Human disodium octaborate tetrahydrate exposure following carpet flea treatment is not associated with significant dermal absorption

Disodium octaborate tetrahydrate is used for indoor flea control on carpets and furniture. Disodium octaborate tetrahydrate was applied to a 100% nylon carpet as a solution using a powered rug brush at a rate of approximately 200 micrograms/cm2 carpet. Two randomly chosen groups of volunteers (18 females, 4 males) wore either bathing suits which provided 75% or more skin exposure or whole-body, cotton dosimeters consisting of socks, union suits, and gloves. The volunteers performed a 20-minute set of Jazzercise routines. The availability of boron was demonstrated by covering portions of the carpet with a cotton dosimeter and rolling it with a weighted roller. Additionally, disodium octaborate tetrahydrate was transferred to the whole-body dosimeter. Volunteers also collected 24-hour urine specimens prior to and following the exercise period. The specimens were analyzed for total boron by inductively coupled plasma emission spectroscopy. No evidence of contact transfer and dermal absorption was obtained. The mean daily boron levels (mg/g creatinine) were 1.17, 1.33, and 1.31 for the group with exposed skin and 1.26, 1.12, and 1.26 for those who wore dosimeters which prevented contact. Daily urine boron levels were not significantly different when compared using a two sample t-test assuming equal variances (P > 0.05). Direct dermal contact with disodium octaborate tetrahydrate-treated carpet at a nominal rate of 200 micrograms/cm2 did not produce any adverse effects or change urinary boron clearance.

Surface morphology changes in human enamel, dentin and cementum following bleaching: a scanning electron microscopy study

Extracted human premolars were cut, cleaned and divided into 6 experimental groups. Each group was treated with one of the following bleaching materials: 30% hydrogen peroxide, 10% carbamide peroxide, sodium perborate, Nu-Smile, Opalescence and DentlBright. Morphological changes in tooth surface occurred following treatment with most bleaching agents. Hydrogen peroxide and DentlBright were associated with surface changes in all dental tissues. Hydrogen peroxide, DentlBright, Nu-Smile and Opalescence were mainly associated with surface changes in the cementum, which exhibited more changes than the other tissues.

Euglena gracilis as a supplementary test organism for detecting biologically active compounds

The mutagenic activity of more than 120 antimicrobial agents and protective components was investigated. Only Kathon showed a consistent increase in revertant counts in the Ames test on Salmonella typhimurium. The hereditary bleaching test on Euglena gracilis used for detecting extranuclear mutations, showed positive results for Kathon, triethanolamine and diamine silver tetraborate.

Effect of bleaching agents on dentin permeability to Streptococcus faecalis

Bacterial contamination of dentin may be a contributing factor in the development of bleaching-associated root resorption. In this study, the effect of commonly used bleaching agents on the permeability of dentin tubules to Streptococcus faecalis was evaluated. Sixty extracted bovine incisors were horizontally sectioned apically to the cementoenamel junction. In each tooth, a standard cavity was prepared, the pulp tissue extirpated, and remnants of soft tissue and smear layer were removed. Following rinsing and repeated autoclave sterilization, the teeth were divided into four groups, each treated with one of the following materials: 30% hydrogen peroxide, sodium perborate mixed with 30% hydrogen peroxide, sodium perborate mixed with distilled water, and distilled water alone that served as control. The bleaching agents were sealed in the teeth and incubated at 37 degrees C for 7, 14, and 21 days. At each time interval the bleaching agents were removed and the teeth incubated at 37 degrees C in brain heart infusion infected with S. faecalis. Histological sections were prepared, and the maximal bacterial penetration for each group was measured using a computerized morphometric system. Statistical analysis of the results revealed that teeth treated with either 30% hydrogen peroxide alone or in combination with sodium perborate were significantly more permeable to S. faecalis than those treated with sodium perborate mixed with water (p < 0.0001). Sodium perborate mixed with water did not cause an increase in dentin permeability to S. faecalis and was similar to the water control. In conclusion, it seems that bleaching agents containing hydrogen peroxide in high concentrations may increase bacterial penetration through dentinal tubules.

