Daily Archives: November 1, 2014

Uranium in Small Water Systems, Schleswig-Holstein, Germany

Ostendorp G. [Uranium Concentration in Drinking Water from Small-scale Water Supplies in Schleswig-Holstein, Germany.] Gesundheitswesen. 2014 Oct 30. [Article in German]

In this study the drinking water of 212 small-scale water supplies, mainly situated in areas with intensive agriculture or fruit-growing, was analysed for uranium. The median uranium concentration amounted to 0.04 µg/lL, the 95th percentile was 2.5 µg/L. The maximum level was 14 µg/L. This sample exceeded the guideline value for uranium in drinking water. The uranium concentration in small-scale water supplies was found to be slightly higher than that in central water works in Schleswig-Holstein. Water containing more than 10 mg/L nitrate showed significantly higher uranium contents. The results indicate that the uranium burden in drinking water from small wells is mainly determined by geological factors. An additional anthropogenic effect of soil management cannot be excluded. Overall uranium concentrations were low and not causing health concerns. However, in specific cases higher concentrations may occur.

Violent Tornadoes on the Decline in the United States?

Good post examining US tornado frequency, the graph below, as well as other plots is here.

torngraph_thumb1

Lefsrud and Meyer Study on “Climate Change” Discourse Too Simplistic

This is a long article on an interesting topic. However, after quickly reading it the analysis strikes me as being a bit too simplistic. Focusing on framing and perception in the absence of clear definition and meaning of terms between the groups (as well as a lack of definition from these authors) results in an analysis that wanders through a muddy-middle wilderness only to emerge with little to say about the underlying differences between professionals on climate issues. As I’ve said many times, there is no neutrality when it comes to data interpretation, and this is true of the data in this paper as well. The authors have certainly put a lot of effort into their study and it may serve to help clarify differences. We shall see what effect, if any, the study has on climate discussions. 

Lianne M. Lefsrud, Renate E. Meyer. Science or Science Fiction? Professionals’ Discursive Construction of Climate Change. Organization Studies 2012 33: 1477DOI: 10.1177/0170840612463317

This paper examines the framings and identity work associated with professionals’ discursive construction of climate change science, their legitimation of themselves as experts on ‘the truth’, and their attitudes towards regulatory measures. Drawing from survey responses of 1077 professional engineers and geoscientists, we reconstruct their framings of the issue and knowledge claims to position themselves within their organizational and their professional institutions. In understanding the struggle over what constitutes and legitimizes expertise, we make apparent the heterogeneity of claims, legitimation strategies, and use of emotionality and metaphor. By linking notions of the science or science fiction of climate change to the assessment of the adequacy of global and local policies and of potential organizational responses, we contribute to the understanding of ‘defensive institutional work’ by professionals within petroleum companies, related industries, government regulators, and their professional association.

Click here for full paper (Open Source).

 

Groundwater Arsenic in New Hampshire and Adverse Birth Outcomes

I have recently commented on another geospatial study that such studies are not very informative (athough they get a paper published). Why? Because attribution cannot be assigned with this analytical protocol.

The reason given to support such use of geospatial information is that it simply mimics the effort John Snow and the Broad Street Well. Snow did it so why can’t we do it?

Snow marked on a map the deaths due to cholera in England and used this geospatial information to identify the contaminated well on Broad Street. But this comparison is invalid. Snow was counting real dead people at a specific location (to be blunt about it) and not using computer models to try to find where the fatalities might be. In other words, Snow was using hard data of physical location perfectly correlated with fatalities, not computer model projections.

If enough assumptions are made computer modeling studies fall into the trap of simply concluding what has already been assumed from the beginning of the study. No one wants to see adverse birth outcomes at any time. But attribution to drinking water arsenic as the cause of these effects is not supported by this study and potentially points in the wrong direction.  Yet activists and overzealous regulators will do just that to sound an alarm (usually for fund raising). Focusing so much on drinking water is once again taking a rabbit trail that leads to nowhere. This is counterproductive to public health. Why not use this study to generate hypotheses to examine factors other than drinking water arsenic that might be suggested by the geospatial data analysis? If such metadata was not collected or available, then the study is inadequate indeed. 

Shi X, Ayotte JD, Onda A, Miller S, Rees J, Gilbert-Diamond D, Onega T, Gui J, Karagas M, Moeschler J. Geospatial association between adverse birth outcomes and arsenic in groundwater in New Hampshire, USA. Environmental geochemistry and health. 2014 Oct 19.

There is increasing evidence of the role of arsenic in the etiology of adverse human reproductive outcomes. Because drinking water can be a major source of arsenic to pregnant women, the effect of arsenic exposure through drinking water on human birth may be revealed by a geospatial association between arsenic concentration in groundwater and birth problems, particularly in a region where private wells substantially account for water supply, like New Hampshire, USA. We calculated town-level rates of preterm birth and term low birth weight (term LBW) for New Hampshire, by using data for 1997-2009 stratified by maternal age. We smoothed the rates by using a locally weighted averaging method to increase the statistical stability. The town-level groundwater arsenic probability values are from three GIS data layers generated by the US Geological Survey: probability of local groundwater arsenic concentration >1 µg/L, probability >5 µg/L, and probability >10 µg/L. We calculated Pearson’s correlation coefficients (r) between the reproductive outcomes (preterm birth and term LBW) and the arsenic probability values, at both state and county levels. For preterm birth, younger mothers (maternal age <20) have a statewide r = 0.70 between the rates smoothed with a threshold = 2,000 births and the town mean arsenic level based on the data of probability >10 µg/L; for older mothers, r = 0.19 when the smoothing threshold = 3,500; a majority of county level r values are positive based on the arsenic data of probability >10 µg/L. For term LBW, younger mothers (maternal age <25) have a statewide r = 0.44 between the rates smoothed with a threshold = 3,500 and town minimum arsenic concentration based on the data of probability >1 µg/L; for older mothers, r = 0.14 when the rates are smoothed with a threshold = 1,000 births and also adjusted by town median household income in 1999, and the arsenic values are the town minimum based on probability >10 µg/L. At the county level for younger mothers, positive r values prevail, but for older mothers, it is a mix. For both birth problems, the several most populous counties-with 60-80 % of the state’s population and clustering at the southwest corner of the state-are largely consistent in having a positive r across different smoothing thresholds. We found evident spatial associations between the two adverse human reproductive outcomes and groundwater arsenic in New Hampshire, USA. However, the degree of associations and their sensitivity to different representations of arsenic level are variable. Generally, preterm birth has a stronger spatial association with groundwater arsenic than term LBW, suggesting an inconsistency in the impact of arsenic on the two reproductive outcomes. For both outcomes, younger maternal age has stronger spatial associations with groundwater arsenic.

