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PubMedDate not supplied

Effect of saliva contamination on the microshear bond strength of one-step self-etching adhesive systems to dentin.

This study evaluated the effect of saliva contamination and decontamination methods on the dentin bond strength of one-step self-etching adhesive systems. Three commercially available "all-in-one" adhesives (One Up Bond F, Xeno III and Adper Prompt) and one resin composite (Filtek Z-250) were used. Third molars stored in distilled water with 0.5% thymol at 4 degrees C were ground with #600 SiC paper under running water to produce a standardized smear layer. The specimens were randomly divided into groups according to contamination methods: no contamination, which was the control (C); contamination of the adhesive surface with fresh saliva before light curing (A) and contamination of the adhesive surface with fresh saliva after light curing (B). Each contamination group was further subdivided into three subgroups according to the decontamination method: A1-Saliva was removed by a gentle air blast and the adhesive was light-cured; A2-Saliva was rinsed for 10 seconds, gently air-dried and the was adhesive light-cured; A3-Saliva was rinsed and dried as in A2, then the adhesive was re-applied to the dentin surface and light-cured; B1-Saliva was removed with a gentle air blast; B2-Saliva was rinsed and dried; B3-Saliva was rinsed, dried and the adhesive was re-applied and light cured. Tygon tubes filled with resin composite were placed on each surface and light cured. All specimens were stored in distilled water at 37 degrees C for 24 hours. Microshear bond strength was measured using a universal testing machine (EZ test), and data were analyzed by one-way ANOVA followed by the Duncan test to make comparisons among the groups (p<0.05). After debonding, five specimens were selected and examined in a scanning electron microscope to evaluate the modes of fracture. The A2 subgroup resulted in the lowest bond strength. For One Up Bond F and Adper Prompt, there was no significant difference between subgroup A1 and the control, and subgroup A3 and the control (p>0.05). Bond strengths of all B groups were significantly lower compared to the controls (p<0.05). For Xeno III, A1 subgroup showed the greatest decrease in bond strength as compared to the control (p<0.05). On the other hand, it showed more resistance to salivary contamination after adhesive curing. There was no statistically significant difference among the control groups (p>0.05).

Air↗

PubMed1981

Influence of 90Sr-contaminated milk on the ovaries of foetal and young mice.

A dose of 185 kBq (5 microCi) 90Sr was intravenously injected into pregnant CBA-mice on the 19th day post coitum. Four groups of female young were examined when aged 56 days: (1) non-contaminated females (controls), (2) only exposed in utero, (3) only having suckled contaminated milk and (4) exposed to 90Sr in utero and having suckled contaminated milk. The effect of the nuclide was expressed as a comparison of the number of remaining cells in the ovaries, totally and in different stages of development, between 90Sr-contaminated young and controls. Young mice that suckled contaminated milk had a reduced number of cells compared with the controls. The ovaries of in utero contaminated females were injured to a less severe degree if the individuals were given noncontaminated milk, compared with those suckling contaminated dams. Minute changes of the body burden of 90Sr were especially reflected in the number of young oocytes, being the most radiation sensitive stage during the ovarian development.

Animals↗

PubMed1995

Evaluation of the chicken crop as a source of Salmonella contamination for broiler carcasses.

Much previously published research has focused on the role of cecal and intestinal Salmonella contamination of poultry carcasses within commercial processing plants. Presently, we have evaluated the persistence of experimentally inoculated Salmonella enteritidis in the crops and ceca of commercial broiler chickens during the last week of growth (Weeks 6 to 7) and the presence of crop and cecal Salmonella in 7-wk-old broilers in a commercial processing plant. When broilers were inoculated with 1 x 10(6) cfu S. enteritidis at 6 wk of age by oral gavage, the incidence of crop and cecal contamination was equivalent 2d after challenge (30%), with only 1 of 29 crops contaminated and 0 of 29 ceca contaminated at 7 d following challenge. When broilers were inoculated with 1 x 10(8) cfu S. enteritidis at 6 wk of age by oral gavage, 2 d after challenge the crops and ceca were observed to be 57 and 67% positive for S. enteritidis, respectively. Seven days after inoculation with 1 x 10(8) S. enteritidis, the crops and ceca were 37 and 57% positive, respectively, for the challenge organism. At a commercial broiler processing plant, 286 of 550 crops from three flocks were Salmonella-positive, whereas only 73 of 500 ceca from these flocks were contaminated. Furthermore, data from this plant indicated that the crops were far more likely to rupture than ceca (86-fold) during processing, increasing the possibility of carcass contamination with Salmonella derived from crop contents. The results of these studies suggest that the crop may serve as a source of carcass contamination with Salmonella within some processing plants.

