Abstract Objective: This study compared three model decontaminant solutions (distilled water, 10% distilled water and soap and methanol) for their ability to remove salicylic acid and aminophylline from an in vitro skin model. Materials and methods: Human abdominal skin was dosed with 20 µL of either [(14)C]-aminophylline or [(14)C]-salicylic acid on 1 cm(2) per skin. After each exposure time (5, 30 and 60 min post-dosing, respectively), surface skin was washed three times with each solution and tape stripped 10 times. Wash solutions, tape strips, receptor fluid and remaining skin were then analyzed with liquid scintillation counting to quantify the amount of salicylic acid and aminophylline. Results: Total mass balance recovery for each chemical at three time exposure points was between 73.6 and 101.5%, except at 60 min where aminophylline was only 42.5%. Majority of salicylic acid and aminophylline were recovered from washing solution when compared to stratum corneum, epidermis, dermis, surrounding skin and receptor fluid. Conclusion: The three tested decontaminates possessed similar effectiveness in removing lipophilic and hydrophilic chemicals from the skin. Due to diminishing decontamination efficacy with time, it is suggested that skin should be washed as soon as possible following contamination to minimize percutaneous penetration and the deleterious effects associated with skin reservoir content.
In sexual assault cases, particularly those involving internal child sex trafficking (ICST), victims often hide their semen-stained clothing. This can result in a lag time of several months before the items are laundered and subsequently seized during a criminal investigation. Although it has been demonstrated previously that DNA can be recovered from clothing washed immediately after semen deposition, laundered items of clothing are not routinely examined in ICST cases, due to the assumption that the time delay and washing would result in no detectable DNA. The aim of this study was to examine whether viable DNA profiles could be recovered from laundered semen stains where there has been a significant lag time between semen deposition from one or more individuals and one or more washes of the stained clothing. Items of UK school uniform (T-shirts, trousers, tights) were stained with fresh semen (either from a single donor or a 1:1 mixture from two donors) and stored in a wardrobe for eight months. Stained and unstained items (socks) were then washed at 30°C or 60°C and with non-biological or biological detergent. DNA samples extracted from the semen-stained sites and from the unstained socks were quantified and profiled. High quantities of DNA, (6-18μg) matching the DNA profiles of the semen donors, were recovered from all semen-stained clothing that had been laundered once, irrespective of wash conditions. This quantity,and profile quality,did not decline significantly with multiple washes. The two donor semen samples yielded ∼10-fold more DNA from the T-shirts than from the trousers. This disparity resulted in the T-shirts yielding a ∼1:1 mixture of DNA from the two donors, whereas the trousers yielded a major DNA profile matching only that of the second donor. The quantities of DNA recovered from the unstained socks were an order of magnitude lower, with most of the DNA being attributable to the donor of the semen on the stained clothing within the same wash, demonstrating the transfer of semen-derived DNA among items of clothing in the washing machine. This study demonstrates that complete DNA profiles can be obtained from laundered semen stains on school uniform-type clothing, with an eight-month lag time between semen deposition and laundering, despite multiple washes and stains from two semen donors. These data emphasise the need to recover and examine the clothing of victims for semen and DNA evidence, even if the clothing has been stored for several months or washed multiple times since the sexual offence took place.
Microplastic fibers make up a large proportion of microplastics found in the environment, especially in urban areas. There is good reason to consider synthetic textiles a major source of microplastic fibers and it will not diminish since the use of synthetic fabrics, especially polyester, continues to increase. In this study we provide quantitative data regarding the size and mass of microplastic fibers released from synthetic (polyester) textiles during simulated home washing under controlled laboratory conditions. Consideration of fabric structure, washing conditions (use of detergents, temperature, wash duration, sequential washings) allowed us to study the propensity of fiber shedding in a mechanistic way. Thousands of individual fibers were measured (number, length) from each wash solution to provide a robust data set on which to draw conclusions. Among all the variables tested, the use of detergent appeared to affect the total mass of fibers released the most, yet the detergent composition (liquid or powder) or overdosing of detergent did not significantly influence microplastic release. Despite different release quantities due to the addition of a surfactant (approximately 0.025 and 0.1 mg fibers/g textile washed, without and with detergent, respectively), the overall microplastic fiber length profile remained similar regardless of wash condition or fabric structure, with the vast majority of fibers ranging between 100 m and 800 m in length irrespective of wash cycle number. This indicates that the fiber staple length and/or debris encapsulated inside the fabric from the yarn spinning could be directly responsible for releasing stray fibers. This study serves as a first look towards understanding the physical properties of the textile itself to better understand the mechanisms of fiber shedding in the context of microplastic fiber release into laundry wash water.
