Topical treatments for hydrofluoric acid dermal burns. Further assessment of efficacy using an experimental piq model.

Several topical treatments for hydrofluoric acid dermal burns (Zephiran, calcium acetate and magnesium hydroxide antacid soaks, and calcium gluconate gel) were assessed for efficacy in a pig model. Gross appearance and histopathology of treated and untreated burn sites were evaluated. For superficial burns, Zephiran was most effective; calcium acetate, magnesium hydroxide antacid, and calcium gluconate gel were less effective. For deep burns, gross observations showed that calcium acetate and Zephiran were most efficacious, whereas histopathology indicated comparable efficacy of Zephiran, calcium acetate, and calcium gluconate gel for all skin layers. Magnesium hydroxide antacid demonstrated efficacy only for the subdermis. The clinically beneficial effects of both Zephiran and calcium gluconate gel were affirmed. Although results suggest that calcium acetate and magnesium-containing antacids may be beneficial for human hydrofluoric acid dermal burns, these are not established clinical treatments.

Hydrofluoric acid dermal burns. An assessment of treatment efficacy using an experimental pig model.

There currently exist various opinions concerning the best therapy for managing hydrogen fluoride (HF) dermal burns. Previously reported animal studies designed to evaluate the efficacy of certain therapies are not completely convincing. Studies initially were conducted to develop a reliable animal model for assessing efficacy of treatment. Evaluation of several animal species, dosing regimens (HF concentrations, exposure periods), and application techniques showed that the most consistent and reproducible dermal lesions were produced with 38% HF applied to the skin of anesthetized pigs for exposures of 9, 12, or 15 minutes using Hill Top Chamber patches. Using this model, the efficacy of six clinically applicable treatments was assessed by subjectively scoring and statistically analyzing photographic and histopathological data obtained from treated and untreated control lesions. Photographic data analysis ranked treatments with respect to effectiveness as follows: iced Zephiran and 10% calcium acetate soaks--highly effective; 2.5% calcium gluconate gel, 5.0% calcium gluconate injection and iced Hyamine soaks--effective; 10% calcium gluconate injection--ineffective. Histopathological data analysis showed the topical treatments (2.5% calcium gluconate gel, iced Hyamine, or iced Zephiran soaks) to be most effective in reducing superficial epidermal damage, and the 5% calcium gluconate injection or 10% calcium acetate soaks to be beneficial to deeper tissues of the dermis and subdermis. Injection of 10% calcium gluconate was ineffective. This study suggests that the anesthetized pig model has good applicability for assessing efficacy of HF dermal burn therapies. In addition, it indicates that further experimentation with 10% calcium acetate soaks is warranted.

Cancer II. Distortions in standardized rates.

Age-adjustment (standardization), the statistical method most used by cancer epidemiologists to express incidence and mortality rates, makes use of an arbitrarily chosen "standard" population to calculate rates that are in reality only abstract index numbers. It is generally known that the "age" of any standard population affects the magnitude of the index, but it is not widely recognized that the use of U.S. Censuses as standards, possibly excepting the 1930 U.S. Census population, distorts the index number. The greater the disparity between the numbers of males and females in middle-aged groups and older, the greater is the distortion. Hence sex as well as age distribution in a standard must be considered if rates are to be expressed in terms of sex. Trends of cancer incidence or mortality will have different slopes depending on the census year chosen as a standard; yet no standard can arbitrarily be called the "correct" one. Age-, race-, and sex-specific rates are more precise and can be made to give considerably more meaningful description of cancer trends, albeit their use requires scrutiny of a greater assortment of numbers.

Cancer: I. Analysis of recent new case incidence reports.

Provides an evaluation of recent government agency reports that allege an upward trend in cancer incidence. Visual and statistical analyses are performed to demonstrate that the data of two cancer surveys, TNCS and SEER, which cover discontinuous time periods and non-identical geographic populations, are incompatible. They may not, as they were, be pooled for time-trend analysis. There is misstatement of the population-at-risk in the use of TNCS data. In SEER, there is evidence that procedures have changed over time, that updating procedures have a sex bias, and that the findings are not yet sufficiently stable to provide a meaningful trend assessment. The alleged upward trend in cancer incidence is an illusion attributable to the overlooking of the discrepancies and inconsistencies between and within the two surveys. Neither survey individually shows an increase in cancer incidence.