High Cancer Incidence Area Research Articles

Internal biomarkers and external estimation of exposure to polycyclic aromatic hydrocarbons and their relationships with cancer mortality in a high cancer incidence area

This study aimed to evaluate internal biomarkers and external estimation of exposure to polycyclic aromatic hydrocarbons (PAH) in a high cancer mortality area in southeast China and identify which of these showed a stronger association of PAH with cancer mortality. A retrospective death survey was conducted to determine the mortality rate of cancer. Cumulative and aggregate external exposures to PAHs of local residents were estimated by field sampling. Three regions in southwest China with gradient PAH exposure levels from high to low (H, M, and L) were selected in this study. Research participants were selected from these three regions using a statistical sampling method. To determine the internal exposure, urinary OH-PAHs were measured using the first morning urine samples. From the retrospective death survey, the highest age-standardized lung cancer mortality rate occurred in Region H (78 per 100,000 person-years), followed by that in Regions M (33 per 100,000 person-years) and L (15 per 100,000 person-years), and the rate was nearly four times China's national mortality rate (20 per 100,000 person-years). Residents estimated daily aggregate exposure doses per unit body weight to carcinogenic benzo(a)pyrene equivalent concentration were 159 ± 14 ng-kg−1-day−1, 7.41 ± 2.76 ng-kg−1-day−1, and 6.13 ± 2.89 ng-kg−1-day−1 in Region H, M, and L, respectively. The participants in Region M had the greatest urinary OH-PAH concentration (9.10 ± 4.92 μg-g−1 crt), followed by Region H (8.01 ± 4.22 μg-g−1 crt) and L (7.12 ± 3.10 μg-g−1 crt). The spatial difference in the total OH-PAHs was not statistically significant. Aggregate and cumulative exposure to 16 PAHs from external routes were found, and external exposure had a stringer relationship with lung cancer mortality than internal exposure.

Health risk from dietary exposure to polycyclic aromatic hydrocarbons (PAHs) in a typical high cancer incidence area in southwest China

This study was designed to test whether the dietary intake of polycyclic aromatic hydrocarbons (PAHs) is a potential exposure source relating to the high cancer incidence area in southwest China. Duplicate plate method was used to collect food samples in rural and urban sites in the region. Questionnaire surveys were conducted among 300 local residents to obtain their dietary habits and 50 subjects were chosen to collect the samples. The 16 priority PAHs (PAH16) in composite food samples for each individual subject were measured, and non-carcinogenic and carcinogenic risks were analyzed based on the results of Monte Carlo method. The average concentration of the PAH16 in food samples was 12.04 ± 8.52 ng g−1. The life time average daily benzo(a)pyrene equivalent (BaPeq) exposure dose was 6.07 × 10−6 mg kg−1 day−1. Although non-carcinogenic risk was found to be within a controllable range, the average incremental lifetime cancer risk (ILCR) was 3.7 × 10−5 for rural subjects and 6.1 × 10−5 for urban subjects, which is comparable with other regions in China. The serious risk level of 10−4 was exceeded by 10.7% of urban residents and 2.1% of rural residents. This study implies that dietary exposure to PAHs is a potential exposure source to the high cancer in the region, and further cancer risk control strategies need to be formulated.

Disparity of nitrate and nitrite in vivo in cancer villages as compared to other areas in Huai River Basin, China

Saliva and Urine samples were collected for the study on how nitrate and nitrite concentration in human body may be related to the corresponding health risk in a high cancer incidence area. The study area includes three known cancer villages in Huai River basin, China. The results of analyzing collected sample show that there are higher levels of nitrate and nitrite concentration in human saliva and urine sample collected in the study area as compared to those collected in other areas. In addition, levels of nitrate and nitrite concentration in saliva and urine sample change significantly with the ages of sampled population. NO3-concentrations in saliva and urine sample are the most outstanding among the middle-aged and elderly populations. It means that the middle-aged and elderly populations have relatively high vivo nitrate reductive transformation rates and they also have higher N-nitroso compounds synthesis risks in the studied cancer villages.

N-nitrodimethlyamine in natural and drinking water of high cancer incidence regions of Guangdong, China

The Guangdong province of China contains the most clearly described high-incidence of hepatocellular carcinoma (HCC) and nasopharyngeal carcinoma (NPC) areas in the world. The geographical heterogeneity of cancer incidence in the region suggests that many carcinogenic risk factors might be present in the regional geochemical environment. This paper presents the concentrations of a wide range of known carcinogens in two high cancer incidence areas in Guangdong and compared them to a low cancer incidence area in the same province. N-Nitrosamines, NO3−, NO2−, and ammonium were detected in groundwater, surface water, and drinking-water. The concentrations of the 7 trace metal and metalloid elements As, Cd, Ni, Cu, Pb, Zn, and Hg were determined in surface soil samples and all water samples. The results show that, compared with the guidelines or limit values for drinking-water quality in the world, the high cancer incidence areas have hazardous high levels of N-nitrodimethlyamine (NDMA) in all kinds of water. Oppositely, the low cancer incidence area has a safe low level of NDMA in water bodies. The levels of NO3−, NO2−, and ammonium in water have the same character, although they have different expression between the two high-risk areas. The distribution of the 7 tested trace elements in surface soil has no significant correlation with cancer incidence. On the other hand, high concentrations of carcinogenic N-Nitrosamines in drinking-water and natural water bodies were identified for the first time in the high NPC and HCC incidence area.

Primary investigation of quartz as a possible carcinogen in coals of Xuanwei and Fuyuan, high lung cancer incidence area in China

Xuanwei and Fuyuan, located in southwest China, are two counties with extremely high lung cancer incidence. Pollution, relative to coal combustion, especially serious air pollution generated by burning smoky coals in unvented households was the most predominant cause. Quartz as a possible inorganic carcinogen in all typical coals (18 sites in Xuanwei and 14 sites in Fuyuan) were sampled and examined to determine the relationships between quartz content and lung cancer incidence. Scanning electron microscope-energy dispersive X-ray apparatus and X-ray diffractometer were employed for quartz analysis. It showed that it coincided with studies reported before in Xuanwei. Coal samples from high cancer incidence areas were all examined with high content of quartz, while coal samples from low cancer incidence areas with no content of quartz. However, data in Fuyuan received reverse results; many samples from low lung cancer incidence areas were found with quartz, but some samples from high lung cancer incidence areas were not found at the same detection limits. It indicated that quartz content in local coals has no significant relationship to lung cancer. This study added basic data and should be helpful to the future study on the etiology of lung cancer.