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A large number of fluorosis and arseniasis cases appeared in a mountainous area in northwest China. The residents relied on local inferior coal ("bone coal") of high fluorine and arsenic content for domestic heating and cooking. For deep-inside information about this rare case of co-endemia of fluorosis and arseniasis in the population in this special exposure scenario, a field investigation in one of the hyperendemic townships was conducted. The resident population registered (n = 27,713) was enrolled in the investigation. All cases were diagnosed and assigned to three symptom severity groups, that is severe, medium, and mild according to Chinese National Standard Criteria GB 16396-96 and to the technical guideline WS/T208-01 or WS/T211-01 issued by the Chinese Ministry of Health. Gender difference was analyzed by standardized incidence ratio. Age trend and severity trend were tested by χ(2) analysis. Fluorosis was diagnosed in 56.7% of the residents. Over 95% of the diagnosed arseniasis cases were simultaneously diagnosed with fluorosis symptoms. Combined fluorosis-arseniasis represented 11.9% of the total fluorosis cases and 6.7% of the local population. No gender-related differences in the prevalence of skeletal, dental, or dermal symptoms inside all severity groups were detected. Symptom severity increased with age. The high frequency of superposition of arseniasis with fluorosis might be due to the fact that the local resident population has been exposed to very high levels of fluorine and arsenic via the same exposure route.

Background: A few villages in Southwest Guizhou, China represented a unique case of arseniasis due to indoor combustion of high arsenic-content coal. The present study is aimed to analyze the contribution of possible factors or of their combination to excess prevalence of arseniasis in the exposed population., Methods: An epidemiological investigation was conducted in all the members of three large ethnic, patrilineal clans in one of the hyperendemic villages (702 residents in 178 families, including 408 Han and 294 Hmong) where farmers of different ethnic origin have been living together in the same village for generations. A multilevel model logistic regression analysis was performed., Results: The arseniasis prevalence was found to associate with the duration of As indoor exposure (years of high As coal burning and of poorly ventilated traditional stove using) and is largely dependent on the subject's ethnicity and clan consanguinity, too. The prevalence of arseniasis in ethnic Han residents was significantly higher than that in their Hmong neighbors (35.0 vs 4.8% OR = 15.18, 95% CI = 3.45-67.35). Notable variances of arseniasis prevalence were observed not only between the ethnic Han clans (G1, G3, and B) and Hmong clan P, but also between different lineages (G1 and G2) inside the ethnic Han clan. Smokers suffered more frequently from arseniasis than non-smokers (47.3 vs 15.7% OR = 5.42, 95% CI = 2.25-12.93)., Conclusions: Arseniasis prevalence in this unique exposure case was impacted by an array of multiple factors. Besides a long-term indoor exposure to As, the ethnicity or the clan consanguinity of exposed subjects may play an important role, too.

More than 2,000 arsenic-related skin lesions (as at 2002) in a few villages of China's Southwest Guizhou Autonomous Prefecture represent a unique case of endemic arseniasis related with indoor combustion of high-arsenic coal. The skin lesion prevalence was significantly higher in ethnic Han villagers than in ethnic Hmong villagers. This study was focused on a possible involvement of XPD/ERCC2 G23591A and A35931C polymorphisms in risk modulation of skin lesions and in the body burden of As in this unique case of As exposure. G23591A and A35931C were genotyped by a PCR-based procedure. Total As contents in hair and urine samples as well as environmental samples of the homes of the two ethnic clans were analysed. A significant higher presentation of A/A35931 (homozygous wild) genotype in both clans was found in skin lesion patients, compared with their asymptomatic fellow villagers (67.1 vs. 46.3%, OR 2.36, 95% CI 1.35-4.14, P=0.002). Interestingly, the population frequencies of the A/A35931 genotype did not show significant differences between ethnic Han villagers and their Hmong neighbours (47.1 vs. 45.5%). Very low frequencies of homozygous and heterozygous variant genotypes of G23591A were recorded in the residents in target village. G/A23591 and A/A23591 were detected only in 3.2% (8/244) and 0.8% (2/244) of the villagers, respectively. The polymorphic status at the locus of A35931C might modulate the risk for arsenic-related skin lesions in the investigated groups.

