Iodo-THM Formation During Chlorination of Source Waters With Naturally Occurring Ammonium and High Sodium Content

The current study investigates the occurrence and specific conditions that favour the formation of iodo-THMs during the disinfection of source waters with elevated sodium content (over 200 mg/L sodium) and naturally occurring ammonium. Based on the previous data, the current study focused on 16 water treatment plants (WTPs) using source waters with sodium content between 10 mg/L and 760 mg/L and naturally occurring ammonium. Source water, treated water and mid-point distribution water samples were collected under both winter and summer conditions. Samples were stabilized, shipped cold, and analysed within 4 days from collection for the six iodo-THMs, using solid phase micro extraction gas chromatography with electron-capture detection (SPME-GC-ECD). Data for 20 other neutral DBPs (including THMs, haloacetaldehydes, haloacetonitriles, chloropicrin, cyanogen chloride, cyanogen bromide), 7 nitrosamines, as well as general water quality parameters, elemental analysis, free/total chlorine and bromide concentrations, were also collected. Questionnaires were used to collect information about the plant treatment processes. One or more of the iodo-THM congeners were detected in 15/16 WTPs investigated. Maximum total iodo-THM concentrations determined in the survey ranged from 0.11 µg/L to 26.82 µg/L. The maximum total iodo-THM concentrations were > 1 µg/L, in 8/16 WTPs and the highest maximum total iodo-THM concentration of >10 µg/L was seen in 4/16 WTPs. The total concentrations and the speciation of iodo-THMs were strongly influenced by the presence of ammonium in the source water and by the treatment regime (e.g., free chlorine residual). The bromide content of the source water did not have a significant influence on iodo-THM concentrations or speciation. The results of this study show that elevated sodium levels and the presence of naturally occurring ammonium in the source water are good markers for selecting WTP with the potential to form elevated levels of iodo-THMs in the treated water and thus, could provide the basis for future decisions regarding changing secondary disinfectant from chlorine to chloramine. This is important in Canada since WTPs using water sources with elevated salinity typically have difficulty maintaining the total THM levels to within the guideline level of 100 µg/L. These findings also support the need to monitor for naturally occurring ammonia, especially in high saline waters. Because iodo-THMs were found to occur in a large number of the systems investigated, more information about the toxicology of iodo-THMs would be important in assessing the potential risks for human exposure to iodo-THMs.

Nano-silver in drinking water and drinking water sources: stability and influences on disinfection by-product formation

Nano-silver is increasingly used in consumer products from washing machines and refrigerators to devices marketed for the disinfection of drinking water or recreational water. The nano-silver in these products may be released, ending up in surface water bodies which may be used as drinking water sources. Little information is available about the stability of the nano-silver in sources of drinking water, its fate during drinking water disinfection processes, and its interaction with disinfection agents and disinfection by-products (DBPs). This study aims to investigate the stability of nano-silver in drinking water sources and in the finished drinking water when chlorine and chloramines are used for disinfection and to observe changes in the composition of DBPs formed when nano-silver is present in the source water. A dispersion of nano-silver particles (10 nm; PVP-coated) was used to spike untreated Ottawa River water, treated Ottawa River water, organic-free water, and a groundwater at concentrations of 5 mg/L. The diluted dispersions were kept under stirred and non-stirred conditions for up to 9 months and analyzed weekly using UV absorption to assess the stability of the nano-silver particles. In a separate experiment, Ottawa River water containing nano-silver particles (at 0.1 and 1 mg/L concentration, respectively) was disinfected by adding sodium hypochlorite (a chlorinating agent) in sufficient amounts to maintain a free chlorine residual of approximately 0.4 mg/L after 24 h. The disinfected drinking water was then quenched with ascorbic acid and analyzed for 34 neutral DBPs (trihalomethanes, haloacetonitriles, haloacetaldehydes, 1,1 dichloro-2-propanone, 1,1,1 trichloro-2-propanone, chloropicrin, and cyanogen chloride). The results were compared to the profile of DBPs obtained under the same conditions in the absence of nano-silver and in the presence of an equivalent concentration of Ag(+) ions (as AgNO3). The stability of the nano-silver dispersions in untreated Ottawa River water, with a dissolved organic carbon concentration of 6 mg/L, was significantly higher than the stability of the nano-silver dispersions in distilled, organic-free water. Nano-silver particles suspended in the groundwater agglomerated and were quickly and quantitatively removed from the solution. Our data confirm previous observations that natural dissolved organic matter stabilizes nano-silver particles, while the high-ionic strength of groundwater appears to favor their agglomeration and precipitation. As expected, nano-silver was not stable in Ottawa River water through the chlorination process, but survived for many days when added to the Ottawa River water after treatment with chlorine or chloramines. Stirring appeared to have minimal effect on nano-silver stability in untreated and treated Ottawa River water. The profile of DBPs formed in the presence of nAg differed significantly from the profile of DBPs formed in the absence of nAg only at the 1 mg/L nAg concentration. The differences observed consisted mainly in reduced formation of some brominated DBPs and a small increase in the formation of cyanogen chloride. The reduced formation of brominated congeners may be explained by the decrease in available bromide due to the presence of Ag(+) ions. It should be noted that a concentration of 1 mg/L is significantly higher than nAg concentrations that would be expected to be present in surface waters, but these results could be significant for the disinfection of some wastewaters with comparably high nano-silver concentrations.