Acute and chronic respiratory effects of sodium borate particulate exposures

This study examined work-related chronic abnormality in pulmonary function and work-related acute irritant symptoms associated with exposure to borate dust in mining and processing operations. Chronic effects were examined by pulmonary function at the beginning and end of a 7-year interval. Time-specific estimates of sodium borate particulate exposures were used to estimate cumulative exposure during the study interval. Change in pulmonary function over the 7 years was found unrelated to the estimate of cumulative exposure during that interval. Exposure-response associations also were examined with respect to short-term peak exposures and incidence of five symptoms of acute respiratory irritation. Hourly measures of health outcome and continuous measures of particulate exposure were made on each subject throughout the day. Whenever a subject reported one of the irritant symptoms, a symptom intensity score was also recorded along with the approximate time of onset. The findings indicated that exposure-response relationships were present for each of the specific symptoms at several symptom intensity levels. The associations were present when exposure was estimated by both day-long and short-term (15-min) time-weighted average exposures. Associations persisted after taking account of smoking, age, and the presence of a common cold. No significant difference in response rate was found between workers exposed to different types of sodium borate dusts.

Reproductive effects of inorganic borates on male employees: birth rate assessment

The purpose of this study was to investigate the potential for reproductive effects of inorganic borate compounds on male employees. The standardized birth ratio (SBR) methodology was used to assess fertility among male employees, using live births as the measured end point. The ratio of female to male births was also assessed. Data were collected via questionnaires and telephone follow-up interviews. Medical insurance records were assessed for nonresponders. Exposures were assessed using three semiquantitative categories. We found a statistically significant increase in fertility as measured by live births among the employees of the inorganic borate facility. There does not appear to be any decrease in fertility due to exposures either as analyzed by the borate exposure categories or over time, which is an indirect measure of exposures. We found a nonstatistically significant increase in the percentage of female offspring. This increase was due, not to a deficiency of male offspring, but rather to a marked increase in the numbers of female offspring. This increase in percentage female offspring does not appear to be related to exposures to inorganic borates. Based on the data, exposures to inorganic borates do not appear to adversely affect fertility in this population.

Reproductive effects of sodium borates on male employees: birth rate assessment

OBJECTIVES

The purpose of the study was to investigate potential reproductive effects of sodium borates on occupationally exposed male employees at a large mining and production facility in the Mojave Desert of California.

METHODS

The standardised birth ratio (SBR) was used to assess fertility of the male employees. Live births were the measured end point, and the rate of female to male offspring was also assessed. Data were collected through a questionnaire after a series of on site introductory and explanatory meetings with the employees. Initial non-responders were followed up by telephone. Medical insurance records were assessed for those who declined to participate.

RESULTS

The questionnaire was a good method of ascertainment for live births. There was no evidence of selection bias in the results. There was a highly significant excess of offspring fathered by the male employees. There was no evidence of a relation between exposure and this excess of offspring, nor were there any temporal differences during the period of observation (> 30 years). Also, there was an excess of the percentage of female offspring fathered by these male employees. This excess of female offspring was not significant. There was no evidence of an exposure relation to sodium borates with this excess of female offspring nor were there any temporal differences.

CONCLUSION

Under the conditions studied, there were no adverse reproductive effects of high borate doses as reported from oral ingestion studies in animals.

Intracoronal bleaching: concerns and considerations

The history of intracoronal bleaching and the development of the walking bleach technique are reviewed. External cervical resorption associated with intracoronal bleaching is a serious sequela that has been reported in the literature. One explanation given for this phenomenon is that it results from an inflammatory process initiated by the presence of bleaching agents in the attachment apparatus. The basis for this conclusion is discussed. A review of published case reports on external cervical resorption associated with intracoronal bleaching revealed that: 100 per cent of the affected teeth had no intermediate dental base placed, 84 per cent were treated with a thermocatalytic technique, 80 per cent were bleached after the root canal sealer was fully set and 72 per cent had a history of trauma before bleaching. Based on these observations, it should be possible to safely bleach teeth intracoronally provided specific concerns and considerations are taken into account. These are: 1) the use of heat should be avoided; 2) an intermediate dental base should be placed with due respect to the attachment level; and 3) a base should be selected with due respect to its effectiveness in sealing tooth structure.

