Epidemiologic observations

Chnical and epidemiological observations suggest that inhalant use in humans occurs along a continuum, with considerable variability in usage patterns among individuals as a function of age, gender, socioeconomic status, ethnicity, avahabihty and type of inhalant, and other clinical variables. As a general rule, it is expected that as inhalant consumption and frequency of intoxication increase, the incidence and severity of medical and psychosocial problems wiU increase. 

These take into account the systemic effects of lethal concentrations and doses (LC and LD50). However, when epidemiological observation has shown that effects for humans are different from those observed with experiments on animals, the observations on humans are the ones that will be taken into account. 

These remarks are not Intended as a deterrent against control measures, which are readily justified by the documented occurrence of acute ventilatory effects. It is suggested, however, that sufficient data do not exist to warrant extrapolation of existing epidemiological observations to chronic effect conclusions. Additional studies are recommended prior to such conclusions. 

Fluoride is well established as effective for the prophylaxis of dental caries and has been under investigation for the treatment of osteoporosis. Both therapeutic applications originated from epidemiologic observations that subjects living in areas with naturally fluoridated water (1-2 ppm) had less dental caries and fewer vertebral compression fractures than subjects living in nonfluoridated water areas. Fluoride is accumulated by bones and teeth, where it may stabilize the... 

In clinical trials, the preventive effect of 3-carotene supplementation on cancer or cardiovascular disease could not be demonstrated in a well-nourished population. This apparent ineffectiveness contrasts starkly with the promising results of numerous basic studies and epidemiological observations, which suggest that supplementation with this antioxidant is likely to have a protective effect. 

The incidence of esophageal cancer varies widely in different areas of the world (1). There is as much as 300-fold variation from areas of low incidence to that of the highest rates in places such as the southern Caspian littoral in Iran, the Transkei in South Africa and in some parts of China. These epidemiological observations provide opportunities to identify environmental factors and to test these real or potential factors in appropriate animal models (2) ... 

Harington JS. 1981. Fiber carcinogenesis Epidemiologic observations and the Stanton hypothesis. J Natl Cancer Inst 67 977-989. 

The withdrawal of phenacetin from analgesic mixtures in Western Europe and the United States, gave rise to question the nephrotoxic potency of the different kinds of products without phenacetin, available on the market [10]. The nephrotoxic potency of the newer analgesic mixtures could be demonstrated using different kinds of epidemiological observations [46]. 

Furtheron, a broad range of other clinical and epidemiological observations is in support with the previous results. For single analgesics, abuse is only poorly documented and the nephrotoxic potency of single analgesics can be considered as minimal. Even in patients with rheumatoid arthritis in which high... 

Knowledge regarding renal injury and the development of anti-neutrophil cytoplasmic antibody (ANCA) positivity associated with silica exposure is rudimentary being hmited to epidemiological observations. Moreover, information about the health significance of the occupational exposure to other silicon containing compounds apart from silica and crystalline sihcates is lacking. 

Effects of Excess Tissue Iron on Ascorbic Acid Metabolism. Epidemiological observations among the Bantu of South Africa showed an apparent association of clinical scurvy in adult males with hemosiderosis common to this group. Both plasma clearance of ascorbic acid and urinary excretion of ascorbic acid were altered in severe iron overload plasma clearance was increased and urinary excretion was decreased in siderotic subjects (40,41), The evidence was interpreted as a demonstration of enhanced oxidative catabolism of ascorbic acid in the presence of excess tissue iron. 

---