Insular ischemic stroke: clinical presentation and outcome

Background

The insula is a small but complex structure located in the depth of the sylvian fissure, covered by the frontal, parietal and temporal operculum. Ischemic strokes limited to the insula are rare and have not been well studied. Our objective is to better define the clinical presentation and outcome of insular ischemic strokes (IIS).

Methods

We reviewed the institutional prospective, consecutive stroke database from two centers to identify patients with IIS seen between 2008 and 2010. We also searched the Medline database using the keywords insula(r), infarction and stroke to identify previously published IIS cases confirmed by MRI. Minimal extension to an adjacent operculum or subinsular area was accepted. Clinicoradiological correlation was performed by distinguishing IIS involving the anterior (AIC) or posterior insular cortex (PIC). We collected clinical, demographic and radiological data. The outcome was determined using the modified Rankin Scale (mRS).

Results

We identified 7 patients from our institutions and 16 previously published cases of IIS. Infarcts were limited to the AIC (n = 4) or the PIC (n = 12) or affected both (n = 7). The five most frequent symptoms were somatosensory deficits (n = 10), aphasia (n = 10), dysarthria (n = 10), a vestibular-like syndrome (n = 8) and motor deficits (n = 6). A significant correlation was found between involvement of the PIC and somatosensory manifestations (p = 0.04). No other statistically significant associations were found. IIS presentation resembled a partial anterior circulation infarct (n = 9), a lacunar infarct (n = 2) or a posterior circulation infarct (n = 2). However, most cases presented findings that did not fit with these classical patterns (n = 10). At the 6 month follow up, mRS was 0 in 8/23 (35%) patients, 1–2 in 7/23 (30%) and unknown in 8/23 (35%).

Conclusions

IIS presentation is variable. Due to the confluence of functions in a restricted region, it results in multimodal deficits. It should be suspected when vestibular-like or motor but especially somatosensory, speech or language disturbances are combined in the same patient. The outcome of IIS is often favorable. Larger prospective studies are needed to better define the clinical presentation and outcome of IIS.

Randomized controlled trial of prevention of perineal trauma by perineal massage during pregnancy

OBJECTIVE

The aim of the study was to evaluate the effectiveness of perineal massage during pregnancy for the prevention of perineal trauma at birth.

STUDY DESIGN

Pregnant women with (n = 493) and without (n = 1034) a previous vaginal birth from 5 hospitals in the province of Québec, Canada, participated in this single-blind, randomized, controlled trial. All participants received oral and written information on the prevention of perineal trauma. Women in the experimental groups were requested to perform a 10-minute perineal massage daily from the 34th or 35th week of pregnancy until delivery.

RESULTS

Among participants without a previous vaginal birth, 24.3% (100/411) from the perineal massage group and 15.1% (63/417) from the control group were delivered vaginally with an intact perineum, for a 9.2% absolute difference (95% confidence interval 3.8%-14.6%). The incidence of delivery with an intact perineum increased with compliance with regular practice of perineal massage (chi2 for trend 13.2, P = 0.0003). Among women with a previous vaginal birth, 34.9% (82/235) and 32.4% (78/241) in the massage and control groups, respectively, were delivered with an intact perineum, for an absolute difference of 2.5% (95% confidence interval -6.0% to 11.0%). There were no differences between the groups in the frequency of sutured vulvar and vaginal tears, women's sense of control, and satisfaction with the delivery experience.

CONCLUSION

Perineal massage is an effective approach to increasing the chance of delivery with an intact perineum for women with a first vaginal delivery but not for women with a previous vaginal birth.

[Hypertrichosis and gingival hypertrophy regression in renal transplants following the substitution of cyclosporin by tacrolimus]

Gingival Hyperplasia (GH) and hypertrichosis (HT) are two sides effects associated with the usage of cyclosporine (CyA) but not with tacrolimus (FK 506). The aim of this study is to evaluate the efficacy and security of the conversion from CsA to FK 506 to treat those two complications. From August 1996 to May 1997, 15 patients (9 males, 6 females) aged from 23 to 63 years old (38 +/- 14, mean +/- SD) were switched from CsA to FK 506, 12 for GH, 2 for HT and one for combined presentation. FK 506 was first initiated at a dose of 0.15 mg/kg/day and then adjusted to a level target of 8 ng/ml. The conversion was done on an out patient basis at average 35 (5-83) months after transplantation. Patients were followed prospectively for 12 months. There was a significant reduction in GH in all patients within 3 months. Five out 13 patients had a complete resolution of GH within three months of conversion, 9/12 within 6 months and all by 12 months. HT resolved completely within 6 months. No rejection episode occurred and the serum creatinin remain stable over one year post conversion. Conversion from CsA to FK 506 is thus a safe and valid option to treat CsA induced GH and HT.