Sheldon L. Wagner

Practical and mathematical aspects of the problem of reconstructing objects from radiographs

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Skin cancer and water arsenic in lane county, Oregon

It was expected that the incidence of skin cancer would be related to the known high arsenic levels in water supplies of Lane County, Oregon. Incidence rates were based on all histopathologically confirmed cases among Lane County residents diagnosed during 1958–1971 and were compared to mean water arsenic levels measured during 1968–1974. Basal cell carcinoma had a mean annual incidence rate of 88 per 100,000, a 5:4::M:F sex ratio, and an increasing risk for both sexes in urban areas. Squamous cell carcinoma incidence was 50 per 100,000 and showed 2::1:M:F sex ratio but no urban predilection. Neither type of skin cancer was directly related to the arsenic levels as expected, although sporadic individuals with sufficient exposure could manifest the relationship. Fewer than expected drinking water sources were found to contain high arsenic content, so that the Lane County data do not necessarily contradict previous reports of positive correlation. The basal cell carcinoma pattern suggested that this disease might be potentiated by urban air pollutants.

Arsenic in blood and urine of forest workers as indices of exposure to cacodylic acid.

Five healthy forest workers exposed to cacodylic acid during a two-month period were observed for evidence of accumulation of arsenic in the blood, the pattern of its urinary excretion, and signs of clinical toxicity. Urinary arsenic appeared to constitute an index of exposure, with excretion levels increasing within one week. Blood levels were found to correlate poorly with exposure. Worker education and proper safety precautions in clothing must be emphasized. Arsine gas in treated forest areas may be potentially dangerous to forest workers.

Skin Cancer and Arsenical Intoxication From Well Water

A case of acute arsenical intoxication arising from ingested well water containing only 1.2 ppm of arsenic is reported. After a latent period of 14 years, multiple cutaneous basal cell carcinomas developed. The water was analyzed for a variety of other trace elements and compounds and no evidence for the existence of other carcinogens was found. This study strengthens the concept that arsenic is a carcinogen. The role of a possible selenium deficiency is also discussed.

Residues of pentachlorophenol and other chlorinated contaminants in human tissues: Analysis by electron capture gas chromatography and electron capture negative ion mass spectrometry

Samples of human tissues including testes, kidneys, prostate glands, livers, and adipose tissues removed at autopsy were analyzed for pentachlorophenol (PCP) and nonachloro-2-phenoxyphenol (NCPP); the fat samples were also analyzed for other chlorinated contaminants. Electron capture gas chromatography was used to quantitate the residues after isolation and cleanup. Identity of the residues was confirmed by electron capture negative ion mass spectrometry. All tissues analyzed for PCP tested positive with a range from 0.007 ppm (μg/g) in subcutaneous fat to 4.14 ppm in testis. Residues of NCPP were much lower, ranging from levels below the detection limit to 0.59 ppm in testis. The highest average residues, based on the lipid content of the tissue, of PCP (1.09 ppm) and of NCPP (0.19 ppm) were found in testis followed by kidney (0.95 ppm PCP), prostate (0.84 ppm PCP), and liver (0.59 ppm PCP). Residues of these chemicals in the adipose tissues were on the average about 40 times lower than the residues in the non-fatty tissues. Other chlorinated contaminants found in the subcutaneous fat included hexa-, hepta-, and octa-chlorodibenzo-p-dioxins at sub-ppb levels and DDE averaging 2.47 ppm.

Acute accidental lindane ingestion in toddlers

Lindane toxicity has been reported to occur mostly by way of dermal exposure. Cases of ingestion in which blood levels have been determined are rare. We present three such cases, along with a comparison of cases in the literature with respect to blood level half-lives and correlation with signs of toxicity. Emergency physicians can prevent acute ingestion by educating patients on the proper use of lindane and by selecting less toxic scabicidal agents.

Addendum to “Practical and mathematical aspects of the problem of reconstructing objects from radiographs”

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The Diagnosis of Breast Cancer in Mammograms by the Evaluation of Density Patterns

Standard mammograms from 33 patients with surgically proved adenocarcinoma or fibrocystic disease were analyzed with a scanning microdensitometer and computer. A quickly computable number called the linear mass ratio is introduced. This simple ratio discriminated correctly between the 16 adenocarcinomas and 17 fibrocystic lesions of the study, all cases in which diagnosis had required biopsy.

Influence of menstrual cycle on serum cholinesterase.

This study examined whether the variability in cholinesterase (ChE) values among and within women may be attributed to phase of menstrual cycle and/or circulating progesterone concentration. Blood was drawn from 21 female subjects once a week for 8 weeks and analyzed for ChE activity and for progesterone concentration. Women ranged in age from 25 to 55 years and five used exogenous hormones (oral contraceptives, estrogen supplements, or progesterone therapy); one woman became pregnant during the study. There was a significant positive correlation between serum ChE and progesterone values only for the two women on oral contraceptives although there were large weekly variations within individuals (CV: 4-32%). Age significantly affected ChE values with 36-40 year olds having the lowest values and 30-35 year olds the highest. This variation in serum ChE probably is due to the influence of some sex steroid but, in women, there is not a direct one-to-one relationship between the enzyme and progesterone. However, when interpreting ChE tests used to monitor exposure of women to pesticides age and hormone intake must be considered in order to avoid false positive results.

Reconstruction from X-Rays

According to T.J. Rivlin (these Proc.) “The problem of optimal recovery is that of approximating as effectively as possible a given map of any function known to belong to a certain class from limited and possibly error-contaminated information about it.” More precisely, in the scheme envisioned by Rivlin there are given spaces X of possible objects, Y of possible data, and Z of possible reconstructions of certain features of the objects.