Epidemiologic studies case reports

There are no epidemiological or case reports of mirex-exposed individuals. The literature reviewed for the health effects of chlordecone in humans came from reports of one occupational cohort of workers exposed to chlordecone in a manufacturing plant. This exposure was classified as intermediate-to-chronic no precise duration or level of exposure to chlordecone could be quantified from these reports. A single route of exposure could not be established for this worker population poor hygiene in the plant made inhalation, oral, and dermal exposure routes likely to occur. The information on human exposure in this study is extremely limited because of the possible contamination with the precursor used to manufacture chlordecone, hexachloropentadiene. Therefore, information on human exposure to both mirex and chlordecone is limited. 

Evidence of the induction of cancer in humans obviously plays an important role in the identification of human carcinogens. Three types of epidemiological studies contribute to an assessment of carcinogenicity in humans cohort studies, case-control studies and correlation (or ecological) studies. Case reports of cancer in humans may also be reviewed. 

Based on the current hterature from experimental animal studies, case reports, case-confrol studies, and epidemiological studies, one can conclude that the studies show ... 

Acute poisoning of humans by freshwater cyanobacteria as occurs with paralytic shellfish poisoning, while reported, has never been confirmed. Humans are probably just as susceptible as pets, livestock, or wildlife but people naturally avoid contact with heavy waterblooms of cyanobacteria. In addition, there are no known vectors, like shellfish, to concentrate toxins from cyanobacteria into the human food chain. Susceptibility of humans to cyanobacteria toxins is supported mostly by indirect evidence. In many of these cases, however, if a more thorough epidemiological study had been possible these cases probably would have shown direct evidence for toxicity. 

Carotenoids and prostate cancer — Numerous epidemiological studies including prospective cohort and case-control studies have demonstrated the protective roles of lycopene, tomatoes, and tomato-derived products on prostate cancer risk other carotenoids showed no effects. " In two studies based on correlations between plasma levels or dietary intake of various carotenoids and prostate cancer risk, lycopene appeared inversely associated with prostate cancer but no association was reported for a-carotene, P-carotene, lutein, zeaxanthin, or p-cryptoxanthin. - Nevertheless, a protective role of all these carotenoids (provided by tomatoes, pumpkin, spinach, watermelon, and citrus fruits) against prostate cancer was recently reported by Jian et al. ... 

A number of epidemiologic studies support an association between high fat intake and the risk of prostate cancer. A strong correlation between national per capita fat consumption and national prostate cancer mortality has been reported, and prospective case-control studies suggest that a high-fat diet doubles the risk of prostate cancer. 

Human studies including case reports, epidemiological studies, and, in some cases, direct human studies (with volunteers). The advantages of these studies are that toxic effects are evaluated in humans and no interspecies extrapolation is... 

Spores may be transferred from soil and plants to the sea via rainwater, causing the prevalence in coastal waters of the same C. botulinum types as on the land. Such a correlation was observed in Great Britain, where the type B predominates both in soil and in bottom sediments. Similarly, 71% of fish and bottom-sediment samples collected in southern France were contaminated with type B, while C. botulinum type E was found only in 9.6% of samples (Each et al., 2002). However, it is commonly believed that non-proteolytic type E is characteristic for the marine environment. A distinguishing feature of type E strains is the ability to grow in low temperatures (about 3°C), which are typical for bottom layers of seas and oceans. Moreover, the bottom sediments provide anaerobic conditions for the outgrowth of Clostridium. Therefore, the marine environment promotes C. botulinum type E distribution. This has been further supported by the rate of fish and seafood contamination fish and seafood isolated in many countries are most frequently contaminated with C. botulinum type E (Dodds, 1993 a,b). Furthermore, epidemiological studies have shown that the majority of botulism cases linked to fish and seafood consumption reported between 1950 and 1996 in the U.S. were caused by C. botulinum type E (Centers for Disease Control and Prevention 1998). C. botulinum type F,... 

The toxic properties of the chemicals to be discussed have been learned from the many types of general and specialized animal tests discussed in Chapter 3. In many cases they have also been learned from epidemiological studies and case reports. Carcinogens, as we have already mentioned, are excluded until the next two chapters. 

Most of the data located concerning the health effects of heptachlor and heptachlor epoxide in humans come from case reports and occupational epidemiology studies of workers engaged either in the manufacture or application of pesticides. There is some information on people who have consumed heptachlor-contaminated food or dairy products, but no adverse health effects have been related to these exposures. The occupational studies involve exposures that are predominantly inhalation with contributions from dermal exposure, whereas all the animal studies were conducted using oral or intraperitoneal exposures. The occupational and case reports provide no quantitation of dose or duration of exposure, which makes it impossible to determine with any precision the effect levels for humans. There are no data that indicate that heptachlor or heptachlor epoxide are carcinogenic to humans. However, human studies are limited by the long latency period of carcinogenesis and by ascertainment and follow-up biases. 

Deseriptive data are available from reports of humans exposed to 1,4-diehlorobenzene by inhalation (and possibly dermal contact). It is important to note that the case studies discussed in this section should be interpreted with caution since they reflect incidents in which individuals have reportedly been exposed to 1,4-dichlorobenzene, and they assume that there has been no other exposure to potentially toxic or infectious agents. There is usually little or no verification of these assumptions. Case studies in general are not scientifically equivalent to carefiilly designed epidemiological studies or to adequately controlled and monitored laboratory experiments. Thus, the case studies described below should be considered only as providing supplementary evidence that 1,4-dichlorobenzene may cause the reported effects. 

Cardiovascular Effects. Two case studies were found that reported mild hypertension in humans from acute inhalation exposures to fuel oils. Mild hypertension was noted for 4 days in one of two individuals following a 1-hour exposure to JP-5 vapor while flying a small airplane (Porter 1990). Delayed mild hypertension was also noted in a man who was exposed to diesel fuel vapor for 10 days while driving a truck with a fuel injector leak (Reidenberg et al. 1964). The concentration of vapor was not reported in either study. Palpitations were noted in workers chronically exposed to jet fuel according to one epidemiological study (Knave et al. 1978). The limitations of this study are discussed in detail in Section 2.2.1.2 under Respiratory Effects. 

In one case study, anorexia was reported in a man who washed his hands with diesel fuel over several weeks (Crisp et al. 1979). Effects resulting from inhalation versus dermal exposure could not be distinguished in this case. An epidemiological study found a significant increase in neurasthenia (i.e., fatigue, depressed mood, lack of initiative, dizziness, and sleep disturbances) in workers who were chronically exposed to jet fuels by either inhalation, oral, and/or dermal exposure (Knave et al. 1978). Also, attention and sensorimotor speed were impaired in the exposed workers, but no effects were found on memory function or manual dexterity. Results of EEG tests suggest that the exposed workers may have instability in the thalamocortical system. The limitations of the study were discussed in detail in Section 2.2.1.2 under Respiratory Effects. 

---