An Assessment of Current and Past Concentrations of Trihalomethanes in Drinking Water throughout France.

In France, 95% of people are supplied with chlorinated tap water. Due to the presence of natural organic matter that reacts with chlorine, the concentrations of chlorination by-products (CBPs) are much higher in chlorinated water produced from surface water than from groundwater. Surface water supplies 33% of the French population. Until the 1980s, almost all surface water utilities pre-chlorinated water at the intake. Pre-chlorination was then gradually banned from 1980 to 2000. Trihalomethanes (THMs) are the only regulated CBP in France. Since 2003, THMs have been monitored at the outlet of all utilities. This study assessed current (2005⁻2011) and past (1960⁻2000) exposure of the French population to THMs. We developed an original method to model THM concentrations between 1960 and 2000 according to current concentrations of THMs, concentration of total organic carbon in raw and finished water, and the evolution of water treatments from 1960 onward. Current and past mean exposure of the French population to THMs was estimated at 11.7 µg·L-1 and 17.3 µg·L-1, respectively. In the past, approximately 10% of the French population was exposed to concentrations >50 µg·L-1 vs. 1% currently. Large variations in exposure were observed among France's 100 administrative districts, mainly depending on the water origin (i.e., surface vs. ground), ranging between 0.2 and 122.1 µg·L-1 versus between 1.8 and 38.6 µg·L-1 currently.

Variations in trihalomethane levels in three French water distribution systems and the development of a predictive model.

Epidemiological studies have demonstrated that chlorination by-products in drinking water may cause some types of cancer in humans. However, due to differences in methodology between the various studies, it is not possible to establish a dose-response relationship. This shortcoming is due primarily to uncertainties about how exposure is measured-made difficult by the great number of compounds present-the exposure routes involved and the variation in concentrations in water distribution systems. This is especially true for trihalomethanes for which concentrations can double between the water treatment plant and the consumer tap. The aim of this study is to describe the behaviour of trihalomethanes in three French water distribution systems and develop a mathematical model to predict concentrations in the water distribution system using data collected from treated water at the plant (i.e. the entrance of the distribution system). In 2006 and 2007, samples were taken successively from treated water at the plant and at several points in the water distribution system in three French cities. In addition to the concentrations of the four trihalomethanes (chloroform, dichlorobromomethane, chlorodibromomethane, bromoform), many other parameters involved in their formation that affect their concentration were also measured. The average trihalomethane concentration in the three water distribution systems ranged from 21.6 µg/L to 59.9 µg/L. The increase in trihalomethanes between the treated water at the plant and a given point in the water distribution system varied by a factor of 1.1-5.7 over all of the samples. A log-log linear regression model was constructed to predict THM concentrations in the water distribution system. The five variables used were trihalomethane concentration and free residual chlorine for treated water at the plant, two variables that characterize the reactivity of organic matter (specific UV absorbance (SUVA), an indicator developed for the free chlorine consumption in the treatment plant before distribution δ) and water residence time in the distribution system. French regulations impose a minimum trihalomethane level for drinking water and most tests are performed on treated water at the plant. Applied in this context, the model developed here helps better to understand trihalomethane exposure in the French population, particularly useful for epidemiological studies.

Natural and technical factors in faecal contamination incidents of drinking water in small distribution networks, France, 2003-2004: a geographical study.

This geographical study aimed to show natural or water-processing-related factors of faecal contamination incidents (FCIs) of drinking water in continental France. We defined a FCI as the occurrence of at least 20 colony-forming Escherichia coli or enterococci among all the 100 mL samples collected for regulatory purpose within one day from a given drinking water supply zone (SZ). We explored correlations between the standardized number of FCIs per département (N_Pols) and various indicators related to weather, land cover, topography, geology and water management for three SZ size sub-classes. In 2003-2004, 2,739 FCIs occurred in SZs supplying fewer than 2,000 people, mainly with simply disinfected groundwater. N_Pols correlates with four covariates: (1) precipitation; (2) the extension of the karst outcrops; (3) the extent of disinfection; and (4) catchment protection. One hundred millimetres of yearly excess in precipitation increases the pollution risk by 28-37%, depending on the sub-class. A 10% extension of the karst areas, a 10% increase of unprotected resources, or of SZs with no disinfection, could entail a higher risk of FCI by about 10%. The correlations are reproducible over the three sub-classes and corroborate expert appraisals. These results encourage the ongoing effort to generalize disinfection and catchment protection.

