Forensic Lab Backlog: What Impact the Storage of Marijuana Samples Has on Analysis Results

Forensic laboratories worldwide are under mounting pressure to keep up with the growing volume of chemical analysis cases. Controlled substance analysis is among the most affected areas, with case volume often hampering justice and affecting the validity of results. A recent study by the Forensic Laboratory of the Federal District Civil Police in Brazil examined more than 11,000 marijuana samples and concluded that storage time and conditions played a significant factor in result consistency.

What generates the Backlog?

A "backlogged case" is one which is not reported beyond a lab's usual handling time. But what is a lab's usual handling time varies from lab to lab. Budget cuts, a flood of new psychoactive substances (NPS), and more casework have overwhelmed forensic chemists globally. Every new synthetic compound takes specialized apparatus, reference material, and experienced analysts — all of which contribute to test time. Budgetary constraints and a lack of staff in most countries mean that evidence sits untested for months or even years, at the expense of both quality and credibility.

THC Degradation and Its Impact

It was seen that poor storage conditions significantly reduce THC levels, with that of cannabinol (CBN) rising. Such conversion affects thin-layer chromatography (TLC) findings, a common test in forensic laboratories under limited resources.

This previous work confirms that THC breakdown is faster with light and higher temperatures but is retarded under lower and darker conditions. The longer that a case remains in backlog, the higher the likelihood of inconclusive or confusing results when analyzed.

Challenges in Analytical Methods

Even decades after research, there is no one common standard for marijuana identification. Laboratories utilize different methods like GC-MS, HPLC, and TLC, each having advantages of its own. TLC remains popular in low-resource settings because it is simple, cheap, and useful for screening multiple samples at the same time. The accuracy of TLC, however, depends largely on the chemical stability of stored samples, which backlog conditions can readily infringe.

The Way Forward

To lower forensic delays, professionals suggest enhancing evidence storage procedures, investing in new analytical equipment, and adding more trained analysts. The research points out that clearing backlog is not just about speed — it's also about maintaining evidence integrity. Timely testing and right handling are necessary, or forensic results can be scientifically inconclusive, compromising the quest for justice.