Recent Developments in Synthesis, Properties, Applications and Recycling of Bio-Based Elastomers.

In 2021, global plastics production was 390.7 Mt; in 2022, it was 400.3 Mt, showing an increase of 2.4%, and this rising tendency will increase yearly. Of this data, less than 2% correspond to bio-based plastics. Currently, polymers, including elastomers, are non-recyclable and come from non-renewable sources. Additionally, most elastomers are thermosets, making them complex to recycle and reuse. It takes hundreds to thousands of years to decompose or biodegrade, contributing to plastic waste accumulation, nano and microplastic formation, and environmental pollution. Due to this, the synthesis of elastomers from natural and renewable resources has attracted the attention of researchers and industries. In this review paper, new methods and strategies are proposed for the preparation of bio-based elastomers. The main goals are the advances and improvements in the synthesis, properties, and applications of bio-based elastomers from natural and industrial rubbers, polyurethanes, polyesters, and polyethers, and an approach to their circular economy and sustainability. Olefin metathesis is proposed as a novel and sustainable method for the synthesis of bio-based elastomers, which allows for the depolymerization or degradation of rubbers with the use of essential oils, terpenes, fatty acids, and fatty alcohols from natural resources such as chain transfer agents (CTA) or donors of the terminal groups in the main chain, which allow for control of the molecular weights and functional groups, obtaining new compounds, oligomers, and bio-based elastomers with an added value for the application of new polymers and materials. This tendency contributes to the development of bio-based elastomers that can reduce carbon emissions, avoid cross-contamination from fossil fuels, and obtain a greener material with biodegradable and/or compostable behavior.

Chemical Characterization of Recycled Consumer Products Using Suspect Screening Analysis.

Recycled materials are found in many consumer products as part of a circular economy; however, the chemical content of recycled products is generally uncharacterized. A suspect screening analysis using two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-TOFMS) was applied to 210 products (154 recycled, 56 virgin) across seven categories. Chemicals in products were tentatively identified using a standard spectral library or confirmed using chemical standards. A total of 918 probable chemical structures identified (112 of which were confirmed) in recycled materials versus 587 (110 confirmed) in virgin materials. Identified chemicals were characterized in terms of their functional use and structural class. Recycled paper products and construction materials contained greater numbers of chemicals than virgin products; 733 identified chemicals had greater occurrence in recycled compared to virgin materials. Products made from recycled materials contained greater numbers of fragrances, flame retardants, solvents, biocides, and dyes. The results were clustered to identify groups of chemicals potentially associated with unique chemical sources, and identified chemicals were prioritized for further study using high-throughput hazard and exposure information. While occurrence is not necessarily indicative of risk, these results can be used to inform the expansion of existing models or identify exposure pathways currently neglected in exposure assessments.

Chemical exposures in recently renovated low-income housing: Influence of building materials and occupant activities.

Health disparities in low-income communities may be linked to residential exposures to chemicals infiltrating from the outdoors and characteristics of and sources in the home. Indoor sources comprise those introduced by the occupant as well as releases from building materials. To examine the impact of renovation on indoor pollutants levels and to classify chemicals by predominant indoor sources, we collected indoor air and surface wipes from newly renovated "green" low-income housing units in Boston before and after occupancy. We targeted nearly 100 semivolatile organic compounds (SVOCs) and volatile organic compounds (VOCs), including phthalates, flame retardants, fragrance chemicals, pesticides, antimicrobials, petroleum chemicals, chlorinated solvents, and formaldehyde, as well as particulate matter. All homes had indoor air concentrations that exceeded available risk-based screening levels for at least one chemical. We categorized chemicals as primarily influenced by the occupant or as having building-related sources. While building-related chemicals observed in this study may be specific to the particular housing development, occupant-related findings might be generalizable to similar communities. Among 58 detected chemicals, we distinguished 25 as primarily occupant-related, including fragrance chemicals 6-acetyl-1,1,2,4,4,7-hexamethyltetralin (AHTN) and 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta[g]-2-benzopyran (HHCB). The pre- to post-occupancy patterns of the remaining chemicals suggested important contributions from building materials for some, including dibutyl phthalate and xylene, whereas others, such as diethyl phthalate and formaldehyde, appeared to have both building and occupant sources. Chemical classification by source informs multi-level exposure reduction strategies in low-income housing.

Acetaminophen, pesticide, and diethylhexyl phthalate metabolites, anandamide, and fatty acids in deciduous molars: potential biomarkers of perinatal exposure.

