Cancer and non-cancer mortality among Inhabitants in the High Background Radiation Area of Yangjiang, China (1979–1998)

Abstract

The present study aimed to evaluate the effects of high background radiation (HBR) on mortality. A cohort of 31,604 men and women aged 30-74 y living in the study area in Guangdong Province, China, was followed during the period 1979-1998. The information on deaths and migrations of cohort members was collected by visiting study areas every 3-4 y. Cumulative external radiation dose, lagged by 2 y for leukemia and 10 y for cancer excluding leukemia, was estimated for each individual based on hamlet-specific indoor and outdoor doses, and gender- and age-specific house occupancy factors. The follow-up study accumulated 736,942 person-years at risk and ascertained 6,005 deaths, including 956 cancer deaths and 4,525 non-cancer disease deaths. Mean cumulative radiation doses from natural radiation in the HBR and control area residents were 84.8 mGy and 21.6 mGy, respectively. Mortality due to leukemia (15 deaths) or cancer excluding leukemia (941 deaths) was not related to cumulative radiation dose. The excess relative risk (ERR) Gy of cancer excluding leukemia was estimated to be -1.01 (95% CI: -2.53, 0.95). In site-specific analysis, liver-cancer mortality was inversely related to the cumulative dose (p=0.002). Note, however, that liver cancer is well known for its difficulty in accurate diagnosis. The ERR Gy of cancer excluding leukemia and liver cancer was 0.19 (95% CI: -1.87, 3.04). Non-cancer disease mortality was not related to cumulative radiation dose either. The cumulative HBR dose was not related to the mortality due to cancer or all non-cancer diseases among residents in Yangjiang HBR areas.

A pilot study for dose evaluation in high-level natural radiation areas of Yangjiang, China

“…High background radiation areas of Yangjiang are made by deposit of monazite sand supplied from nearby mountains [4]. Most of residents have lived for six or more generations [4,10]. The present study was conducted in four villages, three in Yangdong county and one in Yangxi county.…”

“…A China-Japan cooperative study was organized and radiological and epidemiological studies were carried out [2,[5][6][7][8][9][10]. These studies did not find any statistically significant excess mortality due to cancer or non-cancer diseases [8,9].…”

Biological Effectiveness of Ionizing Radiation: Acute vs. Protracted Exposures

“…Conscious or subconscious dose-dependent behavioral changes have probably contributed to the dose-effect correlations found in epidemiological studies: one additional X-ray, endoscopy or blood count can lead to a cancer diagnosis thus influencing statistics. The same mechanism can cause in future an increase in the registered cancer incidence in the high natural background radiation areas (Guarapari, Brazil; Kerala, India; Ramsar, Iran; Yangjiang, China), where no cancer increase has been detected so far [2,[45][46][47][48]; although singular reports on enhanced cancer risk in such areas have already appeared [45,49].…”

Radiation survey on Fukushima Medical University premises about four years after the Fukushima nuclear disaster

“…The high air -kerma rates in these areas are attributed to the presence of naturally occurring thorium -rich soil, which is distributed in along the coast in Kerala 45) and is used as in building materials in Yangjiang 46) . Epidemiological surveys on the health effects due to external exposure in these areas indicated no statistically significant increase in mortality due to cancer or non -cancer diseases 47,48) . Thus, except for health effects resulting from initial exposure shortly after the nuclear disaster, no additional health effects due to chronic exposure to radiation from the deposited artificial radionuclides are expected.…”