, 1985).

A blood specimen will reflect the concentration of the drug at the time of the blood draw. However, mere presence in the blood does not necessarily mean that the user was under the influence of the drug; drugs last in the blood long after the active efects have vanished. Also, the user's tolerance to the drug may be such that there may be no net effect on the body at the particular blood concentration.

IS THERE EVIDENCE OF DRUG EFFECTS NOTED?
The police report should have documentation of the physiological effects seen by the officer. It is important that the officer follow the entire standardized 12-step drug evaluation and classification procedure (see the DUI/DWI link on the left menu). The toxicologist will take all the information gathered by the officer and determine if all the signs/effects seen by the officer are consistent with the expected drug effects.