Epidemiological data

A comprehensive study of the tolerance of laboratory animals to vapors of 2-nitropropane was reported in 1952 (100). In a study pubHshed in 1979, rabbits and rats survived exposure to nitromethane for six months at 750 and 100 ppm, respectively, with no unexpected findings (101). Similarly, no compound-related effects were found for rabbits exposed to 2-nitropropane at 200 ppm or for rabbits or rats exposed at 27 ppm. Liver damage was extensive in male rats exposed at 207 ppm for six months, and hepatocellular carcinomas were observed. Subsequendy, the International Agency for Research on Cancer (lARC) found that there is "sufficient evidence" to conclude that 2-nitropropane causes cancer in rats but that epidemiologic data are inadequate to reinforce the conclusion in humans (102). The National Toxicology Program also concluded that it "may reasonably be anticipated to be a carcinogen" (103). 

The replacement of asbestos fibers by other fibrous materials has raised similar health issues in relation to substitute materials. However, since lung cancer has a latency period of approximately 25 years, and since the fiber exposure levels in contemporary industries is far lower than those which prevailed half a century ago, the epidemiological data on most substitutes is insufficient. A possible exception is slag fibers for which several studies on worker populations are available over extended periods (44) some results show a substantial increase in lung cancer occurrence. Consequentiy, the toxicity of asbestos substitute fibers remains a subject of active investigation. 

Benzyl chloride also induced in vitro cellular transformation in Syrian hamster embryo cultures and DNA alkylation in several organs of the male mouse following iv adrninistration. In summary, lARC states there is limited evidence that benzyl chloride is carcinogenic in experimental animals epidemiological data was inadequate to evaluate carcinogenicity to humans (67). 

In the 1970s questions were raised about certain immunological complications as a consequence of male sterilisation or vasectomy. Clinical epidemiological data do not appear to indicate that this actually occurs in clinical practice. No significant long-term side effects of male sterilisation have been demonstrated. 

Discuss the problem caused by cigarette smoking in the evaluation of epidemiological data on the effect of air pollution on respiratory disease. 

Epidemiologic data come from many different sources. Acquiring reliable, accurate, and complete data describing occupational health problems is a key concern of the epidemiologist. A primary and continuing problem is the ascertainment of occupational disease. Ascertainment is the identification of diseases that are. in this case, of occupational origin. 

Lack of epidemiological data on humans of the same sex, age, education, etc. 

Benchmark Dose Model—A statistical dose-response model applied to either experimental toxicological or epidemiological data to calculate a BMD. 

Epidemiological data on the protective effects of plant foods provides convincing evidence that a high consumption of brassica vegetables is inversely... 

Epidemiological data on carotenoids and cerebral infarcts or strokes indicate a protective effect of P-carotene and lycopene. Indeed, the Basel prospective study, the Kuopio Ischaemic Heart Disease Risk Factor study, and the Physicians Health Study " have shown an inverse correlation between carotenoid plasma level and risk of stroke. In the same way, Hirvonen et al. demonstrated, in findings from the ATBC cancer prevention stndy, an inverse association between P-carotene dietary intake and stroke. However, clinical data on carotenoids and stroke are nonexistent and they are needed to confirm this possible protective effect of carotenoids on stroke. 

Epidemiologic data show that 10% to 30% of patients with schizophrenia develop their first psychotic symptoms prior to their eighteenth birthday. Onset between puberty and age of 18 is sometimes classified as early-onset schizophrenia (EOS) or intermediate onset schizophrenia, and those presenting with symptoms before puberty are classified as very early-onset... 

Dry eye is a frequent cause of eye irritation. A lack of a single diagnostic test for the condition limits the available epidemiologic data. One study estimated the prevalence of dry eye in the United States population age 65 and older at 14.6%, which is approximately 4.3 million Americans.29... 

Epidemiological and Human Dosimetry Studies. Epidemiological studies of radiation dose typically involve estimates of exposure that are based on whole-body measurements of internally-deposited americium. A need remains for epidemiological data that can provide quantitative human dose-response information while supplying additional information on the health effects of exposure to ionizing radiation and americium in particular, for cases of known internal exposure. 

CEDR. 2000. Comprehensive epidemiological data resource, http //cedr.lbl.edu. December 12, 2000. 

The lack of corroborative case reports, epidemiological data, or animal data (see next paragraph) makes the association between dermal exposure to mineral oil hydraulic fluids and peripheral neuropathy uncertain. Nonetheless, the presence of organophosphate esters, some of which are demonstrated neurotoxic agents, in most mineral oil hydraulic fluids (they often are added as anti-wear agents) suggests that they may play a causative role if such an association exists. 

However, results obtained by Koo et al. (1991) indicate that low to moderate lead exposure (average lifetime PbB level range of 4.9-23.6 pg/dL, geometric mean of 9.8 pg/dL, n=105) in young children with adequate nutritional status, particularly with respect to calcium, phosphorus, and vitamin D, has no effect on vitamin D metabolism, calcium and phosphorus homeostasis, or bone mineral content. The authors attribute the difference in results from those other studies to the fact that the children in their study had lower PbB levels (only 5 children had PbB levels >60 pg/dL and all 105 children had average lifetime PbB levels <45 pg/dL at the time of assessment) and had adequate dietary intakes of calcium, phosphorus, and vitamin D. They concluded that the effects of lead on vitamin D metabolism observed in previous studies may, therefore, only be apparent in children with chronic nutritional deficiency and chronically elevated PbB levels. Similar conclusions were reached by IPCS (1995) after review of the epidemiological data. 

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