Monthly Archives: February 2012

Should WHO restore the manganese guideline?

These authors argue that the World Health Organization (WHO) should restore and lower the guideline for manganese…..well perhaps. It seems that WHO guidelines may not be the authoritative source on drinking water quality……the abstract is below. Click here for a prepublication copy of the paper.

Frisbie SH, Mitchell EJ, Dustin H, Maynard DM, Sarkar B 2012. World Health Organization Discontinues Drinking Water Guideline for Manganese. Environ Health Perspect.  http://dx.doi.org/10.1289/ehp.1104693

Background: The World Health Organization (WHO) released the 4th edition of Guidelines for Drinking-water Quality in July, 2011. In this edition, the 400 µg/L drinking water guideline for manganese (Mn) was discontinued with the assertion that since “this health-based value is well above concentrations of manganese normally found in drinking-water, it is not considered necessary to derive a formal guideline value.”

Objectives: This paper reviews the WHO drinking water guideline for Mn, from its introduction in 1958 through its discontinuation in 2011.

Methods: We used WHO publications documenting the guidelines as primary references. We identified countries with drinking water or potential drinking water supplies exceeding 400 µg/L of Mn from peer reviewed journal articles, government reports, published conference proceedings, and theses. We summarized the health effects of Mn from peer reviewed journal articles.

Discussion: Drinking water or potential drinking water supplies with Mn concentrations above 400 µg/L are found in a substantial number of countries worldwide. The drinking water of many tens of millions of people has Mn concentrations above 400 µg/L. Recent research on health effects of Mn suggests that the earlier 400 µg/L WHO guideline may have been too high to adequately protect public health.

Conclusions: The toxic effects and geographic distribution of Mn in drinking water supplies justify a re-evaluation by the WHO of its decision to discontinue its Mn drinking water guideline.

 

 

Persistent organic pollutants (POPs) generally higher in China than other countries

Bao, L.J., K.A. Maruya, S.A. Snyder, and E.Y. Zeng. China’s water pollution by persistent organic pollutants. Environ Pollut. 2012 Apr;163:100-8. Epub  2012 Jan 11.

State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; Graduate School, Chinese Academy of Sciences, Beijing 100049, China.

Available data were reviewed to assess the status of contamination by persistent organic pollutants (POPs), including organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs), perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA), in drinking water sources and coastal waters of China. The levels of POPs in China’s waters were generally at the high end of the global range. A comparison of China’s regulatory limits indicated that PCBs in rivers and coastal water may pose potential human health risk. Occurrence of DDTs in some rivers of China may also pose health risk to humans using the regulatory limits of DDTs recommended by the European Union. Future monitoring of POPs in China’s waters should be directed towards analytes of concern (e.g. PCBs and PCDD/Fs) and to fill data gaps for analytes (e.g. PBDEs, PCDD/Fs, and chlordane) and in watersheds/regions (e.g. West China) where data are scarce.

Research: Assimilable organic carbon (AOC) precursors contribute to AOC formation in distributed water

Ohkouchi, Y., B.T. Ly, S. Ishikawa, Y. Aoki, S. Echigo, and S. Itoh. A survey on levels and seasonal changes of assimilable organic carbon (AOC) and its precursors in drinking water. Environ Technol. 2011 Oct;32(13-14):1605-13.

Graduate School of Global Environmental Studies, Kyoto University, Kyoto, Japan. yohkouchi@urban.env.kyoto-u.ac.jp

In Japan, customers’ concerns about chlorinous odour in drinking water have been increasing. One promising approach for reducing chlorinous odour is the minimization of residual chlorine in water distribution, which requires stricter control of organics to maintain biological stability in water supply systems. In this investigation, the levels and seasonal changes of assimilable organic carbon (AOC) and its precursors in drinking water were surveyed to accumulate information on organics in terms of biological stability. In tap water samples purified through rapid sand filtration processes, the average AOC concentration was 174 microgC/L in winter and 60 microgC/L in summer. This difference seemed to reflect the seasonal changes of AOC in the natural aquatic environment. On the other hand, very little or no AOC could be removed after use of an ozonation-biological activated carbon (BAC) process. Especially in winter, waterworks should pay attention to BAC operating conditions to improve AOC removal. The storage of BAC effluent with residual chlorine at 0.05-0.15 mgCl2/L increased AOC drastically. This result indicated the possibility that abundant AOC precursors remaining in the finished water could contribute to newly AOC formation during water distribution with minimized residual chlorine. Combined amino acids, which remained at roughly equivalent to AOC in finished water, were identified as major AOC precursors. Prior to minimization of residual chlorine, enhancement of the removal abilities for both AOC and its precursors would be necessary.

Arsenic study raises more questions than answers….

Confidence intervals are not reported in the abstract. A typical ecological study that is not definitive…..

Gong, G., and S.E. Bryant. Low-level arsenic exposure, AS3MT gene polymorphism and cardiovascular diseases in rural Texas counties. Environ Res. 2012 Feb 15.

