Results of WEPAL-QUASIMEME/NORMANs first global interlaboratory study on microplastics reveal urgent need for harmonization.

To survey the conformity and quality of results among laboratories for microplastics determination worldwide, an international laboratory intercomparison and development exercise was organized. The 34 participants were requested to determine the polymer type and number or mass of polymer particles in 12 samples, i.e. six samples containing of pre-production pellets, five dissolvable soda tablets containing different (smaller) polymer particles and one blank soda tablet. A novel method for providing the test materials in aluminium strips was used. Thirty laboratories (88%) submitted data using their own method of choice, resulting in a variety of identification and quantification methods (n = 7). The majority of the labs (53-100%) correctly identified the type of polymer in all samples but one. The performance of the laboratories in quantifying and weighing the pellets was very good. The analysis of the number of the particles in the soda tablets varied considerably between laboratories (29-91%). The results of this study highlight the complexity of microplastics analysis and the need for harmonization of both reporting format and methods. Continued development and assessment of the comparability among analytical methods and laboratories are urgently needed to support monitoring programmes, research and decision-making.

COVID-19 in critically ill patients in North Brabant, the Netherlands: Patient characteristics and outcomes.

PURPOSE: Since the SARS-CoV-2 pandemic, countries are overwhelmed by critically ill Coronavirus disease 2019 (COVID-19) patients. As ICU capacity becomes limited we characterized critically ill COVID-19 patients in the Netherlands. METHODS: In this case series, COVID-19 patients admitted to the ICU of the Jeroen Bosch Hospital were included from March 9 to April 7, 2020. COVID-19 was confirmed by a positive result by a RT-PCR of a specimen collected by nasopharyngeal swab. Clinical data were extracted from medical records. RESULTS: The mean age of the 50 consecutively included critically ill COVID-19 patients was 65 ± 10 years, the mean BMI was 29 ± 4.7 and 66% were men. Seventy-eight percent of patients had ≥1 comorbidity, 34% had hypertension. Ninety-six percent of patients required mechanical ventilation and 80% were ventilated in prone position. Venous thromboembolism was recognized in 36% of patients. Seventy-four percent of patients survived and were successfully discharged from the ICU, the remaining 26% died (median follow up 86 days). The length of invasive ventilation in survivors was 15 days (IQR 12-31). CONCLUSIONS: The survival rate of COVID-19 critically ill patients in our population is considerably better than previously reported. Thrombotic complications are commonly found and merit clinical attention. TRIAL REGISTRATION NUMBER: NL2020.07.04.01.

The underlying challenges that arise when analysing short-chain chlorinated paraffins in environmental matrices.

As short-chain chlorinated paraffins (SCCPs) are listed on several monitoring programs, validated methods are essential. However, their complexity and the lack of commercially available certified reference materials (RMs) hinder a proper validation of methods. Instead, one method is usually 'validated' by evaluating performances and results of spiked materials with that of one other method, which could easily lead to unreliable results. This study evaluated four analytical methods with different principles (i.e. comprehensive two dimensional GC coupled to a micro electron capture detector, developed for this study, chloride enhanced atmospheric pressure chemical ionization triple quadrupole time of flight MS (APCI-QToF-HRMS), GC coupled to an electron capture negative ion low resolution MS (GC-ECNI-LRMS) and carbon skeleton GC-MS), investigated the comparability in SCCP determination in spiked and naturally contaminated samples and determined SCCP amounts in candidate RMs for possible certification. The results cast doubt on the use of the most commonly applied method (i.e. GC-ECNI-LRMS), as well as using spiked materials for method validation. The APCI-QToF-HRMS method was found most promising as it achieves the required MS resolution (>21,000), is relatively fast and can detect also other CPs. The suitable identified SCCP levels in the candidate RMs and the agreement in results between the methods bring the first certification of a RM for SCCPs within reach.

Melanocortin-1 receptor variant R151C modifies melanoma risk in Dutch families with melanoma.

Germline mutations of the cell-cycle regulator p16 (also called "CDKN2A") in kindreds with melanoma implicate this gene in susceptibility to malignant melanoma. Most families with familial atypical multiple-mole melanoma (FAMMM) who are registered at the Leiden dermatology clinic share the same p16-inactivating deletion (p16-Leiden). Incomplete penetrance and variable clinical expression suggest risk modification by other genetic and/or environmental factors. Variants of the melanocortin-1 receptor (MC1R) gene have been shown to be associated with red hair, fair skin, and melanoma in humans. Carriers of the p16-Leiden deletion in Dutch families with FAMMM show an increased risk of melanoma when they also carry MC1R variant alleles. The R151C variant is overrepresented in patients with melanoma who are from families with the p16-Leiden mutation. Although some of the effect of the R151C variant on melanoma risk may be attributable to its effect on skin type, our analyses indicate that the R151C variant contributes an increased melanoma risk even after statistical correction for its effect on skin type. These findings suggest that the R151C variant may be involved in melanoma tumorigenesis in a dual manner, both as a determinant of fair skin and as a component in an independent additional pathway.