RESUMEN
Latent fingermarks are enhanced in order to be visible and available for comparison to determine source. Once a fingermark has been identified to a source, the activity that led to it being left on a particular surface may need to be determined. It has been previously shown that under certain conditions fingermarks initially deposited onto a surface (the primary transfer) can be transferred on to another substrate through direct contact - secondary transfer. This study investigates the possibility of secondary and subsequent tertiary transfer using sticky notes. To explore secondary transfer, fingermarks were deposited directly onto two different brands of sticky notes, spanning the adhesive and non-adhesive areas, and then placed in direct contact with paper for up to 72 h under a 5 kg weight. For some donors, there was transfer of fingermarks from the sticky note to the paper, with better results for the adhesive areas. The quality of the transferred fingermarks was dependent on initial fingermark quality and the transferred fingermark was a mirror image of the original. The type of paper used as the secondary substrate was also shown to have an effect. Given the adhesive nature of sticky notes tertiary transfer was also investigated and the potential to lift fingermarks from a glass slide and transfer them onto paper or a second glass slide. In the case of transfer to paper, there were only tertiary transferred fingermarks considered to be of useful quality (score 3 or 4) in 6% of samples and a further 33% of samples were detected but provided evidence of contact only (score 1 or 2) (n = 120). For transfer to glass, tertiary transferred samples were of poorer quality with no useful fingermarks and only 3% of samples scoring 1 or 2 (n = 120). The latter was in part due to the deposition of sticky note adhesive traces obscuring the fingermarks. In the case of tertiary transfer, fingermarks on the final tertiary surface were in the correct orientation. This work demonstrates that whilst tertiary transfer of fingermarks is possible under the laboratory conditions used, the likelihood of the effective transfer of a useful and potentially identifiable fingermark is in reality low.
RESUMEN
Laundering of textiles is a significant source of waterborne microfiber pollution, and solutions are now being sought to mitigate this issue including improvements in clothing technology and integration of filtration systems into washing machines. Vented tumble dryers are a potential source of airborne microfiber pollution, as their built-in lint filtration systems have been found to be inefficient with significant quantities of textile microfibers being released to the external environment through their exhaust air ducts. The present study is the first to evaluate the impact of condenser dryers, finding that they are significant contributors to waterborne microfiber pollution from the lint filter (if users clean this with water), the condenser and the condensed water. Microfiber release from drying of real consumer loads in condenser and vented tumble dryers was compared, finding that real loads release surprisingly high levels of microfibers (total 341.5 ± 126.0 ppm for those dried in a condenser dryer and 256.0 ± 74.2 ppm for those dried in a vented dryer), similar in quantity to microfibers produced during the first highly-shedding drying cycle of a new T-shirt load (total 321.4 ± 11.2 ppm) in a condenser dryer. Vented dryers were found to be significant contributors to waterborne microfiber pollution if consumers clean the lint filter with water in accordance with some published appliance usage instructions, as most (86.1 ± 5.5% for the real consumer loads tested) of the microfibers generated during vented tumble drying were collected on the lint filter. Therefore, tumble dryers are a significant source of waterborne and (for vented dryers) airborne microfiber pollution. While reducing the pore size of tumble dryer lint filters and instructing consumers to dispose of fibers collected on lint filters as municipal solid waste could help reduce the issue, more sophisticated engineering solutions will likely be required to achieve a more comprehensive solution.