Ms identification of microcystin-LR chlorination by-products.

Drinking water disinfection by chlorine is known to reduce concentration of microcystin, but compounds formed are rarely considered. In this work the chlorination of microcystin-LR has been studied by monitoring reactants consumption and reaction products using the linear trap quad-Orbitrap (LTQ-Orbitrap) technology. Microcystin-LR was totally transformed within 2 min, meanwhile chlorine was consumed until 30 min with a rate of 12 mol per mol of toxin. Four new by-products of microcystin-LR were identified as well as their isomers: monochloro-microcystin, monochloro-dihydroxy-microcystin, dichloro-dihydroxy-microcystin and trichloro-hydroxy-microcystin. In addition, four new isomers were also observed, corresponding to the dihydroxy-microcystin already known. Besides, another compound previously observed was identified as monochloro-hydroxy-microcystin.

Field experiments for the evaluation of pesticide spray-drift on arable crops.

Two distinct approaches were used to characterise spray-drift during the application of atrazine and alachlor to a maize crop. The first consisted in determining the quantities which did not reach their target. A first experiment was carried in 2001 to improve the sampling method. A second experiment in 2002 showed that losses represented 46 and 38% for atrazine and alachlor, respectively. The second approach was to follow the spatiotemporal evolution of the cloud formed during application. The concentrations observed near the application zone during spraying reached 4.5 microg m(-3) for atrazine and 8.5 microg m(-3) for alachlor. With alachlor these concentrations decreased rapidly when increasing distance from the plot or time following treatment, whereas in the case of atrazine they stabilised rapidly (between 0.5 and 0.3 microg m(-3)) both in space and in time. Deposits around the plot were light and slightly higher for alachlor (from 20 to 130 microg m(-2)). Alachlor was more rapidly diluted in space than atrazine, reflecting a differentiated evolution of physical form during the process. Alachlor, being more volatile than atrazine, is quickly transferred to the gaseous phase which was more rapidly dispersed than aerosols.

Assessing the transfer of pesticides to the atmosphere during and after application. Development of a multiresidue method using adsorption on Tenax and thermal desorption-GC/MS.

An air sampling and analytical method based on adsorption on porous polymer (Tenax TA) followed by automatic thermal desorption (ATD) and GC/MS analysis was developed for ten pesticides commonly used on major crops in Britanny and some of their metabolites in air (from spray drift and volatilisation transfer processes): alachlor, atrazine (and two major degradation products: deethylatrazine and deisopropylatrazine), carbofuran, cyprodinil, epoxyconazole, iprodione (and 3,5-dichloroaniline), lindane (and -HCH, its isomer), metolachlor, terbuconazole and trifluralin. This method was established with special consideration for optimal thermal desorption conditions, linear ranges, limits of detection and quantification. Moreover, collection efficiencies of Tenax TA at room temperature were examined. This method was then applied to the determination of ambient pesticide levels during the spraying season at a rural area. The method was also applied to determine the vertical gradient of alachlor concentrations on a treated maize parcel to evaluate volatilisation fluxes.

Comparison of different sampling techniques for the evaluation of pesticide spray drift in apple orchards.

An analytical method using gas chromatography-mass spectrometry has been developed for the evaluation of different sampling techniques to characterise spray drift in a commercial apple orchard. Eleven pesticides were studied (fungicides, insecticides and herbicides). A collection of airborne spray-drift pesticides released from a low-profile air-blast orchard sprayer was investigated using six types of samplers: (1) a Perkin-Elmer low volume automatic air sampler using with glass tube packed with Supelpak-2; (2) a high volume air sampler: (3, 4) an impinger containing cyclohexane that could be preceded by a glass fibre filter; and (5, 6) glass cartridges packed with Supelpak-2 that could be preceded by a glass fibre filter. Retention efficiencies of the different sampling techniques are compared, and physical forms of the retained pesticides are discussed. These techniques have allowed us to evaluate pesticide spray-drift in the orchard. Results have shown that the molecules' properties (k(H) and vapour pressure) and weather conditions (temperature and relative humidity) strongly influence pesticide gas and particles distribution. However, in the studied orchard, it is difficult to differentiate pesticide spray-drift and post-application transfers since treatment duration was > 2 days.