Objective: Farmers in Southwest Guizhou Autonomous Prefecture, China, represent a unique case of arseniasis, which is related to indoor combustion of high arsenic-containing coal instead of to arsenic-contaminated drinking water. A significant difference in the prevalence of arseniasis was observed in two neighboring ethnic clans in one village. The question arose whether the ethnicity-dependent difference observed in this village was more widely spread throughout the whole township. An epidemiologic investigation was designed to explore arseniasis distribution and mortality among all four ethnic groups in a multiethnic township., Methods: The cohort of arseniasis patients, diagnosed and registered in the overall field survey of 1991 as well as all the asymptomatic residents of the township, were enrolled in the present investigation. Indirect standardization was used for calculating the age-adjusted standardized incidence ratio (SIR) of arseniasis, the standardized mortality ratio (SMR) of various death causes (including some cancers), and their corresponding intervals of 95% confidence in both genders and in each local ethnic group., Results: The descending rank of arseniasis SIRs among local ethnic groups was found as: Hui>Han>Bouyei>Hmong. The descending rank of SMRs of malignancies was displayed as: Han>Hui>Bouyei>Hmong in males and both genders together as well. Concerning deaths of non-malignant causes the rank was observed as: Hui>Han>Bouyei>Hmong in males. The arseniasis SIR for ethnic Hmong residents (both genders combined) was found to be significantly less profound than the overall level in the township. No death cases in diagnosed ethnic Hmong patients and no cases of death from malignant causes in asymptomatic Hmong residents were recorded. The significant increase of arseniasis prevalence was observed in all males, compared with the overall prevalence of all residents. However, a significantly lower prevalence was seen in all females., Conclusion: Significant ethnicity-dependent difference in arseniasis prevalence and mortality from all causes was found in a multiethnic rural township where farmers have been exposed to the indoor combustion of high arsenic coal for decades. The ethnic Hmong residents seemed to be the least susceptible to arseniasis among the four local ethnic groups.

Objective: This study was directed to ascertain the mortality of a group of arseniasis patients in an endemic rural township in Southwest China, where the residents were exposed for decades to indoor combustion of high arsenic coal., Methods: All the diagnosed arseniasis cases registered in 1991 were defined as the target population, which were assigned to three symptom subgroups by the severity of dermal lesions. The death cases were surveyed and checked. The follow-up period was 12.5 years. The standardized mortality ratio (SMR) of all death causes combined, all cancers combined, and the cancers at every site were analyzed. The age standardized mortality rates (ASMRs) were calculated in three subgroups using the procedure of standardization., Results: One hundred and six death cases were recorded. Liver cirrhosis, non-melanotic skin cancer, lung and liver cancer were the four most prevalent death causes and referred to 70.8% (75/106) of the total death cases. The mortality of all death causes combined was not higher than that of the whole of China in 2001 (SMR = 0.76, 95% CI 0.63-0.93). The crude mortality rate of non-melanotic skin cancer in males reached up to 128.66/10(5). SMRs of lung cancer and larynx cancer in males (SMRs 2.84 and 27.27, 95% CIs 1.51-4.86 and 5.61-79.62, respectively) significantly exceeded the levels for all male Chinese. ASMRs of all death causes combined, all cancers combined and non-melanotic skin cancer in males of the severe dermal symptoms subgroup were significantly higher than those in medium and/or mild dermal symptom subgroups., Conclusions: A significantly increased mortality due to lung cancer and non-melanotic skin cancer was confirmed, alike the situation in other arseniasis endemic areas in the world. No significant elevation of mortality due to liver cancer and bladder cancer was observed. Male arseniasis patients diagnosed with severe skin lesions face higher risks of malignancies and of non-melanotic skin cancer in particular in the following years.

