Formaldehyde and methylene glycol equivalence: critical assessment of chemical and toxicological aspects

Due largely to the controversy concerning the potential human health effects from exposure to formaldehyde gas in conjunction with the misunderstanding of the well-established equilibrium relationship with its hydrated reaction product, methylene glycol, the concept of chemical equivalence between these two distinctly different chemicals has been adopted by regulatory authorities. Chemical equivalence implies not only that any concentration of methylene glycol under some condition of use would be nearly or completely converted into formaldehyde gas, but also that these two substances would be toxicologically equivalent as well. A relatively simple worst case experiment using 37% formalin (i.e., concentrated methylene glycol) dispels the concept of chemical equivalence and a review of relevant literature demonstrates that methylene glycol has no inherent toxicity apart from whatever concentration of formaldehyde that might be present in equilibrium with such solutions.

Scenario analysis of alternative vegetation management options on the greenhouse gas budget of two grazing businesses in north-eastern Australia

The emerging carbon economy will have a major impact on grazing businesses because of significant livestock methane and land-use change emissions. Livestock methane emissions alone account for ~11% of Australia’s reported greenhouse gas emissions. Grazing businesses need to develop an understanding of their greenhouse gas impact and be able to assess the impact of alternative management options. This paper attempts to generate a greenhouse gas budget for two scenarios using a spread sheet model. The first scenario was based on one land-type ‘20-year-old brigalow regrowth’ in the brigalow bioregion of southern-central Queensland. The 50 year analysis demonstrated the substantially different greenhouse gas outcomes and livestock carrying capacity for three alternative regrowth management options: retain regrowth (sequester 71.5 t carbon dioxide equivalents per hectare, CO2-e/ha), clear all regrowth (emit 42.8 t CO2-e/ha) and clear regrowth strips (emit 5.8 t CO2-e/ha). The second scenario was based on a ‘remnant eucalypt savanna-woodland’ land type in the Einasleigh Uplands bioregion of north Queensland. The four alternative vegetation management options were: retain current woodland structure (emit 7.4 t CO2-e/ha), allow woodland to thicken increasing tree basal area (sequester 20.7 t CO2-e/ha), thin trees less than 10 cm diameter (emit 8.9 t CO2-e/ha), and thin trees <20 cm diameter (emit 12.4 t CO2-e/ha). Significant assumptions were required to complete the budgets due to gaps in current knowledge on the response of woody vegetation, soil carbon and non-CO2 soil emissions to management options and land-type at the property scale. The analyses indicate that there is scope for grazing businesses to choose alternative management options to influence their greenhouse gas budget. However, a key assumption is that accumulation of carbon or avoidance of emissions somewhere on a grazing business (e.g. in woody vegetation or soil) will be recognised as an offset for emissions elsewhere in the business (e.g. livestock methane). This issue will be a challenge for livestock industries and policy makers to work through in the coming years.

The possible effects of environmental estrogen disrupters on reproductive health

The term environmental estrogen refers to chemical substances that exhibit some degree of estrogen-like activity. The primary emphasis for potential adverse effects resulting from exposure to environmental estrogens is on in utero exposure because such exposures can occur during critical periods of organogenesis. Assessment of biological plausibility can be based, in part, on the extensive data on the effects of diethylstilbestrol (DES). The available evidence is too limited to judge with any confidence whether sperm counts have declined during the past 50 years. Based on both animal and human data with DES, it is biologically plausible that in utero exposures to exogenous estrogenic compounds are capable of reducing sperm production in adult men. However, the apparent existence of a maternal dose threshold for DES-induced effects on sperm count undermines the likelihood that environmental estrogens, which are substantially less potent, are capable of causing similar effects.

