Dental personnel manually handle products that contain monomers. Several studies have documented adverse health effects after exposure to such products. Gloves made of vinyl or latex are easily penetrated by monomers. Ordinary glasses, or visors, do not protect against vapour from polymer products. Dental face masks filter out about 40% of respirable particles. To survey the prevalence of asthma, atopic dermatitis, conjunctivitis, hay fever/rhinitis, and hand eczema among dental personnel, a questionnaire was distributed to all dental teams in Northern Sweden. Referents were researchers, teachers, and secretaries from the same geographical area. The response rate was 76% for dental teams, and 66% for referents. The results show a significantly higher prevalence of conjunctivitis, and atopic dermatitis among dentists, both male and female. Hypersensitivity to dental materials was reported by significantly more dental personnel than by referents.
The frequency and character of early complications following creation of enterostomies, and their relation to the applied suture material, were studied in 50 consecutive patients. The stomas were matured by mucocutaneous eversion and were fixated with Maxon (Davis & Geck, Pearl River, NY) 4-0 and Vicryl (Ethicon, Inc., Somerville, NJ) 3-0 sutures. Half of the stoma circumference was sutured with one suture type, and vice versa. Three patients died within 10 days. Of the remaining 47 patients, 34 (72 percent) had one or more complications diagnosed. Four (9 percent) suffered major complications (one total stoma loosening and three partial stoma necroses), and 30 (64 percent) had mucocutaneous affections only. There was no statistically significant correlation between enterostomy type or surgical procedure and complications, whereas the incidence of mucocutaneous complications was significantly higher following fixation with Vicryl as compared with Maxon sutures. The cause of this difference is uncertain; however, the physical configuration of the sutures, Maxon being monofile vs. Vicryl being braided, seems important. Whether the chemical structure is significant as well remains undetermined at present.
The author summarized systematically errors, hazards, difficulties and complications encountered in esophageal alloplasty. An analysis of 50 clinical observations (diverticulectomy, intubation of the esophagus in inoperable cancers, recanalization of stenosed entero-esophageal anastomoses after esophagoplasty, intubation of the enteroesophageal anastomosis in cancer recurrence after gastrectomy, previously performed) and 260 experiments on dogs (autoalloplasty of terminal and segmental portions of the esophagus) is given. Some measures for prevention of possible complications are recommended.
Exposure to persistent organochlorines in breast milk was estimated probabilistically for Canadian infants. Noncancer health effects were evaluated by comparing the predicted exposure distributions to published guidance values. For chemicals identified as potential human carcinogens, cancer risks were evaluated using standard methodology typically applied in Canada, as well as an alternative method developed under the Canadian Environmental Protection Act. Potential health risks associated with exposure to persistent organochlorines were quantitatively and qualitatively weighed against the benefits of breast-feeding. Current levels of the majority of contaminants identified in Canadian breast milk do not pose unacceptable risks to infants. Benefits of breast-feeding are well documented and qualitatively appear to outweigh potential health concerns associated with organochlorine exposure. Furthermore, the risks of mortality from not breast-feeding estimated by Rogan and colleagues exceed the theoretical cancer risks estimated for infant exposure to potential carcinogens in Canadian breast milk. Although levels of persistent compounds have been declining in Canadian breast milk, potentially significant risks were estimated for exposure to polychlorinated biphenyls, dibenzo-p-dioxins, and dibenzofurans. Follow-up work is suggested that would involve the use of a physiologically based toxicokinetic model with probabilistic inputs to predict dioxin exposure to the infant. A more detailed risk analysis could be carried out by coupling the exposure estimates with a dose-response analysis that accounts for uncertainty.
Hand dermatitis among dental personnel has been an issue in recent years. Dental personnel manually handle polymer materials which are known to irritate skin, and also cause allergy. In addition, dental personnel wash their hands frequently, and use latex gloves, and are therefore at risk to develop hand dermatitis. To survey the occurrence of hand dermatitis among dental personnel, questionnaires were sent to all dental teams (dentist + chair assistant) working in the two northern Swedish counties. Referents were; researchers, teachers, and secretaries from a university and high schools, from the same geographical area. The response rate was 76% for dental teams, and 66% for referents. The results show that male dentists reported a significantly higher prevalence of hand dermatitis than male reference. In contrast to chair assistants and referents, dentists (both male and female) reported a higher extent of hand dermatitis on the left than on the right hand. There was an association between hand dermatitis among dental personnel and; age, eczema in childhood, and hay fever but, not with; sex, asthma, frequent washing of the hands, and glove use. Whitening of the fingers increased with increasing age among dental personnel. Pricking was also associated with frequent glove use. Pricking of the fingers was associated with sex, and 3.5 times more common among female dental personnel than male dentists. Numbness of the fingers, and finger pain was reported by more dentists than chair assistants and referents.