The developing fetus is particularly vulnerable to adverse effects from pharmaceutical and exogenous chemical exposure. Deciduous teeth primarily form over specific periods from the second trimester in utero through the months after birth. We hypothesized that organic chemicals or their metabolites circulating in the bloodstream may sorb into forming dental tissues and remain stored in the tooth thereafter. Our aims were to devise analytical and preparation methods for potentially toxic or beneficial organic chemicals or metabolites in deciduous teeth and to estimate their detection frequencies. The analgesic acetaminophen was stored at greater concentration in a child's second molar than a first molar, consistent with intake, suggesting that acetaminophen concentration in molars may be a biomarker of acetaminophen exposure during molar formation. Chemicals detected by liquid chromatography/tandem mass spectrometry in molars of 21 typically developing children include the endocannabinoid anandamide (86% of children), acetaminophen (43%), and specific metabolites mono-2-ethylhexyl phthalate (MEHP, of plasticizer di-2-ethylhexyl phthalate, 29%), 3,5,6-trichloro-2-pyridinol (TCPy, of organophosphate (OP) insecticide chlorpyrifos, 10%), and 2-isopropyl-6-methyl-4-pyrimidinol (IMPy, of OP insecticide diazinon, 10%). None of these chemicals has previously been detected in human teeth. Molars from the two oldest subjects contained the largest concentrations of MEHP, TCPy, and IMPy. Potentially protective fatty acids detected by gas chromatography/mass spectrometry after derivatization include docosahexaenoic (19%), arachidonic (100%), and linoleic (100%). Validation studies are necessary to verify that each detected chemical in molars provides a biomarker of perinatal exposure.

Comparison of wipe materials and wetting agents for pesticide residue collection from hard surfaces.

Different wipe materials and wetting agents have been used to collect pesticide residues from surfaces, but little is known about their comparability. To inform the selection of a wipe for the National Children's Study, the analytical feasibility, collection efficiency, and precision of Twillwipes wetted with isopropanol (TI), Ghost Wipes (GW), and Twillwipes wetted with water (TW), were evaluated. Wipe samples were collected from stainless steel surfaces spiked with high and low concentrations of 27 insecticides, including organochlorines, organophosphates, and pyrethroids. Samples were analyzed by GC/MS/SIM. No analytical interferences were observed for any of the wipes. The mean percent collection efficiencies across all pesticides for the TI, GW, and TW were 69.3%, 31.1%, and 10.3% at the high concentration, respectively, and 55.6%, 22.5%, and 6.9% at the low concentration, respectively. The collection efficiencies of the TI were significantly greater than that of GW or TW (p<0.0001). Collection efficiency also differed significantly by pesticide (p<0.0001) and spike concentration (p<0.0001). The pooled coefficients of variation (CVs) of the collection efficiencies for the TI, GW, and TW at high concentration were 0.08, 0.17, and 0.24, respectively. The pooled CV of the collection efficiencies for the TI, GW, and TW at low concentration were 0.15, 0.19, and 0.36, respectively. The TI had significantly lower CVs than either of the other two wipes (p=0.0008). Though the TI was superior in terms of both accuracy and precision, it requires multiple preparation steps, which could lead to operational challenges in a large-scale study.

Semivolatile endocrine-disrupting compounds in paired indoor and outdoor air in two northern California communities.

Interest in the health effects of potential endocrine-disrupting compounds (EDCs) that are high production volume chemicals used in consumer products has made exposure assessment and source identification a priority. We collected paired indoor and outdoor air samples in 40 nonsmoking homes in urban, industrial Richmond, CA, and 10 in rural Bolinas, CA. Samples were analyzed by GC-MS for 104 analytes, including phthalates (11), alkylphenols (3), parabens (3), polybrominated diphenyl ether (PBDE) flame retardants (3), polychlorinated biphenyls (PCBs) (3), polycyclic aromatic hydrocarbons (PAHs) (24), pesticides (38), and phenolic compounds (19). We detected 39 analytes in outdoor air and 63 in indoor air. For many of the phenolic compounds, alkylphenols, phthalates, and PBDEs, these represent some of the first outdoor measures and the first analysis of the relative importance of indoor and outdoor sources in paired samples. Data demonstrate higher indoor concentrations for 32 analytes, suggesting primarily indoor sources, as compared with only 2 that were higher outdoors. Outdoor air concentrations were higher in Richmond than Bolinas for 3 phthalates, 10 PAHs, and o-phenylphenol, while indoor air levels were more similar between communities, except that differences observed outdoors were also seen indoors. Indoor concentrations of the most ubiquitous chemicals were generally correlated with each other (4-t-butylphenol, o-phenylphenol, nonylphenol, several phthalates, and methyl phenanthrenes; Kendall correlation coefficients 0.2-0.6, p<0.05), indicating possible shared sources and highlighting the importance of considering mixtures in health studies.

Development of a personal dual-phase air sampling method for phthalate diesters.