Reducing exposure to ticks can help prevent Lyme disease and other tickborne diseases. Although it is currently recommended to dry clothes on high heat for one hour to kill ticks on clothing after spending time outdoors, this recommendation is based on a single published study of tick survival under various washing conditions and a predetermined one-hour drying time. We conducted a series of tests to investigate the effects of temperature, humidity, and drying time on killing nymphal and adult blacklegged ticks (Ixodes scapularis). Muslin bags containing 5 ticks each were washed then dried or dried only with six cotton towels during each drying cycle. All nymphal and adult ticks were killed when exposed to wash cycles when the water temperature reached ≥54°C (≥130°F); however, 50% of ticks survived hot water washes when the water temperature was <54°C. The majority (94%) of ticks survived warm washes [temperature range, 27-46°C (80-115°F)] and all ticks survived cold washes [15-27°C (59-80°F)]. When subsequently dried on high heat setting [54-85°C (129-185°F)], it took 50min to kill all ticks (95% confidence limit, 55min). Most significantly, we found that all adult and nymphal ticks died when placed directly in the dryer with dry towels and dried for 4min on high heat (95% confidence limit, 6min). We have identified effective, easily implemented methods to rid clothing of ticks after spending time outdoors. Placing clothing directly in a dryer and drying for a minimum of 6min on high heat will effectively kill ticks on clothing. If clothing is soiled and requires washing first, our results indicate clothing should be washed with water temperature ≥54°C (≥130°F) to kill ticks. When practiced with other tick-bite prevention methods, these techniques could further reduce the risk of acquiring tickborne diseases.
Olyset Duo is a new long-lasting insecticidal net treated with permethrin (a pyrethroid) and pyriproxyfen, an insect growth regulator that disrupts the maturation of oocytes in mosquitoes exposed to the net. We tested the Olyset Duo net against pyrethroid-resistant Anopheles gambiae mosquitoes, which transmit malaria parasites, in laboratory bioassays and in a trial in Benin using experimental huts that closely resemble local habitations. Host-seeking mosquitoes that entered to feed were free to contact the occupied nets and were collected the next morning from exit traps. Surviving blood-fed mosquitoes were observed for effects on reproduction. Control nets were treated with pyrethroid only or pyriproxyfen only, and nets were tested unwashed and after 20 standardized washes. The Olyset Duo net showed improved efficacy and wash resistance relative to the pyrethroid-treated net in terms of mosquito mortality and prevention of blood feeding. The production of offspring among surviving blood-fed A. gambiae in the hut trial was reduced by the pyriproxyfen-treated net and the Olyset Duo net both before washing (90 and 71% reduction, respectively) and after washing (38 and 43% reduction, respectively). The degree of reproductive suppression in the hut trial was predicted by laboratory tunnel tests but not by cone bioassays. The overall reduction in reproductive rate of A. gambiae with the Olyset Duo net in the trial was 94% with no washing and 78% after 20 washes. The Olyset Duo net has the potential to provide community control of mosquito populations and reduce malaria transmission in areas of high insecticide resistance.
The efficacy of four plant-derived antimicrobials (PDAs), namely carvacrol, thymol, β-resorcylic acid, and caprylic acid, with or without hydrogen peroxide (HP), as antimicrobial wash and chitosan based coating for reducing Listeria monocytogenes (LM) on cantaloupes was investigated. Cantaloupe rind plugs inoculated with LM (10(7) CFU/cm(2)) were washed for 3, 6, 10 min at 25 °C or 1, 3, 5 min at 55 or 65 °C in water, or water containing 2% PDAs with or without 2% HP. Additionally, inoculated cantaloupes (10(8) CFU/fruit) washed with 2% PDA-HP combinations at 55 or 65 °C (5 min) were cut into rindless cubical pieces, stored at 4 °C for 7 days and sampled for LM. Furthermore, inoculated plugs coated with 2% PDAs were stored for 7 days and sampled for surviving LM. Individual PDA washes reduced LM on rinds by ≥2.5 log CFU/cm(2) by 3 min (P < 0.05). PDA-HP combinations decreased LM to undetectable levels by 5 min at 55, 65 °C, and 10 min at 25 °C (P < 0.05) and reduced LM transfer from cantaloupe surface to interior (P < 0.0001). All PDA coating treatments reduced LM on cantaloupe to undetectable levels by 5 days (P < 0.05). Results indicate that PDAs alone, or with HP could be used to reduce LM on cantaloupes.
