Environment and the skin.

The skin is an important interface between man and his environment; it is an important portal of entry for hazardous agents and a vulnerable target tissue as well. It is a uniquely accessible model system for detecting hazards and for studying mechanisms of a wide variety of biologic funcitons. Environmental causes of skin reactions comprise a vast array of physical, chemical and biological agents. To appreciate the role of the skin as an interface with man's environment, it is necessary to understand the multiple adaptive mechanisms, and the defenses of the skin against the environmental stresses. The skin is endowed with a versatile group of defenses against penetration, fluid loss from the body, thermal stress, solar radiation, physical trauma and microbial agents. Patterns of adverse response range in quality and intensity from uncomplicated itching to metastatic neoplasia. Environmental problems comprise a large segment of disabling skin disease. Although critical epidemiologic data is limited, cutaneous illnesses comprise a significant segment of occupational disease. This represents a significant loss in productivity and a major cause of disability. The most serious research needs include the development of surveillance systems for identifying skin hazards and determining frequency of environmental skin disease; the development of new models for studying cutaneous penetration; the elucidation of the mechanisms of nonallergic inflammatory reactions (primary irritation) and of the accommodation phenomenon; the development of more sensitive models for predicting adverse responses to marginal irritants; the utilization of modern skills of immunobiology and immunochemistry to elucidate mechanisms of allergic responses; the launching of epidemiologic studies to determine the long term effects of PCBs and associated compounds such as dioxins; and the expansion of research in the mechanisms of skin cancer in relation to susceptibility, genetic and metabolic considerations, ultraviolet light, and phototoxic agents.

Environment and the skin.

The skin is an important organ of defense adaptation and a portal of entry for xenobiotics. It is vulnerable to physical, chemical, and biologic agents and capable of expressing responses to these agents in a variety of pathologic patterns. These patterns are characterized by morphologic and functional features which are elicited by careful examination and test procedures. Cutaneous cancer may result from exposure to nonionizing as well as ionizing radiation, to specific identifiable chemical hazards, and may be enhanced by trauma. Cutaneous hazards of chemical sources are largely found in the workplace and among consumer products, including drugs and toilet goods. Environmental skin diseases and injuries are preventable. Prior to use assessment for safety and for possible risks from exposure to an agent, product, or process is of primary importance in the prevention and control of environmental skin disease and injury.

Allergic contact sensitization potential of hydroxycitronellal in humans.

Hydroxycitronellal, an important ingredient in fragrances, was studied for its sensitizing potential in human skin. Fifteen human maximization tests were conducted with hydroxycitronellal obtained from four different sources at induction concentrations from 5 to 12%. No reactions were induced at 5% in two separate panels while 10% sensitized 2/25 panelists in one test but none in a second. Induction at 12% produced sensitization in 8 of 11 tests. Impurities do not appear to be a sensitizing factor. There is some evidence that the l-stereoisomer is a less potent sensitizer than the d-stereoisomer. In an initial modified human repeat-insult patch-test two positive reactions to challenge were observed among 197 panelists, one at a concentration of 5% and the other at 7.5%. When 100 of the non-reacting panelists were re-exposed in the same way, allergic sensitization reactions appeared during the induction period with concentrations as low as 2.5%. When 28 sensitized panelists were exposed to 1% concentrations in a simulated use test, there were three reactors. A no-effect level for sensitization has not been determined although the lowest concentrations tested were in the product usage range.

Chloracne, "the hallmark of dioxin intoxication".

