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Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has infected more than 35 million people globally, with more than 1 million deaths recorded by WHO as of Oct 12, 2020. As a second wave of COVID-19 affects Europe, and with winter approaching, we need clear communication about the risks posed by COVID-19 and effective strategies to combat them. Here, we share our view of the current evidence-based consensus on COVID-19.

Summary Background Hurricane Maria struck Puerto Rico on Sept 20, 2017, devastating the island. Controversy surrounded the official death toll, fuelled by estimates of excess mortality from academics and investigative journalists. We analysed all-cause excess mortality following the storm. Methods We did a time-series analysis in Puerto Rico from September, 2017, to February, 2018. Mortality data were from the Puerto Rico Vital Statistics System. We developed two counterfactual scenarios to establish the population at risk. In the first scenario, the island's population was assumed to track the most recent census estimates. In the second scenario, we accounted for the large-scale population displacement. Expected mortality was projected for each scenario through over-dispersed log-linear regression from July, 2010, to August, 2017, taking into account changing distributions of age, sex, and municipal socioeconomic development, as well as both long-term and seasonal trends in mortality. Excess mortality was calculated as the difference between observed and expected deaths. Findings Between September, 2017, and February, 2018, we estimated that 1191 excess deaths (95% CI 836–1544) occurred under the census scenario. Under the preferred displacement scenario, we estimated that 2975 excess deaths (95% CI 2658–3290) occurred during the same observation period. The ratio of observed to expected mortality was highest for individuals living in municipalities with the lowest socioeconomic development (1·43, 95% CI 1·39–1·46), and for men aged 65 years or older (1·33, 95% CI 1·30–1·37). Excess risk persisted in these groups throughout the observation period. Interpretation Analysis of all-cause mortality with vital registration data allows for unbiased estimation of the impact of disasters associated with natural hazards and is useful for public health surveillance. It does not depend on certified cause of death, the basis for the official death toll in Puerto Rico. Although all sectors of Puerto Rican society were affected, recovery varied by municipal socioeconomic development and age groups. This finding calls for equitable disaster preparedness and response to protect vulnerable populations in disasters. Funding Forensic Science Bureau, Department of Public Safety, and Milken Institute School of Public Health of The George Washington University (Washington, DC, USA).

Prior studies addressing associations between mercury and blood pressure have produced inconsistent findings; some of this may result from measuring total instead of speciated mercury. This cross-sectional study of 263 pregnant women assessed total mercury, speciated mercury, selenium, and n-3 polyunsaturated fatty acids in umbilical cord blood and blood pressure during labor and delivery. Models with a) total mercury or b) methyl and inorganic mercury were evaluated. Regression models adjusted for maternal age, race/ethnicity, prepregnancy body mass index, neighborhood income, parity, smoking, n-3 fatty acids and selenium. Geometric mean total, methyl, and inorganic mercury concentrations were 1.40 μg/L (95% confidence interval: 1.29, 1.52); 0.95 μg/L (0.84, 1.07); and 0.13 μg/L (0.10, 0.17), respectively. Elevated systolic BP, diastolic BP, and pulse pressure were found, respectively, in 11.4, 6.8, and 19.8% of mothers. In adjusted multivariable models, a one-tertile increase of methyl mercury was associated with 2.83 mmHg (0.17, 5.50) higher systolic blood pressure and 2.99 mmHg (0.91, 5.08) higher pulse pressure. In the same models, an increase of one tertile of inorganic mercury was associated with a -1.18 mmHg (-3.72, 1.35) lower systolic blood pressure and -2.51 mmHg (-4.49, -0.53) lower pulse pressure. No associations were observed with diastolic pressure. There was a non-significant trend of higher total mercury with higher systolic blood pressure. We observed a significant association of higher methyl mercury with higher systolic and pulse pressure, yet higher inorganic mercury was significantly associated with lower pulse pressure. These results should be confirmed with larger, longitudinal studies.

The practice of environmental health is concerned with the protection of the community. There are a number of tools used for assessment of environmental hazards, but environmental health is most reliant on the use of risk assessment. Risk assessment is a set of tools used to assess hazards on a community level, based on human studies, ecological studies, or toxicity testing of animals.