Abstract: Most Americans living in rural areas use groundwater for drinking. Exposure to low-level (around the current U.S. standard 10μg/L) arsenic in drinking water is associated with increased mortality of cardiovascular diseases. The current study was to determine if coronary heart disease, hypertension, and hyperlipidemia were associated with low-level arsenic exposure and AS3MT gene single nucleotide polymorphism (SNP) A35991G (rs10748835) in rural Texas. Subjects (156 men, 343 women, 40-96 years of age with a mean of 61) were residents from rural counties Cochran, Palmer, and Bailey, Texas. Groundwater arsenic concentration at each subject’s home was estimated with ArcGIS inverse distance weighted interpolation based on the residential location’s distances to surrounding wells with known water arsenic concentrations. The estimated groundwater arsenic concentration ranged from 2.2 to 15.3 (mean 6.2)μg/L in this cohort. Logistic regression analysis showed that coronary heart disease was associated with higher arsenic exposure (p<0.05) and with AS3MT genotype GG vs. AA (p<0.05) after adjustments for age, ethnicity, gender, education, smoking status, alcoholism, and anti-hyperlipidemia medication. Hypertension was associated with higher arsenic exposure, while hyperlipidemia was associated with genotype AG vs. AA of the AS3MT gene (p<0.05). Thus, coronary heart disease and its main risk factors were associated with low-level arsenic exposure, AS3MT polymorphism or both.

Click here for the article (fee).

Membrane bioreactor removes pharmaceuticals and antibiotics

Schröder, HF, Tambosi, JL, Sena, RF, Moreira, RF, José, HJ, Pinnekamp, J. The removal and degradation of pharmaceutical compounds during membrane bioreactor treatment. Water Sci Technol. 2012;65(5):833-9.

Institute of Environmental Engineering, RWTH Aachen University, Aachen, Germany E-mail: hf.schroeder@post.rwth-aachen.de

Abstract: Pharmaceutical compounds such as non-steroidal anti-inflammatory drugs (NSAIDs) and antibiotics have been detected in sewage treatment plant (STP) effluents, surface and ground water and even in drinking water all over the world, and therefore have developed as compounds of concern. Membrane bioreactor (MBR) treatment has gained significant popularity as an advanced wastewater treatment technology and might be effective for an advanced removal of these pollutants. This paper evaluates the treatment of wastewater containing three NSAIDs (acetaminophen, ketoprofen and naproxen) and three antibiotics (roxithromycin, sulfamethoxazole and trimethoprim) performed in two MBRs with sludge retention times (SRTs) of 15 (MBR-15) and 30 (MBR-30) days over a period of four weeks. It was observed that NSAIDs were removed with higher efficiencies than the antibiotics for both MBRs, and the MBR-30 presented higher removal efficiencies for all the compounds than obtained by MBR-15. Removal rates ranged from 55% (sulfamethoxazole) up to 100% (acetaminophen, ketoprofen). Besides mineralisation biological transformation products of ketoprofen and naproxen produced by wastewater biocoenosis were identified in both MBR permeates using liquid chromatography coupled with mass spectrometry (LC-MS). The results indicated the importance of investigating the environmental fate of pharmaceuticals and their transformation products reaching the environment.

Hellwig and Lennon 2004: Systemic versus topical fluoride

Hellwig, E. and A.M. Lennon. Systemic versus topical fluoride. Caries Res. 2004 May-Jun;38(3):258-62.

Department of Operative Dentistry and Periodontology, Dental Clinic and Dental School, Albert Ludwigs University Freiburg, Freiburg, Germany. hellwig@zmk2.ukl.uni-freiburg.de

Abstract: The actual mechanism of fluoride action is still a subject of debate. A dogma has existed for many decades, that fluoride has to be ingested and acts mainly pre-eruptively. However, recent studies concerning the systemic effect of fluoride supplementation concluded that the caries-preventive effect of fluoride is almost exclusively posteruptive. Moreover, epidemiologists have cast doubt on the validity of the ‘old’ studies dealing with fluoride use. The concept of the posteruptive fluoride effect is supported by in vitro and in situ investigations demonstrating that the mode of action of fluoride can be attributed mainly to its influence on de- and remineralization kinetics of dental hard tissues. Therefore, topical fluoride application (e.g. in the form of fluoridated dentifrices) should be encouraged. There are still important questions open that need to be answered despite existing knowledge about the caries-preventive effect of fluoride.

Click here for the full paper (free).

Richard Lindzen: “…the increase in CO2 will lead to very little warming…”

“The evidence is that the increase in CO2 will lead to very little warming, and that the connection of this minimal warming (or even significant warming) to the purported catastrophes is also minimal. The arguments on which the catastrophic claims are made are extremely weak – and commonly acknowledged as such. They are sometimes overtly dishonest.”

Click here or image below for the full presentation.