For centuries people have washed away their guilt by washing their hands. Do people need to wash their own hands, or is it enough to watch other people wash their hands? To induce guilt, we had participants write about a past wrong they had committed. Next, they washed their hands, watched a washing-hands video, or watched a typing-hands video. After the study was over, participants could help a Ph.D. student complete her dissertation by taking some questionnaires home and returning them within 3 weeks. Results showed that guilt and helping behavior were lowest among participants who washed their hands, followed by participants who watched a washing-hands video, followed by participants who watched a typing-hands video. Guilt mediated the effects of cleansing on helping. These findings suggest that washing one’s own hands, or even watching someone else wash their hands, can wash away one’s guilt and lead to less helpful behavior.
Face cleanliness is a core component of the SAFE (Surgery, Antibiotics, Facial cleanliness, and Environmental improvements) strategy for trachoma control. Understanding knowledge, attitudes, and behaviors related to face washing may be helpful for designing effective interventions for improving facial cleanliness.
Analysis of nail clippings may be a useful back-up for hair analysis when hair is unavailable. One aspect of using nails or hair is the ability to analyze whether drug present is from ingestion or from contamination. A common method of three 15-s rinses in methanol failed to remove drug from nails that had been soaked in either 5 or 50 μg/mL cocaine, methamphetamine or morphine for 1 h. While methanol rinsing did not remove contaminating drug, washing the nails soaked with 5 and 50 μg/mL of these drugs with an extended wash, a method developed for hair analysis and consisting of a 15-min isopropanol wash, and three 30-min and two 60-min phosphate buffer-0.1% albumin washes, when applied to nails did remove most of the contaminating drug. The drug left in the nails after extended washing could be interpreted as contamination by applying a wash criterion that is routinely applied in hair analysis. Successful decontamination of the soaked contaminated nail model was followed by applying this extended wash method to presumptive positive nail samples identified in workplace testing. While the extended buffer wash and wash criterion distinguish contamination from ingestion with hair, we failed to demonstrate that the method effectively differentiates contamination from ingestion with nails.
Nanosized Molecularly Imprinted Polymers (nanoMIPs) are designed artificial nanoreceptors with a predetermined selectivity and specificity for a given analyte, lately proposed as a replacement to antibodies in immunoassays. The nanoMIP-plate preparation based on nanoparticle adsorption was studied with the aim to rationally identify and discuss the critical points in the nanoMIP-assay development, in an example based on the iron homeostasis biomarker hepcidin and hepcidin-specific nanoMIPs (Kd = 9nM). Plates were prepared by deposition and drying of nanoMIP (0.5-4µg/well), or by nanoMIPs co-depositions (proteins, PVA). Rehydration (> 1h) of dry nanoMIP-plates showed the reconstitution of the imprinted binding sites. NanoMIP-plate mechanical stresses (several washings; pipetting) caused nanoMIP desorption (~90%). After 10 washes the quantity of nanoMIP was 0.2µg/well, the imprinted binding sites were ~270 fmol/well, their accessibility the 92%. Co-depositions resulted in higher amount of adsorbed nanomaterial (1.2µg/well), but low accessibility of the imprinted binding sites (2-47%). Tested in a competitive sequential assay, using as competitor horseradish peroxidase conjugate to hepcidin, the nanoMIP-plate permitted to determine hepcidin in serum samples, yet with a narrow dynamic range of response (0.9-10nM). Critical points in the assay were: the instability of the nanoMIP adsorption, which lead to the progressive loss of binding sites/well, and the affinity of the nanoMIP for the analyte (Kd = 9nM), which corresponds to kinetics dissociation constants on the time-scale of the washing lengths (minutes), thus compatible with the release of the bound hepcidin during the washings. The found limits set the conditions to develop a successful nanoMIP-assay: (i) stable microplate derivatization; (ii) maximized number of imprinted binding sites/well; (iii) nanoMIP/analyte equilibrium not perturbed on the time scale of the minutes (i.e. Kd ~ pM).