Application of an event marker in the occupational epidemiologic study of acute irritant symptoms

Field studies of occupational exposure to airborne irritants have predominantly relied on symptom surveys of study participants. As part of a new approach to the study of acute irritant symptoms, subjects exposed to sodium borate dusts recorded their symptom responses at hourly interviews as well as instantaneously on an electronic device called an event marker. Overall, the unprompted marks indicated fewer irritant events than the interviews. Marks were more frequent in the presence of more than one type of symptom and also appeared to reflect more severe symptoms. A proportion of the marked events occurred in time intervals when no symptoms were recalled during the interview. The exposure-response relations were similar regardless of whether they were based on the interview reports or the electronically marked symptoms. The event marker provided a means to examine the time of onset of the acute symptom event. It also made it possible to examine directly the timing profiles of symptom response in relation to changes in exposure levels in a field setting. Despite some inconsistencies, the finding suggests that the event marker may provide an alternative to frequent interviews of exposed workers to obtain irritant symptom responses for exposure-response modeling.

Shear bond strength of composite resin to unbleached and bleached human dentine

The purpose of this study was to compare the shear bond strength of composite resin to unbleached and bleached human dentine when used in conjunction with new dentine bonding systems. One hundred extracted, caries free, permanent human molars were used in this study. An in vitro walking bleach model was developed to stimulate clinical conditions during bleaching. It was found that the mean shear bond strength of composite resin to bleached dentine attained was lower than that to unbleached dentine. The value of 6.7 MPa bond strength to bleached human dentine demonstrated by All-Bond dentine conditioner and adhesive (Technique 1B) was much higher than in previous reports.

Dose related acute irritant symptom responses to occupational exposure to sodium borate dusts

A repeated measurement design was employed in the study of acute symptoms of eye and respiratory tract irritation resulting from occupational exposure to sodium borate dusts. The symptom assessment of the 79 exposed and 27 unexposed subjects comprised interviews before the shift began and then at regular hourly intervals for the next six hours of the shift, four days in a row. Exposures were monitored concurrently with a personal real time aerosol monitor. Two different exposure profiles, a daily average and short term (15 minute) average, were used in the analysis. Exposure-response relations were evaluated by linking incidence rates for each symptom with categories of exposure. Acute incidence rates for nasal, eye, and throat irritation, and coughing and breathlessness were found to be associated with increased exposure levels of both exposure indices. Steeper exposure-response slopes were seen when short term exposure concentrations were used. Results from multivariate logistic regression analysis suggest that current smokers tended to be less sensitive to the exposure to airborne sodium borate dust. There was no indication that anhydrous sodium borate was more potent than the other sodium borates in this work environment.

The use of hypochlorite solutions in wound management

Hypochlorite solutions have been an issue of controversy for many years. Research has highlighted their harmful effects and yet doctors and nurses continue to use them. This article will review the literature both for and against the use of hypochlorite solutions and will examine alternative wound dressings.

Sealing ability of two intermediate restorative materials in bleached teeth

This study compared the radicular penetration of bleaching agents in endodontically treated teeth containing an IRM base, a Cavit base, and no base. Forty-five extracted human maxillary central incisors treated with conventional endodontic therapy with laterally condensed gutta percha and sealer were randomly divided into three groups: (1) Cavit base, (2) IRM base and (3) no base. In groups 1 and 2, a 3.5 mm thickness of base material was placed at the time of obturation. After storage in saline for 1 week, the teeth were bleached with a mixture of 35% hydrogen peroxide and sodium perborate, combined with a 10% methylene blue dye solution, using a combination thermocatalytic and non-thermocatalytic bleaching technique. The apical distance of dye penetration was measured. The control group demonstrated dye penetration to the apex, indicating that a base is required to prevent leakage of bleaching agents when this combination of bleaching techniques is used. The mean distance of leakage was 3.43 mm (+/- 1.14) for the Cavit group and 5.94 mm (+/- 1.72) for the IRM group. Analysis with a t-test revealed that Cavit was a more effective barrier to leakage than IRM (T = 4.20, P less than 0.001).

