ISSN:1059-0501    

DOI:10.1080/10590500009373517

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Wildlife populations are adversely affected in polluted environments. Nevertheless, a cause‐and‐effect relationship between excessive exposure to chlorinated hydrocarbons and induction of pathologic disorders in animals, is difficult to demonstrate without verification from experiments following the rationale of Koch's postulates. Deleterious effects of chlorinated chemicals such as DDT on songbird reproduction, as demonstrated by the clutch size of eggs in a nest, however, is an example, where exposure and causation are apparent. With amelioration of DDT pollution, clutch size increases, and the cause‐and‐effect relationship is established. Similar examples of exposure to DDT and PCBs inducing reproductive disorders and endocrine disruption among marine mammals have been documented in industrialized nations of northern Europe and in the upper latitudes of the Northern Hemisphere. Population declines in ringed, grey and harbor seals are apparently due to a rapid decrease in their rates of reproduction1. These latter observations are best interpreted in light of experiments conducted by Reijnders2. Reijnders exposed harbor seals to relatively high dietary levels of PCBs and induced PCB‐blood‐lipids among seals to an average of 25 mg/kg compared to 10 mg/kg among controls. The treated seals had a significantly reduced reproductive rate. A relationship between increased PCB‐blood‐levelsin vivoand the decrease in reproductive rates in this experiment is highly instructive for interpreting the decline of fertility in seal populations in polluted Baltic Sea waters. These linked observations are dependent upon demonstration of pathologic mechanisms associated with occlusion and stenosis of the uterine lumen among affected females in seal populations.

ISSN:1059-0501    

DOI:10.1080/10590500009373518

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Several ecological studies have suggested a link between domestic radon concentration and risk of leukemia at all ages. Children with acute lymphoblastic leukemia (ALL) aged 2–14 years were selected from the Hematology‐Oncology Clinic, Children's Hospital, Ain Shams University, Cairo. Full clinical history, complete blood picture, bone marrow aspiration, and radiographic examinations were taken. Due to the sequential study design, indoor radon measurements could only be done for 10% of the 500 ALL patients initially contacted, while 110 controls have agreed to participate in this study. Radon detectors were placed in homes of subjects resided in Cairo since their birth. Radon concentrations were measured within the period from September 1996 to August 1998 by passive alpha‐track radon detectors. Mean indoor radon concentration was higher for case subjects than for control subjects (p < 0.001). The mean alpha dose for case subjects (3.75 mSv.y‐1) was higher than the natural radiation dose value. For categories less than 40, 40–60, 60–90, and 90 or more Bqm‐3of radon exposure, odds ratios (ORs) based on unmatched case‐control analysis were 1.00, 4.64(95% confidence interval (CI) 1.2–18), 7.42(95% CI 2–27.3), and 5.42(95% CI 1.3–21.1) respectively. There was an association between ALL and radon exposure in this study. These data must be regarded as preliminary and further more extensive studies should be done to determine whether the observed association is causal.

ISSN:1059-0501    

DOI:10.1080/10590500009373519

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

ISSN:1059-0501    

DOI:10.1080/10590500009373516

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor