Jennifer L. L. Morgan

Post-consumer recycled (PCR) plastics are increasingly used in sensitive applications such as cosmetic and home care packaging. However, their safe use requires a robust assessment of potentially releasable contaminants originating from previous use and recycling processes. Building on the work of CosPaTox (a European consortium of companies involved in cosmetic products and their packaging) and the PCR pellet analysis methodology developed therein, this study presents the first interlaboratory evaluation of chemical release analysis from recycled high-density polyethylene (rHDPE) pellets that provides insights into the different factors influencing reproducibility. Seven laboratories, belonging to different stakeholder groups within the supply chain of recycled plastics (brand owners, suppliers, and service labs), participated in a harmonized study in which pellets were extracted with 95% ethanol at 60 °C for seven days and subsequently analyzed by gas chromatography–mass spectrometry (GC-MS). Using a per-substance comparison approach, variability introduced at each stage of the analytical workflow was systematically assessed, including (1) extraction, (2) GC-MS analysis, and (3) chromatogram evaluation. The results show that differences in extraction and instrumental analysis are the main contributors to interlaboratory variability (median standard deviation between measurements climbing to ca. 26% and ca. 43%, respectively, vs. 12% in a single lab and on single equipment). Chromatogram evaluation was identified as a further source of variation (increasing median standard deviation to 52 to 55% versus ca. 43% if a single lab evaluated the chromatograms). As such, this study provides new insight into the reproducibility of GC-MS screening methods for recycled plastics and establishes a benchmark for variability in pellet-based safety assessments. The findings support the harmonization of analytical workflows and strengthen confidence in the safety evaluation of PCR materials.

The increasing use of post-consumer recycled (PCR) plastics in sensitive packaging applications requires robust approaches for assessing chemical contaminants potentially introduced during previous use and recycling. Safety assessments based on finished packaging, however, can be resource-intensive and may hinder efficient material screening at an early stage. Here, we evaluate a pellet-based migration screening approach for recycled high-density polyethylene (rHDPE) as a potential representative and conservative alternative to testing finished packaging. Gas chromatography–mass spectrometry (GC–MS) was used to characterize substances released from rHDPE pellets into dichloromethane, 95% ethanol, and 50% ethanol under controlled time and temperature conditions. Key substance groups included alkanes and alkenes, fatty acid derivates, phthalates, salicylates, alkyl benzoates and antioxidants. Substance release kinetics were systematically investigated to identify conditions providing a representative or conservative estimate of the release potential. Most substances exhibited comparable release profiles, reaching approximately 85% of their maximum concentrations after 3 days at 40 °C in dichloromethane and after 7 days at 60 °C in ethanol. The outcomes of testing on pellets were subsequently assessed in comparison with testing on corresponding finished rHDPE bottles. For most identifiable substances, pellet testing yielded concentrations comparable to or higher than those measured in bottles, indicating that the approach can adequately capture the substance release potential without requiring production of finished packaging. A limited number of substance-specific deviations were identified and further evaluated; none were considered critical for a typical safety assessment. These findings provide experimental evidence that rHDPE pellets can serve as a representative and generally conservative test material for chemical safety screening of recycled plastics, enabling more efficient material qualification and facilitating the broader use of PCR plastics in contact-sensitive packaging applications.

Aluminum hydrolysis chemistry is an important part of modern society because of the dominance of Al(III) as a highly effective antiperspirant active. However, the century-old chemistry centered on aluminum chloride (ACL) is not comprehensive enough to address all of the in vivo events associated with current commercial antiperspirants and their mechanism of action. The present study aims to address the knowledge gap among extensively studied benchmark ACL, its modified version aluminum chlorohydrate (ACH), and a more complex but less explored group of aluminum zirconium chlorohydrate glycine complexes (ZAG salts) toward understanding the mechanism of action under consumer-relevant conditions. ACH, which is the Al source used in the manufacture of ZAG salts, provides a bridge between ACL and ZAG chemistry. High viscosity and gel formation driven by pH and a specific Al(III) salt upon hydrolysis are considered the criteria for building an in vivo occlusive mass to retard or stop the flow of sweat to the skin surface, thus providing an antiperspirant effect. Rheological studies indicated that ACL and aluminum zirconium tetrachlorohydrex glycine (TETRA) were the most efficacious salt actives. Spectroscopic studies, diffraction studies, and elemental analysis suggested that small metal oxide and hydroxide species with coparticipating glycine as well as various polynuclear and oligomeric species are the key to gel formation. At a given pH, the key ingredients (NaCl, urea, bovine serum albumin, and lactic acid) in artificial sweat were found to have little influence on Al(III) salt hydrolysis. The effects of the sweat components were mostly limited to local complex formation and kinetic modification. The in vitro comparative experiments with various Al(III) and ZAG salt systems offer unprecedented insights into the chemistry of different salt types, thus paving the way for engineering more efficacious antiperspirant systems.

Airborne particulate matter (PM) pollution is an environmental and health concern. The health impact of PM pollution has typically focused on the respiratory system. The impact of PM pollution on skin has been largely understudied due to the lack of a quantitative method to measure the deposition on skin. This manuscript presents a method to quantify PM pollution on skin using elemental markers as a proxy for PM. Skin tape strips were collected from forehead and buttock of 100 outdoor workers in Beijing, China. Skin samples were analyzed for 19 elemental markers using inductively coupled plasma mass spectrometry. To determine the specific elemental signature of PM for the region, air samples were collected over 7 days for PM < 2.5 μm (PM_2.5) and analyzed for the same 19 elements as the skin samples. An enrichment factor was calculated for each element and the potential source was evaluated. Using the elemental markers unique to PM pollution for the region, the PM concentration deposited on skin was determined to be 0.621–2.53 μg PM_2.5 /cm². This method can be re-applied in different regions and the PM concentration on skin can inform future studies on the health impact of air pollution on skin.