Psychobiological markers of stress in pregnancy: 6-sulfatoxymelatonin--a longitudinal study

Maternal stress, physical and psychological, has been associated with adverse pregnancy outcome. The pineal gland is a physiological transducer that reflects adrenergic input. In a recent pilot study, we found urinary 6-sulfatoxymelatonin, the melatonin metabolite, to be elevated after a women spent a day at work compared to levels after a day off work, a leisure day. To evaluate the value of melatonin as a marker of stress, we evaluate melatonin metabolite levels in 121 women, along with perceived anxiety levels and urinary cortisol. Urinary cortisol and maternal anxiety levels each were significantly higher after a work day compared to a leisure day p = .03 and p = .001, respectively. 6-Sulfatoxymelatonin was not significantly different between work and leisure. Changes in cortisol levels were correlated with changes in melatonin metabolite levels (r = .62, p = .001). There was no correlation between changes in anxiety between work and leisure and changes in 6-sulfastoxymelatonin. We found no correlation with 28 week 6-sulfatoxymelatonin or 28-week cortisol and birth weight or gestational age at delivery. Results of this study suggest that melatonin secretion may not be a valuable marker for stress in pregnancy.

New approaches for estimating risk from exposure to diethylstilbestrol

A subgroup from a National Institute of Environmental Health Sciences, workshop concerned with characterizing the effects of endocrine disruptors on human health at environmental exposure levels considered the question, If diethylstilbestrol (DES) were introduced into the market for human use today and likely to result in low-dose exposure of the human fetus, what would be required to assess risk? On the basis of an analysis of the quality of data on human DES exposure, the critical times and doses for inducing genital tract malformations and cancer must be determined. This would be facilitated through analysis of the ontogeny of estrogen receptor expression in the developing human genital tract. Models of low-dose estrogenic effects will have to be developed for human and rodent genital tract development. Mouse models offer many advantages over other potential animal models because of the wealth of the earlier literature, the availability of sensitive end points, the availability of mutant lines, and the possibility of generating genetically engineered model systems. Through multidisciplinary approaches, it should be possible to elucidate the cellular and molecular mechanisms of endocrine disruption elicited by estrogens during development and facilitate an assessment of risk to humans.

Rising risk of testicular cancer by birth cohort in the United States from 1973 to 1995

PURPOSE

Recent epidemiological studies have demonstrated an increasing incidence of testicular cancer in white men which appears to be correlated with the period of birth. Because this birth cohort phenomenon can explain etiological factors in testicular cancer, we determine whether this trend is present throughout the United States based on an analysis of testicular cancer incidence by birth cohort.

MATERIALS AND METHODS

Testicular cancer incidence was obtained from the National Cancer Institute Surveillance, Epidemiology and End Results database from 1973 to 1995. Numbers of cases were extracted and grouped by 5-year birth cohorts for all testicular germ cell neoplasms. Poisson regression analysis with variables of age, time of diagnosis and birth cohort were used to determine relative risk. Poisson models were compared using computer log linear model software.

RESULTS

Between 1973 and 1995 the incidence of testicular cancer in the United States increased 51% (3.61 to 5.44/100,000). Analysis of Poisson models revealed that birth cohort was strongly associated with relative risk of testicular cancer (p = 0.001). In addition, peak age at diagnosis decreased for each successive birth cohort.

CONCLUSIONS

The overall incidence of testicular cancer in white men and the relative risk of testicular cancer have been increasing in the United States. This trend is strongly associated with birth cohort in concordance with previously reported European data. Moreover, testicular cancer is being diagnosed at a younger age as evidenced by a shift to the left in the age of peak incidence. These unique epidemiological patterns offer a basis for analysis of potential etiological factors.

The "equal environments assumption" in MZ-DZ twin comparisons: an untenable premise of psychiatric genetics?

The comparison of MZ-DZ twins in behavioral genetics has produced what seems like irrefutable evidence for the heritability of many psychiatric disorders. But such research depends on the validity of the EEA--the "equal environments assumption"--as an underlying premise. In this paper, several empirical studies which support the EEA are critically reviewed in terms of methodology and the way data has been processed in a mathematical model called "path analysis". It turns out that studies investigating the EEA appear to be largely inadequate in terms of technique, as well as biased in the inferences drawn. Further, the "heritability" estimate--often taken to mean the influence of trait-specific genes--is merely a statistical abstraction derived from a matrix of correlations; this estimate encompasses many buried environmental effects so that "heritability" does not correspond to any underlying DNA structure. In conclusion, many MZ-DZ pedigree studies have dubious scientific value, given the non-viable premise of the EEA, as well as the misleading operational definition of what has been called "heritability".