Effect of bleaching agents on inorganic components of human dentin and cementum

The effect of bleaching agents on the inorganic composition of human dentin and cementum was examined. Intact teeth were crushed, pulverized, and separated to dentin and cementum powders. The pulverized tissues were exposed to treatments with 30% H2O2, 3% H2O2, 2% sodium perborate in 30% H2O2, 2% sodium perborate in 3% H2O2, and 2% sodium perborate in bidistilled water for periods of 15 min and 1, 24, and 72 h. The degree of dissolution and the percentage of inorganic material for both dentin and cementum were measured. Thirty percent H2O2 and 2% sodium perborate in 30% H2O2 treatments significantly increased the solubility of dentin and cementum. The degree of dissolutions and the percentage of inorganic material remaining in the undissolved dentin and cementum increased with time progression. The greatest increase occurred with 30% H2O2 and 2% sodium perborate in 30% H2O2 after 24- and 72-h treatments. It is concluded that 30% hydrogen peroxide treatment may cause alteration in the chemical structure of the dentin and cementum making them more susceptible to degradation.

For and against Eusol

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pH variation among materials used for intracoronal bleaching

Intracoronal bleaching of pulpless teeth with 30% hydrogen peroxide may result in external cervical root resorption. One of several suggested etiological factors associated with this complication is the pH of the bleaching materials. Because the available data on the pH values of bleaching materials were conflicting, it was the purpose of this study to measure the pH of the materials commonly used for bleaching pulpless teeth. The pH of different concentrations of sodium perborate and 30% hydrogen peroxide, alone or in combination, were measured for a period of 14 days. Sodium perborate was confirmed to be alkaline, whereas 30% hydrogen peroxide was acidic. The pH of the materials when mixed together gradually changed from acidic to alkaline as the concentration of sodium perborate was increased. A thick clinical consistency mixture of both materials was alkaline, and its alkalinity increased with time. These results do not support the theory relating bleaching-induced root resorption to an acidic pH of the bleaching pastes.

An epidemiologic approach to the study of acute reversible health effects in the workplace

We present an epidemiologic approach for the study of the irritant effects of sodium borate exposure that can be used to study acute reversible health effects more generally. Acute irritant responses, such as symptoms of nasal irritation or cough, are subjective. They may, however, be accompanied by transient airway obstruction, which can be objectively measured by a change in peak expiratory flow (PEF) or forced expiratory volume in one second (FEV1). Because these physiologic responses are reversible and follow short-term peaks of exposure, they cannot be studied effectively using conventional epidemiologic methods of design and analysis. The proposed study design is a short-term prospective cohort study with frequently repeated measures of health effects and simultaneous measures of exposure. Because each subject passes through periods of high and low short-term exposure, the study has the form of a crossover design. This design permits each acute response to be linked to the corresponding short-term average exposure, providing the data necessary for dose-response analyses within subject. We present the results of the sodium borate study to illustrate the analysis of such data.

Oesophageal stricture following inadvertent ingestion of Steradent tablets in the elderly

Two cases of benign oesophageal stricture following the inadvertent ingestion of Steradent tablets are presented. We stress the particular risk of this problem occurring in the elderly population.

Respiratory effects of borax dust

The relation of respiratory symptoms, pulmonary function, and abnormalities of chest radiographs to estimated exposures of borax dust has been investigated in a cross sectional study of 629 actively employed borax workers. Ninety three per cent of the eligible workers participated in the study and exposures ranged from 1.1 mg/m3 to 14.6 mg/m3. Symptoms of acute respiratory irritation such as dryness of the mouth, nose, or throat, dry cough, nose bleeds, sore throat, productive cough, shortness of breath, and chest tightness were related to exposures of 4.0 mg/m3 or more, and were infrequent at exposures of 1.1 mg/m3. Symptoms of persistent respiratory irritation meeting the definition of chronic simple bronchitis were related to exposure among non-smokers. Decrements in the FEV1 as a percentage of predicted were seen among smokers who had heavy cumulative borax exposures (greater than or equal to 80 mg/m3 years) but were not seen among less exposed smokers or among non-smokers. Radiographic abnormalities were uncommon and were not related to dust exposure. Borax dust appears to act as a simple respiratory irritant and perhaps causes small changes in the FEV1 among smokers who are heavily exposed.

Gastric damage from ingested acid in children

Acid ingestion occurs relatively rarely and produces a spectrum of injury that is markedly different from the more commonly encountered alkaline burns of the oropharynx and esophagus. Gastric damage results from pylorospasm with pooling of the ingested caustic in a dependent location. Symptoms may be delayed for days or weeks. Perforation and/or strictures may require extensive gastric surgery. Early fiberoptic endoscopy is essential.