Effect of drug precursors and chemicals relevant to clandestine laboratory investigation on plastic bags used for collection and storage.

In the area of clandestine laboratory investigations, plastic bags are used to collect and store evidence, such as solvents, precursors, and other compounds usually employed for the manufacturing of drugs (although liquids may be stored in glass containers within the bags first). In this study, three different types of plastic bags were provided by the NSW Police Force and investigated for their suitability for evidence collection: two different types of low-density polyethylene (LDPE) bags and one type of polyvinyl chloride (PVC) bag. Three different experiments were carried out: (1) storing relevant chemicals in the bags for up to three months; (2) exposing the bags including their content to accelerated conditions using a weatherometer, and (3) simulating an expected real case scenario. This study indicates that drugs and related chemicals stored in plastic bags may lead to a change in the composition of the chemical and an alteration or degradation of the plastic bag. All experiments led to the same conclusion: the polyvinyl chloride bags appeared to be the most affected. LDPE bags seem to be more appropriate for routine use, although it has been established they are not suitable for the collection of liquids (unless pre-packaged in, for instance, a glass container).

The mechanical properties of plastic evidence bags used for collection and storage of drug chemicals relevant to clandestine laboratory investigations.

The effectiveness of three types of plastic bags used by the New South Wales Police Force for the storage of clandestine drug evidence has been investigated through a comparison of mechanical properties. The tensile and tear properties of "as received" low-density polyethylene (LDPE) and poly(vinyl chloride) (PVC) bags do not show major differences such that one type would be favoured over the other. However, the mechanical properties of the bags once exposed to a range of chemicals routinely collected as drug evidence have been shown to be influenced as a result of different chemical interactions. Although an interaction of reagents/solvents with an additive within the LDPE bags is proposed to influence the mechanical properties of the bags, the change in properties has been shown to be less severe than that observed for the PVC bag, where softening and damage of the bags results due to absorption of reagents.