Animals↗

PubMed1998

The contamination of pâté with Listeria monocytogenes--results from the 1994 European Community-Coordinated Food Control Program for England and Wales.

The Listeria monocytogenes contamination of 3,065 pâté products sampled at the point of retail sale in England and Wales was examined. Ninety-seven percent of samples were free of contamination with L. monocytogenes, 2.0% (60) had levels of less than 200 CFU/g, and 0.6% (18) had levels of 200 CFU/g or more. Fish and seafood pâté were significantly more commonly contaminated by L. monocytogenes than other pâté types (chi 2 test, P = 0.001). Pâté obtained from small retail shops was significantly more likely to be contaminated at levels of > or = 200 CFU/g (chi 2 tests, P < 0.0005) than that obtained from supermarkets. L. monocytogenes was isolated significantly more often (chi 2 tests, P < 0.00002) from packs of pâté that were open at the time of collection (3.8%) than those that were sold prepacked (1.2%). There were also significantly more samples (chi 2 test, P = 0.0009) where L. monocytogenes was recovered at higher levels (> or = 200 CFU/g) in opened, as compared to prepacked, samples. There was a significant difference in the rates and levels of contamination of opened samples between shops and supermarkets (chi 2 tests, P < 0.0025). Evidence from this study shows that most of the pâté sold in England and Wales is not contaminated with L. monocytogenes, and we suggest that the main areas of concern are cross-contamination and the length of display of pâté sold from opened packs.

Animals↗

PubMed1999

[Investigation of radiation safety management of nuclear medicine facilities in Japan; contamination of radioactivity in the draining-water system. A Working Group of Japanese Society of Nuclear Medicine for the Guidelines of Nuclear Medicine Therapy].

Radiation safety management condition in Japanese nuclear medicine facilities were investigated by the questionnaire method. The first questionnaire was asked in all Japanese 1,401 Nuclear Medicine facilities. Answers from 624 institutes (44.5%) were received and analyzed. The radiation-safety management in nuclear medicine institutes was considered to be very well performed everyday. Opinion for the present legal control of nuclear medicine institutes was that the regulation in Japan was too strict for the clinical use of radionuclides. The current regulation is based on the assumption that 1% of all radioactivity used in nuclear medicine institutes contaminates into the draining-water system. The second questionnaire detailing the contamination of radioactivity in the draining-water system was sent to 128 institutes, and 64 answers were received. Of them, 42 institutes were considered to be enough to evaluate the contamination of radioactivity in the draining-water system. There was no difference between 624 institutes answered to the first questionnaire and 42 institutes, where the radioactivity in the draining-water system was measured, in the distribution of the institute size, draining-water system equipment and the radioactivity measuring method, and these 42 institutes seemed to be representative of Japanese nuclear medicine institutes. Contamination rate of radioactivity into the draining system was calculated by the value of radioactivity in the collecting tank divided by the amount of radionuclides used daily in each institute. The institutes were divided into two categories on the basis of nuclear medicine practice pattern; type A: in-vivo use only and type B: both in-vivo and in-vitro use. The contamination rate in 27 type A institutes did not exceed 0.01%, whereas in 15 type B institutes the contamination rate distributed widely from undetectable to above 1%. These results indicated that the present regulation for the draining-water system, which assumed that 1% of all radioactivity used in nuclear medicine institutes contaminated into draining-water system, should be reconsidered in nuclear medicine facilities where radionuclides are used only in in-vivo studies.

Health Facilities↗

PubMed2000

[Magnitude of rainfall on viral contamination of the marine environment during gastroenteritis epidemics in human coastal population].