Radiation exposure in combination with other space environmental factors including microgravity, nutritional status, and deconditioning is a concern for long-duration space exploration missions. Astronauts experience altered iron homeostasis due to adaptations to microgravity and an iron-rich food system. Iron intake reaches three to six times the recommended daily allowance due to the use of fortified foods on the International Space Station. Iron is associated with certain optic neuropathies and can potentiate oxidative stress. This study examined the response of eye and vascular tissue to gamma radiation exposure (3 Gy fractionated at 37.5 cGy per day every other day for 8 fractions) in rats fed an adequate-iron diet or a high-iron diet. Twelve-week-old Sprague-Dawley rats were assigned to one of four experimental groups: adequate-iron diet/no radiation (CON), high-iron diet/no radiation (IRON), adequate-iron diet/radiation (RAD), and high-iron diet/radiation (IRON+RAD). Animals were maintained on the corresponding iron diet for 2 weeks before radiation exposure. As previously published, the high-iron diet resulted in elevated blood and liver iron levels. Dietary iron overload altered the radiation response observed in serum analytes, as evidenced by a significant increase in catalase levels and smaller decrease in glutathione peroxidase and total antioxidant capacity levels. 8-OHdG immunostaining, showed increased intensity in the retina after radiation exposure. Gene expression profiles of retinal and aortic vascular samples suggested an interaction between the response to radiation and high dietary iron. This study suggests that the combination of gamma radiation and high dietary iron has deleterious effects on retinal and vascular health and physiology.

During early spaceflights, many crewmembers did not meet their caloric requirements and consequently lost body mass during flight, as assessed by a decrease in postflight body mass. Maintaining body mass during spaceflight is crucial for maintaining crew health and monitoring body mass is thus important to medical operations as well as being a key component of human research. Determining body mass becomes difficult in a microgravity environment. We report data from two mass measurement devices on the International Space Station (ISS): the Russian body mass measuring device (BMMD), which uses spring oscillation physics, and NASA's Space Linear Acceleration Mass Measurement Device (SLAMMD), which uses Newton's second law of motion (F = ma). For 25 crewmembers whose body mass was measured on both devices, significant body mass loss occurred compared to preflight (gravimetric scale) and averaged -4.4% as assessed by BMMD and -2.8% as assessed by SLAMMD. After an initial loss in the first 30 d of flight, body mass remained constant through the rest of the mission, as determined using either device. The mean difference between the two devices was 1.1 kg when the closest SLAMMD and BMMD measurements were compared (6.9 ± 6.2 d apart). Dietary intake during flight is approximately 80% of the World Health Organization estimated requirement and the decrease in body mass follows in-flight energy intake closely on average. Body mass monitoring is important for monitoring crew health during a mission and to help ensure that crewmembers consume adequate energy intake to mitigate the risks of spaceflight.

The purpose of this study was to directly assess sex differences in bone loss, bone biochemistry, and renal stone risk in bed rest. Bed rest simulates some spaceflight effects on human physiology and can be used to address the potential existence of sex-specific effects on bone metabolism and renal stone risk in space. We combined data from the control subjects in five head-down-tilt bed rest studies (combined n = 50 men, 24 women) of differing durations (14-90 days). All subjects were healthy volunteers. Mean age was 35 ± 9 years for women and 33 ± 8 years for men. The main outcome measures were bone density and biochemistry, and renal stone risk chemistry. Before bed rest began, men had higher bone mineral density and content (P < 0.001), and excreted more biomarkers of bone resorption and calcium per day than did women (P < 0.05). These differences remained during bed rest. A number of urine chemistry analytes increased (e.g., calcium) or decreased (e.g., sodium, citrate, and urine volume) significantly for men and women during bed rest. These changes may predispose men to higher stone risk. Men and women do not have substantially different responses to the skeletal unloading of bed rest.

: Bone loss, a key concern for long-duration space travelers, is typically considered a female issue. The number of women who have flown long-duration space missions is now great enough to allow a quantitative comparison of changes in bone and renal stone risk by sex. Participants were 42 astronauts (33 men and 9 women) on long-duration missions to the International Space Station. Bone mineral density (by dual-energy X-ray absorptiometry) and biochemical markers of bone metabolism (from blood and urine samples) were evaluated before and after flight. Data were analyzed in two groups, based on available resistance exercise equipment. Missions were 49 to 215 days in duration, flown between 2000 and 2012. The bone density response to spaceflight was the same for men and women in both exercise groups. The bone mineral density response to flight was the same for men and women, and the typical decrease in bone mineral density (whole body and/or regional) after flight was not observed for either sex for those using an advanced resistive exercise device. Biochemical markers of bone formation and resorption responded similarly in male and female astronauts. The response of urinary supersaturation risk to spaceflight was not significantly different between men and women, although risks were typically increased after flight in both groups, and risks were greater in men than in women before and after flight. The responses of men and women to spaceflight with respect to these measures of bone health were not different. © 2014 American Society for Bone and Mineral Research.