Clinical experiences and laboratory studies are described involving a population of workers who were exposed in a plant making 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), including a trichlorophenol runaway reaction. Workers were followed for a period of four years, and 30 years later a mortality analysis was done on those exposed to runaway reaction material to determine possible increased risks for causes of death. Subsequently, a morbidity study on 436 employees involving three cohorts was carried out to determine the long-term health effects associated with the production of 2,4,5-T including 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The mortality and morbidity studies demonstrated that the standardized mortality ratio for all causes of death was 69, and for cancer at all sites and cardiovascular disease it was 100 and 68, respectively. The most significant observations emerging from the morbidity study were that 86% of the exposed persons developed chloracne at some time and that 52.7% still had chloracne on examination 20 to 30 years after the initial exposure. There appeared to be no evidence, on a long-term basis, of increased risks for cardiovascular disease, hepatic disease, renal disease, central and peripheral nerve problems, reproductive problems, or birth defects among the exposed and those who had chloracne among the exposed. Studies on the cell kinetics and pathogenesis of chloracne indicate that TCDD induces the modulation of undifferentiated sebaceous gland cells to keratinocytes. This action results in a disappearance of sebaceous glands and substitution of closed comedones and keratin cysts. Production workers have the highest frequency and severity of chloracne and systemic effects.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative studies of the sensitization potential of morpholine, 2-mercaptobenzothiazole and 2 of their derivatives in guinea pigs.

The aim of this study was to determine the sensitization potential of morpholine (M), 4,4'-dithiodimorpholine (DTDM), morpholinyl-mercaptobenzothiazole (MMBT) and 2-mercaptobenzothiazole (MBT) in guinea pigs. 5% and 10% DTDM, MMBT and MBT produced irritation reactions. M up to 10% failed to irritate. Sensitization tests showed that all the guinea pigs treated with DTDM and MMBT were sensitized. Cross-sensitization tests showed that 60% of the DTDM-sensitized animals reacted to challenge with MMBT; 30% of the animals sensitized to DTDM reacted to challenge with M; 80% of the MMBT-sensitized animals reacted to challenge with MBT and 10% to challenge with M; 42% of the MBT-sensitized animals reacted to MMBT. The rank order of sensitization potential in guinea pigs observed from this study is DTDM, MMBT and then MBT. It appears that the disulfide bond, sulfur linkage and the sulfhydryl group may each play a role in the sensitizing capacity of these compounds.

The mortality experience of workers exposed to tetrachlorodibenzodioxin in a trichlorophenol process accident.

A standardized mortality analysis was conducted on workers exposed to tetrachlorodibenzodioxin in a trichlorophenol process accident at the Monsanto Company plant in Nitro, West Virginia. One hundred and twenty-one workers who developed chloracne resulting from this accident on March 8, 1949, were selected for study. Follow-up of this group was 100% complete. The standardized mortality ratio for all causes of death was shown to be 0.69, with 32 deaths observed and 46.41 expected. For the categories of malignant neoplasms and circulatory diseases, the standardized mortality ratios were 1.00 and 0.68, respectively. Because of the small size of the cohort and the relatively small number of deaths observed, the results of this study cannot be considered conclusive. However, it is important that no apparent excess in total mortality or in deaths from malignant neoplasms or diseases of the circulatory system was observed in a group of workers with a high peak exposure to tetrachlorodibenzodioxin who were followed over a period of nearly 30 years. The results of this study will be incorporated with those of a larger study which will include plant workers exposed in the course of 2,4,5-trichlorophenoxyacetic acid production during the period 1948 to 1969.

Human health effects of 2,4,5-T and its toxic contaminants.

A clinical epidemiologic study was conducted to determine the long-term health effects of workplace exposure to the process of manufacturing the herbicide (2,4,5-trichlorophenoxy)acetic acid including contaminants such as 2,3,7,8-tetrachlorodibenzo-rho-dioxin. The population consisted of two cohorts: 204 clearly exposed and 163 not exposed. Among the exposed, clinical evidence of chloracne persisted in 55.7%. None of the not exposed experienced chloracne development. An association was found between the persistence of chloracne and the presence and severity of actinic elastosis of the skin. There is an association between exposure and the history of gastrointestinal tract ulcer. Pulmonary function values among those who were exposed and who currently smoked were lower than those who were not exposed and who currently smoked. The data assembled in the study indicate no evidence of increased risk for cardiovascular disease, hepatic disease, renal damage, or central or peripheral nervous system problems.

Mechanism of cinnamaldehyde sensitization.

The skin sensitization of cinnamaldehyde is probably initiated by the reaction of cinnamaldehyde with epsilon-amino groups on protein side chains. Alpha-Substituted cinnamaldehydes, which are known not to be skin sensitizers, react very slowly or not at all with amines in comparison with cinnamaldehyde.