Phthalates are used as plasticizers in many industrial and consumer products. Urinary biomonitoring has shown widespread human exposure to phthalates, with workers having especially high exposures. Phthalates can be present in workplace air as either aerosols or vapors depending on source materials, vapor pressure, and processing temperatures. We sought to develop a dual-phase air sampling method for 6 phthalates, dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), benzyl butyl phthalate (BzBP), di(2-ethylhexyl) phthalate (DEHP), and di-n-octyl phthalate (DnOP), adaptable to aerosol inlets with known particle collection characteristics. Collection media consisted of a quartz fiber filter and XAD-2 resin. Limit of detection (LOD) and limit of quantification (LOQ) were determined for each phthalate. Phthalate recoveries were evaluated at 3x, 10x and 30x the LOQ, and after storage at -21 degrees C and 21 degrees C. Media were Soxhlet extracted in 10% diethyl ether in hexanes along with an extraction surrogate, di-n-pentyl phthalate-d(4). Gas chromatography/mass spectrometry was performed to quantify the phthalate diesters using di(2-ethylhexyl) phthalate-d(4) as an internal standard. Estimated LODs were 1 microg per sample (BzBP, DEHP, and DnOP), 2 microg per sample (DMP and DBP), and 5 microg per sample (DEP). Mean recoveries under static conditions were 85-104% for DBP, BzBP, DEHP, and DnOP; but <70% for DMP and DEP at 3x and 10x the LOQ. After air was pulled through spiked samples, DMP and DEP recoveries improved to 74-81%. After storage for 62 days, phthalate recovery was better at -21 degrees C than at 21 degrees C. Method accuracy was best for DBP, BzBP, DEHP, and DnOP (range 11-18%), and less so for DMP (28%) and DEP (29%).

Androgenic and estrogenic activity in water bodies receiving cattle feedlot effluent in Eastern Nebraska, USA.

Studies reveal that surface waters worldwide are contaminated with hormonally active agents, many released from sewage treatment plants. Another potential source of aquatic hormonal contamination is livestock feedlot effluent. In this study, we assessed whether feedlot effluent contaminates watercourses by measuring a) total androgenic [methyltrienolone (R1881) equivalents] and estrogenic (17beta-estradiol equivalents) activity using the A-SCREEN and E-SCREEN bioassays and b) concentrations of anabolic agents via gas chromatography-mass spectroscopy and enzyme-based immunoassays. Water samples were collected over 3 years from up to six sites [all confluent with the Elkhorn River, Nebraska, USA: a feedlot retention pond (site 1), a site downstream from site 1 (site 2), a stream with intermediate livestock impact (site 3), and three sites with no observable livestock impact (sites 4-6)] and two sources of tap water. In 1999, samples from site 1 contained 9.6 pM R1881 equivalents and 1.7 pM 17beta-estradiol equivalents. Site 2 samples had estrogen levels similar to those in site 1 samples but lower androgen levels (3.8 pM R1881 equivalents). Androgen levels in site 3 samples were similar to those in site 2 samples, whereas estrogen levels decreased to 0.7 pM 17beta-estradiol equivalents. At site 6, androgen levels were approximately half those found at site 3, and estrogen levels were comparable with those at site 3. Sampling in later years was limited to fewer sites because of drought and lack of permission to access one site. Instrumental analysis revealed estrone but no significant levels of resorcylic acid lactones or trenbolone metabolites. Tap water was devoid of hormonal activity. We conclude that feedlot effluents contain sufficient levels of hormonally active agents to warrant further investigation of possible effects on aquatic ecosystem health.

Agricultural and residential pesticides in wipe samples from farmworker family residences in North Carolina and Virginia.

Children of farmworkers can be exposed to pesticides through multiple pathways, including agricultural take-home and drift as well as residential applications. Because farmworker families often live in poor-quality housing, the exposure from residential pesticide use may be substantial. We measured eight locally reported agricultural pesticides and 13 pesticides commonly found in U.S. houses in residences of 41 farmworker families with at least one child < 7 years of age in western North Carolina and Virginia. Wipe samples were taken from floor surfaces, toys, and children's hands. We also collected interview data on possible predictors of pesticide presence, including characteristics of the household residents, cleaning practices, and characteristics of the home. All families were Spanish-speaking, primarily from Mexico. Results indicate that six agricultural and 11 residential pesticides were found in the homes, with agricultural, residential, or both present in 95% of homes sampled. In general, residential pesticides were more commonly found. Presence of both types of pesticides on the floor was positively associated with detection on toys or hands. Agricultural pesticide detection was associated with housing adjacent to agricultural fields. Residential pesticide detection was associated with houses judged difficult to clean. Although the likelihood of agricultural pesticide exposure has been considered high for farmworker families, these results indicate that residential pesticide use and exposure in this population merit further study.