BACKGROUND: Sewage treatments are not efficient to eliminate enteric microorganisms. Viruses are able to persist and are discharged into the marine environment with treated effluents. Few data are now available on the magnitude and the contributive processes of marine viral contamination. This work evaluates the relationship between the magnitude of rainfall and the viral contamination of the marine environment during winter epidemics of gastroenteritis in human coastal populations. METHODS: A RT-PCR method was used to detect enterovirus, hepatitis A virus, Norwalk-like virus, astrovirus and rotavirus in shellfish, harvested monthly between August 1995 and July 1998. The frequency of virus detection in shellfish was expressed as an Index of Viral Contamination. Acute gastroenteritis in the population was estimated using the French Sentinel System for Monitoring of Communicable Diseases. Rainfall effects on the efficiency of sewage treatment were assessed using an estimated staying time of sewage effluents in the plant. RESULTS: The results indicate that the highest viral contamination occurs in winter. Maximal indexes of viral contamination were respectively 70% in January 1996, 100% in January 1997, but only 31% in January 1998. Viral contamination variations seemed to follow the pattern of the winter epidemic of acute gastroenteritis in the local population in 1996 and 1997. These observations should be linked to the winter rainfalls. Heavy rains on short periods of time could create an hydraulic overload in the sewage treatment plant, reducing the staying time of the sewage effluents and thus the efficiency of the disinfection process. CONCLUSION: The magnitude of the viral contamination of shellfish seems to result from the simultaneity between the winter epidemics of acute gastroenteritis in the coastal population and heavy rainfall. To prevent public health hazards associated with shellfish consumption, the monitoring of microbiological quality in shellfish harvesting areas should include accompagning survey of viral epidemic in the coastal population, and of sewage outputs in the coastal environment.

Disease Outbreaks↗

PubMed2000

[Effect of mycoplasma contamination of a human cervical carcinoma cell line M HeLa clone 11 on karyotypic variability].

The karyotypic variability has been investigated for an immortalized human epithelioid cervix carcinoma cell line M HeLa clone 11, cultivated for 15-60 days after contamination with Acholeplasma laidlawii A, strain PG-8, and for 30 days after contamination with Mycoplasma arginini R-16. The character of cell distribution for chromosome number changes in contaminated cells significantly, as compared to the control. So, the frequency of cells with the modal number of chromosomes being equal to 50 decreases significantly, and the range of variability in the number of chromosomes increases. With the prolongation of the term of cultivation in control variants up to 60 days the character of cell distribution for chromosomal number changes, as compared to the preceding terms (15 and 30 days), which is expressed in the extended range of variability in the chromosomal number at the expense of decreased frequency of cells with submodal number of chromosomes equal to 49. But the degree of these changes is significantly smaller than in contaminated variants. The frequency of polyploid cells did not differ in all investigated variants. The number of chromosomal aberrations in cultures contaminated with A. laidlawii (for 15-60 days) and M. arginini (for 30 days) does not differ from that in the corresponding controls. The absence of dicentrics (telomeric association) at a long-term contamination of the human epithelioid cervix carcinoma cell line M HeLa clone 11 having marker chromosomes in karyotype and a comparison of these results with the earlier obtained data on other "marker" and "markerless" cell lines seems to confirm the point of view that dicentrics appear a characteristic feature of karyotypic variability of "markerless" cell lines, mainly with a long-term contamination in different conditions.

HeLa Cells↗

PubMed2001

Bioavailability of lab-contaminated and native polycyclic aromatic hydrocarbons to the amphipod Corophium volutator relates to chemical desorption.

In the present study, the relationship between bioavailability of polycyclic aromatic hydrocarbons (PAHs) to benthic amphipods and the PAH desorption kinetics was examined. To that end, field-contaminated sediment was treated in three different ways. One subsample had no addition of PAHs and contained native PAHs only. To a second subsample, six PAHs (phenanthrene, fluoranthene, anthracene, pyrene, benzo[b]fluoranthene, and benzo[k]fluoranthene) were added in the laboratory. Two of the PAHs were added at higher concentrations to a third subsample, serving as a control for concentration-dependent uptake. Marine amphipods (Corophium volutator) were exposed to the three subsamples for a maximum of 25 d and were subsequently analyzed. Desorption kinetics were determined for both the lab-contaminated and the native PAHs. The biota-to-sediment accumulation factor (BSAF) values of the individual native and lab-contaminated PAHs correlated well with the rapidly desorbing fraction (R2 = 0.76). The BSAFs were 1.4 to 3.3 higher for the lab-contaminated PAHs compared with the native PAHs, while the difference between the rapidly desorbing fractions was a factor of 1.1 to 1.8. The BSAFs of the lab-contaminated PAHs in the second and third subsample were equal, indicating concentration-independent accumulation. The results suggest that lab-contaminated PAHs are more available to amphipods than native PAHs and that differences in bioavailability of lab-contaminated and native PAHs to marine amphipods are related to differences in desorption behavior.