Dementia and Alzheimer's disease. Indications, diagnosis, and treatment

At least 6 million Americans suffer from some form of dementia. More than half of those patients are afflicted with Alzheimer's disease, a progressive, degenerative neurological disorder. Reaching the diagnosis of Alzheimer's, however, is often difficult since Alzheimer's can be accurately diagnosed only after all other options are ruled out. The process is painstaking, but it's also the crucial link in ensuring proper diagnosis and treatment. There's no cure yet for Alzheimer's, but researchers are narrowing in on possible causes of the disease and identifying patients who may be predisposed to developing it. Some of the most compelling research focuses on the presence of one or more of the apolipoprotein E4 genes. Researchers also continue to develop new drugs and physical therapies. In the Twin Cities, several drug studies are underway, and community resources are available to provide Alzheimer's patients and their families with information on everything from support groups to assisted-living arrangements.

An unusual gastrointestinal presentation of leishmaniasis

While visceral leishmaniasis (VL) generally occurs in immunocompetent subjects in endemic areas, it has been increasingly recognised as an important opportunistic infection in the immunocompromised including those infected with the human immunodeficiency virus. We report an unusual presentation of visceral leishmaniasis in a patient with the acquired immunodeficiency syndrome (AIDS) with disease which appeared to be limited to the gastrointestinal tract.

Visceral leishmaniasis in HIV infection and AIDS: clinical features and response to therapy

The development of visceral leishmaniasis with atypical features in an AIDS patient, and the recent flurry of reports of visceral leishmaniasis in HIV-infected individuals prompted the review of its manifestations in the 47 reported cases. Splenomegaly, which is almost always a feature of visceral leishmaniasis in the immunocompetent host, was absent in eight. Antibodies to Leishmania donovani, which are present in approximately 95 per cent of immunocompetent patients with visceral leishmaniasis, were absent in 29 of 45 (66 per cent) of HIV-infected patients tested. Nine HIV-positive patients with visceral leishmaniasis did not exhibit a primary clinical response to therapy with antimonials and of those who did show a response, relapse occurred in 13, at a mean 4.5 months after stopping therapy. Seventeen patients are known to have died often in association with respiratory disease; Leishmania was seen in one bronchial lavage specimen and in lung tissue in one post-mortem performed. In order to improve the prognosis of visceral leishmaniasis in HIV-infected patients diagnosis will have to be made earlier, taking account of the atypical features, and treatment will need to be improved, both initially and perhaps also by the use of long-term maintenance therapy.

Alzheimer's disease: a correlational analysis of the Blessed Information-Memory-Concentration Test and the Mini-Mental State Exam

We carried out a correlational analysis of the scores on the Blessed Information-Memory-Concentration Test and the Mini-Mental State Exam in 40 subjects with Alzheimer's disease. The average product moment correlation coefficient between the two tests on repeated administration over 6 weeks ranged from -0.73 to -0.83. Both tests demonstrated test-retest reliability coefficients of 0.75 and above. A formula was developed to convert one test score to the other.

Amyloidosis secondary to drug abuse and chronic skin suppuration

Amyloidosis has not been included in the wide spectrum of medical complications associated with drug abuse. Chronic visceral infection is a recognized cause of amyloidosis, but chronic suppuration of the skin is not a well-appreciated cause of this condition. Furthermore, to our knowledge, chronic skin suppuration secondary to parenteral drug abuse has not been reported as a cause for systemic amyloidosis. We report a case in which subcutaneous injections of narcotic tablets led to chronic skin suppuration and systemic amyloidosis.

Model for the calculation of output for elongated fields at nonstandard distances for a 25-MV betatron and for radiocobalt teletherapy units

Output-area factors are usually provided only for square fields at one standard distance. To calculate dose for mantle, extended field, total nodal, subtotal body, and total body irradiation, output-area factors are required for a continuous range of shapes and distances. Dose rate measurements have been made for different elongation ratios at various distances with an Allis-Chalmers 25-MV betatron, an AECL Theratron-80 60Co unit, a Picker C-9 60Co unit, and a Picker C-10000 60Co unit. A model is presented that permits the extension of dose rates and area factors for square fields at one distance to elongated fields at any distance. An illustrative calculation for one of the units is given.

Advances in Diagnosis of Digestive Tract Diseases

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