**5. Conclusion**

*Forensic Analysis - Scientific and Medical Techniques and Evidence under the Microscope*

When the presence of drugs is confirmed in oral fluid, the person under investigation may request the counter-analysis of another aliquot (B) of the saliva sample. This second test can be performed at the same laboratory that analysed the first aliquot (A) of the saliva sample or at another laboratory chosen by the subject in question. Aliquot B must be accompanied by a chain of custody form and include information regarding the results of the original analysis and the cut-offs used. Any laboratory that conducts analysis on aliquot B of the saliva sample must have documentation to demonstrate the use of validated analysis methodologies that meet the precision and accuracy criteria appropriate to the required analyses. It is crucial to guarantee the chain of custody [55], a documented procedure designed to ensure the authenticity, integrity and traceability of a sample from the moment of collection to its disposal. Following the proper chain of custody protocol is fundamental in the reconstruction process and ensures that the sample can be located at any point, unequivocally identified, stored correctly under the right conditions, and protected from tampering and voluntary or involuntary adulterations in all phases. Documentation of the chain of custody must also record every movement and manipulation of the sample, on which dates and under whose care. In the judicial field, the chain of custody is deemed broken in any of the following scenarios (these shortcomings will lead to dispute and may even constitte instances

*4.3.2 The activity of the toxicology laboratory for forensic purposes*

**150**

of mystification):

assessment.

• Absence of security seals.

safety and reliability;

• Insufficient sample volume for testing.

• Containers not intact and evident loss of sample.

the analysis of substances of abuse on saliva samples);

• Missing or non-identical barcodes.

• Missing documentation (supposed to be attached).

• Absence of the informed consent of the person subjected to analytical

• Broken or tampered safety seals on sample containers or transport container.

On the basis of what has been said thus far, it is evident that laboratory staff are required to fulfil many responsibilities, with potential repercussions in the forensic field in the event of proven professional malpractice. It is therefore necessary to:

confirmation analysis), the suitability of resources and the guaranteed level of

• ensure the availability of sufficient, adequately trained staff with the necessary experience to monitor and conduct the required laboratory tests (specifically,

• define the type of services that can be provided (screening analysis and

• assure the competence of laboratory staff, document in-service training, validate the analytical method, and re-evaluate work performance;

Oral fluid testing for drugs of abuse offers significant advantages. A saliva sample can be collected under direct observation with reduced risk of adulteration and substitution and in a less embarrassing or unpleasant manner than urine or blood collection. As oral fluid collection is non-invasive, most people find the procedure more acceptable than having to provide other biological matrices, and suitable hygiene conditions can be respected while the donor is under the collector's observation.

By providing an estimate of the actual circulating amount, the measurement of a drug concentration in oral fluid can be used for the determination of intoxication. In fact, measurements of oral fluid drug concentrations will usually be of value only if they accurately reflect the plasma level. Therefore, before designing a useful model for the salivary secretion of drugs, it is necessary to constantly update information about the relationship between the saliva concentration level of each drug and its plasma concentration level, the mechanisms by which drugs enter oral fluid, and also the effect on salivary flow rate, production in the salivary glands, and the nature of any protein binding in the saliva.

It is very useful to know the limitations and possibilities of salivary analysis in forensic and diagnostic fields. Standardisation of the conditions for collection of oral fluid is strictly essential for achieving reliability and interpretation of the data. Furthermore, appropriate cut-off concentrations need to be established in the development of guidelines for oral fluid testing [56]. In future research, the mechanisms by which drugs enter the saliva must be clarified more adequately.

#### *Forensic Analysis - Scientific and Medical Techniques and Evidence under the Microscope*

These considerations are matters of ongoing discussion in the scientific community, in particular the proposed initial screening and confirmatory cut-offs.

When an oral fluid test is performed on a corpse, the forensic pathologist must be accompanied by a toxicologist for the interpretation of the analytical data. It should also be noted that significant ethical issues are involved in the study of many licit and illicit drugs that preclude or limit the study of their short- and long-term effects under "real-world use" conditions, which means that some knowledge will always remain inaccessible.

Finally, there are some open questions and limitations to consider in salivary analysis for forensic purposes. Despite a substantial number of clinical studies on drug disposition in oral fluid, many psychoactive drugs have not been studied. Benzodiazepines and barbiturates and some opioid products have received limited or no evaluation in oral fluid; meanwhile, there is a lack of controlled dosing studies of hallucinogens in humans. Furthermore, the dynamic nature of oral fluid, especially its pH, can substantially affect drug concentrations of basic drugs. It follows that, to date, in a forensic context, the result of an oral fluid test remains questionable, not only for reasons strictly connected to pharmacokinetic and metabolic characteristics, but also for purely analytical reasons:

a.difficulty in applying standardised procedures for sampling;


Therefore, salivary analysis for forensic purposes, now and in the future, necessarily requires a union between highly qualified personnel (able to apply analytical methods and interpret results in the light of up-to-date scientific knowledge) and toxicological laboratories equipped with state-of-the-art instrumentation.

**153**

Italy

**Author details**

Roberto Scendoni

Department of Law, Institute of Legal Medicine, University of Macerata, Macerata,

© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

\*Address all correspondence to: r.scendoni@unimc.it

provided the original work is properly cited.

*Salivary Analysis for Medico-Legal and Forensic Toxicological Purposes*

*DOI: http://dx.doi.org/10.5772/intechopen.95625*

*Salivary Analysis for Medico-Legal and Forensic Toxicological Purposes DOI: http://dx.doi.org/10.5772/intechopen.95625*

*Forensic Analysis - Scientific and Medical Techniques and Evidence under the Microscope*

in particular the proposed initial screening and confirmatory cut-offs.

characteristics, but also for purely analytical reasons:

function of the variability of salivary pH;

intranasal use or inhalation.

a.difficulty in applying standardised procedures for sampling;

always remain inaccessible.

counter-analyses;

procedures.

These considerations are matters of ongoing discussion in the scientific community,

When an oral fluid test is performed on a corpse, the forensic pathologist must be accompanied by a toxicologist for the interpretation of the analytical data. It should also be noted that significant ethical issues are involved in the study of many licit and illicit drugs that preclude or limit the study of their short- and long-term effects under "real-world use" conditions, which means that some knowledge will

Finally, there are some open questions and limitations to consider in salivary analysis for forensic purposes. Despite a substantial number of clinical studies on drug disposition in oral fluid, many psychoactive drugs have not been studied. Benzodiazepines and barbiturates and some opioid products have received limited or no evaluation in oral fluid; meanwhile, there is a lack of controlled dosing studies of hallucinogens in humans. Furthermore, the dynamic nature of oral fluid, especially its pH, can substantially affect drug concentrations of basic drugs. It follows that, to date, in a forensic context, the result of an oral fluid test remains questionable, not only for reasons strictly connected to pharmacokinetic and metabolic

b.frequent smallness of the sample compared to conventional matrices (e.g. blood) with consequent limitations in terms of multiclass analyses and sampling for

c.variability of the relationship between salivary and blood concentrations as a

d.possibility of contamination of the oral cavity after ingestion of a substance via

Therefore, salivary analysis for forensic purposes, now and in the future, necessarily requires a union between highly qualified personnel (able to apply analytical methods and interpret results in the light of up-to-date scientific knowledge) and

e.laboratory deficiencies and/or incorrect application of the analytical

toxicological laboratories equipped with state-of-the-art instrumentation.

**152**