Animals↗

PubMed1998

Microbial contamination of advanced life support (ALS) systems poses a moderate threat to the long-term stability of space-based bioregenerative systems.

Microbial contamination of terrestrial hydroponic plant-growing systems provides an effective analogue for studying microbial contamination issues for space-based advanced life support (ALS) systems. If aggressive root or foliar pathogens are introduced into ALS hydroponic systems, severe epidemics are probable. Greater than 80% of the reported outbreaks of root pathogens in terrestrial hydroponic systems describe epidemics caused by fungal species of Fusarium, Phytophthora, and Pythium. However, it is likely that a comprehensive sanitation and quarantine program for space-based ALS modules will prevent contamination by Phytophthora and Pythium spp. because these pathogens are general soilborne. However, Fusarium spp. are typically airborne, can grow saprophytically on diverse substrates, and have been common contaminants of American spacecraft. If comprehensive sanitation and quarantine programs are established for space-based ALS modules, then the threat of pathogen introductions into these systems will be significantly mitigated. Microbial contamination studies in spacecraft over the last 30 years indicate that a high diversity of bacteria, fungi, and actinomycetes are commonly carried on board probably via clothing, equipment, air currents during spacecraft handling and loading, food, and the astronauts themselves. Species of Alternaria, Aspergillus, Botrytis, Candida, Cephalosporium, Cladosporium, Fusarium, Mucor, Penicillium, Phoma, and Trichoderma were the most prevalent fungi recovered, and species of Bacillus, Escherichia, Klebsiella, Micrococcus, Pseudomonas, Staphylococcus, and Streptococcus were the most prevalent bacteria recovered from spacecraft. Most of these genera contain species that have been reported as plant pathogens. Strict quarantine procedures were not effective in preventing contamination of spacecraft during these missions. Research must be initiated to better understand how microorganisms interact with plants and animals in microgravity environments because microbial contamination of spacecraft and ALS modules cannot be avoided. An integrated pest management (IPM) program likely will be developed for managing plant disease outbreaks in space-based ALS systems.

Ecological Systems, Closed↗

PubMed2002

Genetic effects of mercury contamination on aquatic snail populations: allozyme genotypes and DNA strand breakage.

Allozyme data and DNA strand break frequencies were compared among populations of Pleurocera canaliculatum from five sites with varying mercury contamination on the North Fork Holston River (NFHR) in southwestern Virginia, USA. Allozyme genotype frequencies for four loci were significantly different between populations from the three most highly contaminated sites and those from two lesser contaminated sites. In addition, heterozygosity at three of these loci was significantly lower in the populations from the most highly contaminated sites. The DNA strand break frequency was significantly correlated to whole-body total mercury concentration in snails from three sites. These data add to the evidence supporting the use of DNA strand breakage as an indicator of chemical contamination and the use of allozyme analysis as a marker of contamination and possible selection for pollution resistance. However, the relationship between contaminant-induced changes in the genetic variation of enzymes of central metabolism and the functionalities upon which selection for resistance may act remain unclear, and mechanisms other than selection for resistance must be considered. Use of enzymes from other biochemical pathways may be appropriate for other species or for those under other chemical pollution pressures.

Adaptation, Physiological↗

PubMed1992

[Levels of mercury in samples of bees and honey from areas with and without industrial contamination].

Increasing numbers of specialists have been concerned with the problem of friendly environment in relation to man as well as to farm and wild animals. Greater interest in the biological monitoring of environment and ecosystem contamination can be observed. Determination of residues of organic and inorganic substances in bees (Apis mellifera) and in their products is one of effective possibilities of environmental pollution monitoring. Our work was aimed at the study of mercury levels in bees and their products. Mercury levels were determined in the head, abdomen and thorax of bees (Apis mellifera) from 20 bee populations coming from industrially contaminated areas with a dominant load of mercury (10 populations) and from uncontaminated areas. Mercury levels were determined simultaneously in honey coming from both contaminated and uncontaminated areas. The following mercury levels were found in bees from the contaminated area: heads 0.029-0.385 mg/kg, thorax 0.028-0.595 mg/kg and abdomen 0.083-2.255 mg/kg. Mercury levels in samples from uncontaminated areas ranged from 0.004 to 0.024 mg/kg in the heads, from 0.004 to 0.008 mg/kg in the thorax and from 0.008 to 0.020 mg/kg in the abdomen. In honey samples from the contaminated and uncontaminated areas mercury levels ranged from 0.050 to 0.212 mg/kg and from 0.001 to 0.003 mg/kg, respectively. The results of sample analyses for mercury loads in bees and honey from both contaminated and uncontaminated areas are given in Tab. I. Mean mercury levels in the single parts of the body in Apis mellifera and in honey from contaminated and uncontaminated areas are given in Figs. 1, 2, 3.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMedDate not supplied

[The surveillance of the aeraulic and hydraulic system reduce environmental Aspergillus contamination in hospital].