A total of 25 146 workers at 13 plants producing man made mineral fibres (MMMF) in seven European countries (Denmark, Finland, Federal Republic of Germany, Italy, Norway, Sweden, and United Kingdom) were studied in a historical cohort investigation. At 12 of the 13 plants an environmental survey was carried out to determine present day concentrations of airborne man made mineral fibres that showed levels of respirable fibres usually below 1 f/ml and most commonly in the range 0.01 to 0.1 f/ml. Workers were entered into the cohort at the moment of their first employment at one of the 13 factories (which started to operate between 1900 and 1955), and were followed up to at least 31 December 1977. Three per cent of the workers were lost to follow up. National death rates and national cancer incidence rates, where applicable, were used for each of the seven countries for comparison with the workers' cohort. A single death from mesothelioma was reported out of a total of 309 353 person-years of observation. No consistent differences (within and between plants) were noted between observed and expected numbers concerning individual causes of death or individual cancer sites, apart from lung cancer. For this cause a tendency was observed for the standardised mortality ratio (SMR) to increase with time from first employment. When the data from all the plants were pooled a statistically significant raised SMR of 192 (17 observed, 8.9 expected; 95% confidence interval 117-307) appeared in the group with 30 years or more since first employment. The relevance of this finding, to which different factors including uncontrolled confounders such as smoking habits may have contributed, cannot be established at present. The result is suggestive, however, of an increased risk associated with the man made mineral fibres working environment of 30 or more years ago.
Contact allergy to phenol-formaldehyde resins (PFRs) based on phenol and formaldehyde is not detected by a p-tertiary-butylphenol-formaldehyde resin (PTBP-FR) included in most baseline patch test series.
To investigate the rate of contact allergy to PFR-2 (a mixture of monomers and dimers from a resol resin based on phenol and formaldehyde) in a Swedish population, and to investigate associated simultaneous allergic reactions.
Five centres representing the Swedish Contact Dermatitis Research Group included PFR-2 in their patch test baseline series for a period of 1.5 years.
Of 2504 patients tested, 27 (1.1%) reacted to PFR-2. Of those 27 individuals, 2 had a positive reaction to formaldehyde and 2 to PTBP-FR. Simultaneous allergic reactions were noted to colophonium in 6, to Myroxylon pereirae in 14, and to fragrance mix I in 15.
The contact allergy frequency in the tested population (1.1%) merits its inclusion in the Swedish baseline series and possibly also in other baseline series. Simultaneous allergic reactions were noted to colophonium, M. pereirae, and fragrance mix I.
PURPOSE: The aims of this thesis were: 1. To study the effect of water and pH on composite resin materials in vitro by assessing sorption, solubility, monomers eluted and flexural properties. 2. To study adverse effects on the skin in dentists possibly caused by acrylic resin-based materials. MATERIALS AND METHODS: Proprietary composite resin materials were used for the in vitro experiments. The tests were performed according to the ISO 4049 (1988) with the exception of McIlvaine's solution used in Study II and the storage times. The analysis of eluted monomers was performed using HPLC. The flexural properties were tested in a three-point bending equipment. The secant modulus and deflection at break were calculated for description of the viscoelastic behaviour of the material tested. To study the adverse effects on skin in dentists, a questionnaire was sent to 3500 randomly selected Swedish dentists. A response rate of 88% was achieved and the data were statistically analysed and compared with the results of two studies on skin symptoms among the general Swedish population. Dentists living in the three main cities in Sweden who had experienced hand eczema during the last 12 months were invited to a clinical examination in which a patch test was included. RESULTS: A wide range in sorption and solubility over the test period was found, with low sorption values observed for materials containing hydrophobic matrix monomers. A maximum concentration of monomers eluted was found after 7 days of storage, and TEGDMA was the main monomer released. pH affected the sorption and solubility behaviour for two of the three materials tested. The flexural strength and modulus of the composite resin material were lowered after water storage and the secant modulus and deflection at break could describe the viscoelastic behaviour. The prevalence of dry skin and hand eczema was high in dentists compared to two age-matched general population samples investigated using identical questions. The most important predictor for adult hand eczema was found to be childhood eczema. At the clinical examination, irritant contact dermatitis was the predominant diagnosis. Seven per cent reported skin symptoms when working with acrylic resin-based material but the true prevalence of hand eczema caused by acrylates was below 1%. Contact allergy was diagnosed, however, in 50% of the dentists, mainly due to other allergens such as nickel, perfumes or rubber chemicals. CONCLUSIONS: The matrix composition was shown to be important for the sorption and solubility behaviour of the composite resin materials tested and a maximum release of monomers occurred after 7 days of storage. pH affected the water sorption and solubility behaviour. Calculation of the secant modulus and the deflection at break allowed the plasticising effect of water on composite resin material to be observed. The prevalence of hand eczema was high among dentists, with irritant contact dermatitis as the predominant diagnosis. Childhood eczema was the most important predictor for adult hand eczema. The prevalence of hand eczema owing to acrylates was below 1%.