PCDD and PCDF measurements were made on selected retail milk products, including paper packaged milk samples, covering all known paper carton suppliers in the state of California during 1989. Significant levels of 2,3,7,8 tetrachlorodibenzofuran (TCDF) and 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD) were found in the paper packaged milk in all brands investigated except one. All other 2,3,7,8 substituted PCDFs and PCDDs were either not detected or detected at very low levels. Two non 2,3,7,8 substituted TCDFs were consistently detected in the contaminated milk samples. Using the mean concentration of 2,3,7,8 TCDF and TCDD detected and assuming a 480 ml daily consumption of milk for an adult, we estimated that the milk represented an additional 2.3 pg/kg/day of TCDD equivalent exposure based on the California toxic equivalence (CA TE), but only a 0.56 pg/kg/day increase using the International TE (ITE). The lifetime cancer risk was calculated to be 470 10 6 (CA TE) and 80 10 6 (ITE). Monitoring of retail milk products continued during 1990 but 2,3,7,8 TCDD and 2,3,7,8 TCDF were either not detected or detected at very low levels in all products investigated.

Controlled exposure studies under laboratory and field conditions have been initiated to investigate the biotransfer and bioaccumulation of PCDD/Fs in soil, at low concentrations, to animals which have contact with soil. The chicken was chosen as a model for grazing animals. The accumulation over time of specific isomers is being tracked in eggs, blood, feces, liver, adipose, and edible flesh. Measurable increases of PCDD/F concentration in eggs of exposed chickens, as compared to controls, were seen after 30 days of exposure. The exposure characterization, as well as data on isomer specific biotransfer and bioaccumulation rates in eggs are discussed.

Additional data have been obtained which relate the bioaccumulation of polychlorodibenzodioxins and polychlorodibenzofurans (PCDDs and PCDFs) in foraging chickens to the ingestion of soil contaminated at the low part per trillion (ppt) level. These new data indicate that both the concentration and congener profiles of PCDDs and PCDFs in eggs and body tissues, are correlated with the PCDD and PCDF concentration and congener profile seen in soil on which these chickens were grazing. Additionally, a cow grazing in these areas of low soil PCDD/PCDF contamination showed characteristic PCDD and PCDF profiles in milk. Breast milk from women living in the area did not show the characteristic PCDD/PCDF contamination. Controlled feeding studies of chickens have been initiated which are designed to demonstrate the transfer of PCDDs and PCDFs from soil to tissue and eggs and to establish the kinetics and equilibrium concentrations of the bioaccumulation. Levels and patterns of PCDDs and PCDFs in tissues and eggs from foraging animals appear to be closely related to the levels and patterns in the soils to which they are exposed. This suggests the possibility of animals functioning as sensitive biomonitors for low level soil contamination. In addition, if such animals are used for food, the possibility of human exposure to PCDDs and PCDFs must be considered.

We studied dioxin levels in residents of two California households where dioxin contaminated homegrown eggs and beef were found, in order to determine the level of exposure to dioxins. Risk assessments for carcinogenicity and reproductive toxicity showed that theoretical risks exceeded proscribed regulatory levels. Advisory guidelines were issued about consumption of eggs, chicken and beef. Serum samples from exposed and matched rural comparison subjects were analyzed and preliminary dioxin data show statistically significant elevations of 2,3,7,8-penta and hexa dioxin isomers for both homes. Comparison subjects from rural California had lower serum dioxin levels than those previously reported for Missouri and Sweden. Adipose tissue from a resident of one of the homes was tested for dioxins. The resident died six months later and a post mortem retesting of adipose and testing of liver and lung tissues for dioxins was done. No unusual dioxin levels were found; levels of dioxin in adipose remained stable despite six months of not eating contaminated produce. Dioxins were not a contributing cause of death. In this study, dioxin contaminated eggs and beef have elevated 2,3,7,8-tetra, penta and hexa dioxin levels in serum. The ongoing investigation will seek to delineate the source and extent of contamination, and to determine the extent of the exposed population and potential health impacts.

Studies carried out in California, following a fire which involved a pentachlorophenol wood treatment plant have indicated that low concentrations of dioxins and furans in soil can lead to bioaccumulation in chickens and cattle which are in contact with the soil. These compounds were found to distribute into various tissues of the animals and into the eggs of the chickens. A significant change in congener profile and isomer pattern was seen when comparing soils to tissues. Source tests of local incinerators showed quite different congener profile than was seen in soils. Concentrations found in animal products used as food suggest the possibility of excessive human exposure based on modest consumption assumptions.