Quantifying MCPA load pathways at catchment scale using high temporal resolution data.

Detection of the agricultural acid herbicide MCPA (2-methyl-4-chlorophenoxyacetic acid) in drinking water source catchments is of growing concern, with economic and environmental implications for water utilities and wider ecosystem services. MCPA is poorly adsorbed to soil and highly mobile in water, but hydrological pathway processes are relatively unknown at the catchment scale and limited by coarse resolution data. This understanding is required to target mitigation measures and to provide a framework to monitor their effectiveness. To address this knowledge gap, this study reports findings from river discharge and synchronous MCPA concentration datasets (continuous 7 hour and with additional hourly sampling during storm events) collected over a 7 month herbicide spraying season. The study was undertaken in a surface (source) water catchment (384 km2-of which 154 km2 is agricultural land use) in the cross-border area of Ireland. Combined into loads, and using two pathway separation techniques, the MCPA data were apportioned into event and baseload components and the former was further separated to quantify a quickflow (QF) and other event pathways. Based on the 7 hourly dataset, 85.2 kg (0.22 kg km-2 by catchment area, or 0.55 kg km-2 by agricultural area) of MCPA was exported from the catchment in 7 months. Of this load, 87.7 % was transported via event flow pathways with 72.0 % transported via surface dominated (QF) pathways. Approximately 12 % of the MCPA load was transported via deep baseflows, indicating a persistence in this delayed pathway, and this was the primary pathway condition monitored in a weekly regulatory sampling programme. However, overall, the data indicated a dominant acute, storm dependent process of incidental MCPA loss during the spraying season. Reducing use and/or implementing extensive surface pathway disconnection measures are the mitigation options with greatest potential, the success of which can only be assessed using high temporal resolution monitoring techniques.

SARS CoV-2 seroprevalence in a US school district during COVID-19.

Reduced symptomatology and access to testing in children have led to underestimates of paediatric COVID-19 prevalence and raised concerns about school safety. To explore COVID-19 prevalence and risk factors in school settings, we conducted a SARS-CoV-2 serosurvey in a Vermont, USA school district in December 2020. Among 336 students (63%) and 196 teachers/staff (37%), adjusted seroprevalence was 4.7% (95% CI 2.9 to 7.2) and was lowest in preK-5 students (4-10 Years). Seroprevalence was 10-fold higher than corresponding state PCR data but was low overall with no evidence of onward transmissions. These results further support feasibility of in-person learning during COVID-19 with appropriate mitigation measures.

Geographical variation in infant mortality, stillbirth and low birth weight in Northern Ireland, 1992-2002.

BACKGROUND: Improving the health of expectant mothers and reductions in health inequalities, are repeatedly prioritised in policy reports in England and Northern Ireland. Measurement of underlying rates, and geographical variation in rates, of adverse birth outcomes are tools in monitoring these priorities. METHODS: Northern Ireland data on stillbirths, infant mortality and low birth weight (1992-2002) were linked to board (n=4), district council (n=26) and 1991 census wards (n=568). Underlying variations in rates were estimated at each geographical level, unadjusted and controlling for year, ward-level deprivation, settlement size and higher geographical levels. Impacts on geographical variation of individual social class, maternal age, multiple birth and smoking were assessed. RESULTS: There was significant variation in underlying rates of low birth weight (<2500 g) at all three geographical levels. Controlling for smoking reduced variation between wards. Geographical variation proved more robust for medium than for very low birth weight. No variation was seen between boards for other outcomes, nor between district level rates of infant mortality. Evidence was weak for variation in district rates of neonatal deaths and stillbirths, and variation in ward-level adjusted stillbirth rates was not significant. Variation in ward-level infant death rates was robust to all adjustments, with risks tripling (infant mortality) or quadrupling (neonatal mortality) between the 10th and 90th percentile. CONCLUSIONS: Strong evidence was found of geographical variation in infant mortality and low birth weight, unexplained by individual risk factors or by area-level deprivation. Geographical targeting or area-level interventions might look beyond deprivation scores, to other environmental and social factors.