The paper is here.

Biomarkers are Inadequate Proxy for Drinking Water Contaminant Exposures

Various biomarkers have been proposed over the years as indicators of exposure to drinking water contaminants (e.g. arsenic in hair, toenails, etc.). Determing the exact cause of the biomarker change is very difficult if not impossible given the complexity of the human body biochemistry and various sources of exposure (e.g., inhalation, ingestion of water, intake of food, vitamins, consumer products used on or reaching the skin). Biomarkers will be useful for certain applications (e.g. indicator of overall body burden) but as a proxy for contaminant exposure via drinking water it is inadequate. Not being able (at least at this time) to directly correlate a particular drinking water contaminant exposure directly to a particular biomarker change without significant confounding is a fatal flaw if such biomarker data is used in drinking water epidemiology studies.

Ab Razak NH, Praveena SM, Hashim Z. Toenail as a biomarker of heavy metal exposure via drinking water: a systematic review. Reviews on environmental health, 2014 Oct 21. pii: /j/reveh.ahead-of-print/reveh-2014-0063/reveh-2014-0063.xml. doi: 10.1515/reveh-2014-0063.

Toenail is metabolic end product of the skin, which can provide information about heavy metal accumulation in human cells. Slow growth rates of toenail can represent heavy metal exposure from 2 to 12 months before the clipping. The toenail is a non-invasive biomarker that is easy to collect and store and is stable over time. In this systematic review, the suitability of toenail as a long-term biomarker was reviewed, along with the analysis and validation of toenail and confounders to heavy metal. This systematic review has included 30 articles chosen from a total of 132 articles searched from online electronic databases like Pubmed, Proquest, Science Direct, and SCOPUS. Keywords used in the search included “toenail”, “biomarker”, “heavy metal”, and “drinking water“. Heavy metal in toenail can be accurately analyzed using an ICP-MS instrument. The validation of toenail heavy metal concentration data is very crucial; however, the Certified Reference Material (CRM) for toenail is still unavailable. Usually, CRM for hair is used in toenail studies. Confounders that have major effects on heavy metal accumulation in toenail are dietary intake of food and supplement, smoking habit, and overall health condition. This review has identified the advantages and limitations of using toenail as a biomarker for long-term exposure, which can help future researchers design a study on heavy metal exposure using toenail.

Click here for paper (fee).

 

Food Handling Most Likely Cause of Shanghai Boarding School Norovirus Outbreak

When a group of students at a school become sick with gastrointestinal illness the first cause many people think of is the contaminated drinking water. But in the US, contaminated drinking water plays a very minor role compared to food contamination. In this study, food handling practices (lack of hygiene, lack of disinfection of surfaces, asymptomatic food handlers) was identified as the likely cause. 

Xue C, Fu Y, Zhu W, Fei Y, Zhu L, Zhang H, Pan L, Xu H, Wang Y, Wang W, Sun Q. An outbreak of acute norovirus gastroenteritis in a boarding school in Shanghai: a retrospective cohort study. BMC public health. 2014 Oct 22;14(1):1092.

BACKGROUND: More than 200 students and teachers at a boarding school in Shanghai developed acute gastroenteritis in December, 2012. The transmission mode remained largely unknown. An immediate epidemiological investigation was conducted to identify it.

METHODS: Using a retrospective cohort design, we investigated demographic characteristics, school environment, and previous contacts with people who had diarrhea and/or vomiting, drinking water conditions, recalls of food consumption in the school cafeteria, hand-washing habits and eating habits. Rectal swabs of the new cases and food handlers as well as water and food samples were collected to test potential bacteria and viruses. Norovirus was detected by real-time reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS: A total of 278 cases developed gastrointestinal symptoms in this outbreak, and the overall attack rate was 13.9%. The main symptoms included vomiting (50.0%), abdominal cramps (40.3%), nausea (27.0%), diarrhea (6.8%) and fever (6.8%). Twenty rectal swab samples were detected as Norovirus-positive, including 11 from student cases and 9 from asymptomatic food handlers (non-cases). Among environmental surface samples from the kitchen, 8 samples were also detected as Norovirus-positive. The genotypes of viral strains were the same (GII) in patients, asymptomatic food handlers and environmental surfaces. Other samples, including rectal swabs, water samples and food samples were negative for any bacteria and other tested viruses. Asymptomatic food handlers may have contaminated the cooked food during the food preparation.

CONCLUSION: The study detected that the outbreak was caused by Norovirus and should be controlled by thorough disinfection and excluding asymptomatic food handlers from food preparation. Early identification of the predominant mode of transmission in this outbreak was necessary to prevent new cases. Furthermore, good hygiene practices such as regular hand washing and efficient daily disinfection should be promoted to prevent such infection and outbreaks.

Click here for full paper (fee).