The aim of this work was to value the evolution of environmental Aspergillus contamination in hospital with respect to aeraulic system and bathrooms works. An analysis on levels of air and surface Aspergillus contamination were determined in patient's rooms and various common sites in a ward of an hospital in Genoa in 1999. As high contamination levels were found, in summer 1999 a radical disinfection and revision of the aeraulic system was settled. In spite of these interventions some samples maintained an high contamination level, even if from only two rooms, so a further disinfection of bathrooms and surfaces became necessary. A period of sampling was conducted after this last intervention until November 2002. At the beginning of our surveillance 59% positive samples and about 50% of them with high contamination level (>1000 CFU/m3) were found. After the revision of the aeraulic system the reduction of positive samples was significative (14.2%), besides all the positive samples regarded only two rooms. In the last valuation period, after a further disinfection of bathrooms and surfaces of the above mentioned rooms, all the samples taken resulted with a contamination level lower than 10 CFU/m3. This findings underlines the importance of environmental surveillance looking for all the contaminated sources; in particular the aeraulic and hydraulic system as well as the proximity hospital building yard not sufficiently protected.

Air Conditioning↗

PubMed2004

[Simulation of biodegradation of petroleum contaminants in natural waters of the Yellow River].

Petroleum contaminants is one of the major pollutants in the Yellow River. Laboratory simulation experiments were carried out to study the natural biodegradation of the petroleum contaminants. When adding 10 mg/L petroleum contaminants to the Yellow River water samples containing 0 or 0.5 g/L sediment, the petroleum contaminants-degrading bacteria increased gradually after about one week of acclimatization. With the sediment content of 0.5 g/L, about 85% petroleum contaminants with the initial concentration of 11.64 mg/L in river water could be degraded within 63 days at 20 degrees C. The biodegradation rate was greatly influenced by the sediment content and the initial concentration of petroleum contaminants, and such effect was different from one degradation stage to another. In addition, the existence of sediment affected the biodegradation kinetics of petroleum contaminants.

Biodegradation, Environmental↗

PubMed1992

[Signal contamination problem in three-dimensional localization technique of MR spectroscopy--experiment and an analysis of patient data].

Signal contamination from the surrounding volume was studied using the ISIS sequence, a three-dimensional localization technique. In phantom experiments, contamination decreased with the increase of Tr, regardless of where the contamination originated from. In 52 localized liver spectra with a Tr of 2 sec, PCr contamination was estimated at 3 to 4%, and contamination of ATP signals from the surrounding liver tissue at less than 1%, because of the relatively short T1 of ATP in the liver. In the spectra of brain neoplasms obtained using the simultaneous double-volume selection technique, the PCr ratio in the tumor relative to the control area was high in low grade astrocytoma (0.80, n =8) and low in others (0.45, n = 11). Considering contamination and spectral noise, a PCr ratio of less than 0.4 does not strongly suggest the existence of PCr in tumors. Among 25 cases whose therapeutic processes were monitored by MRS, signal disappearance was observed in two cases in the localized spectra after therapy. In both of them, tumor necrosis was proved pathologically and correlated well with spectroscopic findings. It was found that the ISIS technique suppressed signal contamination to the level of several percents, providing spectra of acceptable quality through localization.

Humans↗

PubMed2006

[An approach to the theoretical meaning of ecological remediation of contaminated soil].

The objectives of contaminated soil remediation are to transfer and transform the hazardous contaminants in soil, to eliminate and reduce their toxicity, and to restore or partly restore the ecological service function of soil. Since soil contamination is always a combined one, it is essential to use multiple methods to remediate contaminated soil. It is a tendency of soil remediation to use a uniform method, which aims to restore the ecological service function of soil by combining the restoration of internal function with external clean function. This paper discussed the concepts of ecological remediation of contaminated soil, and the ecological principles which should be obeyed in ecological remediation. Bioremediation is very important for ecological remediation, and the method organization should obey the principles of technique optimization. Remediation efficiency can be improved if self clean function of soil system is strengthened and activated, together witb external clean function. Ecological factor adjustment is essential for contaminated soil remediation, and also, a basic characteristic of ecological remediation and an important means for the enhancement of remediation efficiency. Ecological remediation should be harmonious, efficient, and stable. The final objective of ecological remediation is to restore the ecological service function of soil, in which, the evaluation of ecological remediation is the base. Ecological remediation theory shall play an important role in contaminated soil remediation.

