Characterizations and morphology of sodium tungstate particles

A solid-state reaction technique was used to synthesize polycrystalline Na₂WO₄. Preliminary X-ray studies revealed that the compound has a cubic structure at room temperature. The formation of the compound has been confirmed by X-ray powder diffraction studies and Raman spectroscopy. Electrical and dielectric properties of the compound have been studied using complex impedance spectroscopy in the frequency range 209 Hz-1 MHz and temperature range 586-679 K. The impedance data were modellized by an equivalent circuit consisting of series of a combination of grains and grains boundary. We use complex electrical modulus M* at various temperatures to analyse dielectric data. The modulus plots are characterized by the presence of two relaxation peaks thermally activated. The morphologies and the average particle size of the resultant sodium tungstate sample were demonstrated by atomic force microscopy, scanning electron microscopy and transmission electron microscopy. The thicknesses and optical constants of the sample have been calculated using ellipsometric measurements in the range of 200-22 000 nm by means of new amorphous dispersion formula which is the objective of the present work. The results were obtained for Na₂WO₄ particles from experimental (EXP) and measured (FIT) data showed an excellent agreement. In addition, the energy gap of the Na₂WO₄ sample has been determined using ellipsometry and confirmed by spectrophotometry measurements.

Cancer in ex-asbestos cement workers in Israel, 1953-1992

A cohort of 3,057 male workers employed in an asbestos-cement plant using 90% chrysotile-10% crocidolite, located in Northern Israel, was followed from 1953-1992 for incidence and mortality from cancer. In the years 1978-1992, the cohort had an elevated risk for all malignant neoplasms combined (n = 153, SIR = 117, ns), lung cancer (n = 28, SIR = 135, ns), mesothelioma (n = 21; SIR > 5000, p < .0001), unspecified pleural cancer (n = 5; SIR = 278, P < .0001), and liver cancer (n = 7, SIR 290, ns). Risks for colo-rectal (n = 19; SIR = 79, ns), bladder (n = 12, SIR 69) and renal cancers (n = 5, SIR 104) were less than expected. Risk for mesothelioma showed a sharp risk gradient with duration of exposure, increasing from 1 per 625 for those employed less than 2 years to 1 per 4.5 workers employed over 30 years. The ratio of mesothelioma to excess lung cancer cases was 2.9 to 1, or 3.6 to 1, if pleural cases of unspecified origin were included; the pleura to peritoneum ratio of verified mesothelioma cases was 20 to 1. This atypically high ratio of mesothelioma to excess lung cancer cases is suggested to be the combined result of high past asbestos exposures in the workers and their low prior risk for lung cancer, and possibly, relatively early smoking cessation in relation to asbestos exposure.

Prenatal and postnatal studies of a late infantile GM2 gangliosidosis in a family of Syrian origin: a possible B1 variant

We describe late infantile Tay-Sachs disease with high residual hexosaminidase A activity in two siblings of a Syrian Druze family. The patients' leukocytes had 26% of normal hexosaminidase A activity when tested with the conventional fluorogenic substrate 4-methyl-umbelliferyl-2-acetamido-2-deoxy-beta-D-glucopyranoside (4-MUG) and only about 10% when assayed with the sulfated substrate, 4-methyl-umbelliferal- beta-N-acetyl-glucosamine-6-sulfate (4-MUGS). According to the standard procedure of the heterozygote screening program (employing 4-MUG and heat inactivation), the parents were not diagnosed as an at-risk couple since the father was classified as a noncarrier. However, both parents' levels were clearly within the carrier range on the basis of 4-MUGS. The unique catalytic characteristics of the patients' enzyme forward the assumption that the affected sibs are B1 variants. The parents' enzymatic levels, together with their known consanguinity, might indicate that these patients are homozygotes for the rare mutation and not genetic compounds as has been documented for most of the infantile B1 variants. To the best of our knowledge this is the first reported case of B1 variant in a child of that extraction.

Mesothelioma mortality among former asbestos-cement workers in Israel, 1953-90

Asbestos workers have long been recognized as a high risk group for the development of mesothelioma and other cancers. In this study we collated from a variety of sources 26 mesothelioma deaths that occurred between 1978 and 1990 among a cohort of some 4,441 former workers from an asbestos-cement plant in northern Israel. Since the expected number of deaths for this number of Israeli males in this age-group over this period is 0.12 cases, the risk of this disease was more than 223 times the national rate, age and sex adjusted [standardized mortality ratio (SMR) = 22,351, P < 0.001]. The mean years of exposure of persons who died from mesothelioma was 16.2 (SE 2.5). The mean latency period for mesothelioma cases from onset of exposure to death was 25.6 years (SE 1.3). Additional follow-up systems are needed to ensure complete reporting of asbestos-related diseases, including epidemiologic follow-up of asbestos-exposed workers after cessation of their work, with regular analysis of death and cancer registry data for high risk groups. Asbestos-related cancer is an important element in cancer epidemiology that requires further development in Israel. Studies of former workers, their families and of persons who worked or attended school adjacent to the asbestos-cement factory, as well as follow-up of other former worker groups exposed to asbestos are recommended.

An epidemic of waterborne Shigella gastroenteritis in Kibbutzim of western Galilee in Israel

In an epidemic of Shigella sonnei gastroenteritis, probably waterborne, 1216 people were affected within three weeks, 302 of them members of communal settlements, the kibbutzim. A descriptive study of the epidemic in six affected kibbutzim in the area showed that the highest rates of diarrhoea occurred in a kibbutz that received its drinking water solely from the allegedly contaminated well. People at high risk within the kibbutzim were temporary visitors from Europe and the US (the volunteers), children aged 1 to 5 years, adult women, and children and their mothers in kibbutzim where the sleeping arrangements for the children was in 'children's houses'.

An outbreak of typhoid fever due to contamination of the municipal water supply in northern Israel

An outbreak of typhoid fever followed a large outbreak of dysentery in northern Israel. Both outbreaks resulted from contamination of a drilled well that supplied water to the municipal water system. The well was contaminated with sewage from a broken main-pipe coming from Shefaram (an Arab town). The outbreak of typhoid involved 77 persons, of whom 75 were hospitalized. In 67, phage-type C1 (the phage type dominant in Shefaram since the 1950s) was isolated. The incubation period was relatively long, between 12 and 40 days (median 22) following exposure. Over 50% of the cases were children aged 0 to 14, and only two patients were older than 35 years; the sex ratio among the patients was 1:1. The incidence rate in Shefaram was 2.3 times higher than in the Krayot (outlying suburbs of Haifa). This difference was due mainly to the high incidence in young females in Shefaram. The opposite was observed during the outbreak of dysentery, when the attack rates of the disease were higher in the Krayot. Relapses occurred in 12% (9 cases). This outbreak demonstrates the potential that still exists for serious outbreaks due to contamination of the municipal water supply.