Biodegradation, Environmental↗

PubMed2006

Effects of saliva contamination on dentin bond strength using all-in-one adhesives.

PURPOSE: To evaluate the effects of saliva contamination on microtensile bond strengths of all-in-one adhesives to dentin. MATERIALS AND METHODS: Flat superficial occlusal dentin surfaces of extracted human molars were used and randomly divided into 2 groups depending on two all-in-one adhesives: One-Up Bond F Plus (Tokuyama Dental) and Adper Prompt L-Pop (3M ESPE). For each adhesive, the teeth were allocated to 7 subgroups in which one group was bonded without contamination with saliva, serving as a control. The other groups, either before or after the polymerization of adhesives, were contaminated with saliva and dried; contaminated, dried, and adhesives re-applied; contaminated, rinsed, and the adhesives re-applied. Resin composite was then placed on the treated dentin surfaces. After 24 h storage in distilled water at 37 degrees C, the teeth were sectioned perpendicular to the adhesive interface in x and y directions, obtaining multiple beam-shaped specimens with a cross-sectional area of approximately 1.0 mm2. Specimens were stressed in tension at 1 mm/min until rupture of the bond. Data were analyzed using one-way ANOVA and the Games-Howell test. RESULTS: For both all-in-one adhesives, saliva-contaminated groups showed lower bond strengths than the controls. Re-application of the adhesives after drying or rinsing the saliva off restored the dentin bond strengths to the control levels. CONCLUSION: Saliva contamination reduced the dentin bond strengths of all-in-one adhesives. Supplementary application of the adhesive after cleaning the saliva from the dentin surface is an empirical recommendation for restoring bond strength.

Adhesives↗

PubMed2006

[Organic contaminants in the Jakusevec landfill and their impact on groundwater quality].

Landfilling is probably, the most popular disposal method for the management of domestic and industrial waste. Unfortunately, many landfills around the world do not include leachate collection systems and present a considerable risk to the underlying aquifers. There have been numerous reports on groundwater contamination in the vicinity of unprotected landfills, paying particular attention to specific organic contaminants. This problem is especially pronounced in landfills which, in addition to ordinary domestic refuse, contain waste of industrial origin. Jakusevec, the main landfill of the city of Zagreb, belongs to this category. The recently completed remediation programme for Jakusevec included comprehensive investigations with the aim to quantify various organic contaminants in solid waste and establish their possible infiltration into the underlying soils and groundwater. A detailed analyses using chromatographic and mass spectrometric techniques made it possible to identify a number of contaminants. According to their origin, the identified compound classes can be divided into the two main categories: markers of biological waste and its microbial transformation and markers of anthropogenic waste. Our investigations have shown that the composition of organic contaminants changes dramatically during the vertical transport from the solid waste through the unsaturated zone of soil to aquifer sediments, which involves both physicochemical and biotransformation processes. The vertical transport of polar organic contaminants was very efficient and led to a significant contamination of the aquifer in the vicinity of the landfill.

Croatia↗

PubMed1979

Herbicide contamination and decontamination of well waters in Ontario, Canada, 1969-78.

OVER THE 10-YEAR period 1969-78, the waters of 237 wells were analyzed because of contamination from herbicide spillage in or near the well, complaints of impaired water flavor, or injury to seedling plants moistened with the well water. Herbicides were identified in 159 wells: 98 had a single herbicide, 46 had two, 12 had three, one had four, and another had five separate herbicides contributing to the contamination. Wells were grouped according to the mode of entry of the contaminant. Entry occurred most commonly as an aerial spray fdrift or in runoff. Serious contaminations were caused by spillage of herbicide concentrates and spray solutions in or around the well. Twenty-four of the contaminated wells were further investigated to determine the persistence of the contaminant and how to remove it. Some wells were decontaminated adequately to allow reuse within nine weeks, others required three years, and yet others had to be abandoned. Particularly persistent contaminants were amitrole, dinoseb, and picloram.

Herbicides↗