A total of 2,402 cases of arsenic-related skin lesions (as of 2002) in a few villages of China's Southwest Guizhou Autonomous Prefecture represent a unique case of endemic arseniasis related with indoor combustion of high arsenic coal. A significant difference of skin lesion prevalence was observed between two clans of different ethnicities (Hmong and Han) in one of the hyperendemic villages in this prefecture. This study was focused on a possible involvement of GST T1 and M1 polymorphisms in risk modulation of skin lesions and in the body burden of As in this unique case of As exposure. GST T1 and M1 polymorphisms were genotyped by an allele-specific PCR-based procedure. Total As contents in hair and urine samples as well as environmental samples of the homes of the two ethnic clans were analyzed. No significant deviations in the population frequencies of GST T1 and M1 0/0 genotypes or their combination were recorded between diagnosed skin lesion patients and asymptomatic individuals in both clans. Significantly higher As contents in hair and urine were observed in GSTM1 0/0 carriers, not in GSTT1 0/0 carriers. After stratified by ethnicity and gender, a statistically significant association of the GSTM1 0/0 genotype and higher As content in hair was only confirmed in the subgroups of ethnic Han clan members and all male villagers, not in ethnic Hmong clan members or in females. GST T1 and M1 homozygous deletions were not associated with an increased susceptibility to skin lesions in long-term exposure to indoor combustion of high As coal. The polymorphic status at the locus of GSTM1 might modulate individual's body burden of total As in some Chinese ethnic groups.

N-acetyltransferase 1 (NAT1) modifies bladder cancer risk in European populations exposed to aromatic amines in cigarette smoke. The present study was performed to investigate a possible association between NAT1*10 and NAT1*14A genotypes and bladder cancer risk in benzidine-exposed Chinese workers. Based on the cytological gradings of exfoliated urothelial cells according to Papanicolaou, an exposed research cohort was stratified into subgroups. An allele-specific PCR-based procedure was used to detect the polymorphism in the polyadenylation signal at the locus NAT1 T(1088)A. A nested PCR-RFLP procedure was conducted to differentiate NAT1*14A (T(1088)A, C(1095)A, and G(560)A) from NAT1*10 (T(1088)A, C(1095)A). No significantly different frequencies of homozygous and heterozygous NAT1*10 alleles were found among the subgroups with (i) gradings according to Papanicolaou < or = II (18.3 and 40.2%, respectively), (ii) higher gradings according to Papanicolaou (> II; 28.0 and 34.1%, respectively), and (iii) with bladder cancer (26.3 and 34.2%, respectively). The present data show that NAT1*10 neither displayed an association with an elevated grading of urothelial cells nor a clear impact on the risk for bladder cancer in benzidine-exposed Chinese workers. Discrepancies with the findings in European populations could point to ethnic differences in the disposition of aromatic amines.

Male Wistar rats exposed to atmospheric n-hexane excreted in their urine substances which gave rise to absorption spectra like those of pyrroles after the reaction with Ehrlich's reagent. A simple spectrophotometric assay was developed to determine these "pyrrole-like substances" in urine. Their excretion kinetics were evaluated by exposing rats for 8 h to atmospheric n-hexane concentrations between 50 and 3000 ppm. The dose-response curve revealed saturation kinetics according to Michaelis-Menten, Vmax being 1.12 [delta E526.ml urine/8 h n-hexane exposure] and "Km", the atmospheric n-hexane concentration at Vmax/2, being 250 ppm. The excretion of pyrrole-like substances closely correlated with that of 2,5-hexanedione measured by Fedtke and Bolt (1987). Pyrrole-like substances were also found in the urine of a male volunteer. When exposing the person for 3 h to atmospheric n-hexane at a concentration of 146 ppm (equivalent to 55 ppm/8 h) the excreted amount was twice the background value. Due to the sensitivity of this assay it is possible to determine pyrrole-like substances in urine according to the present German MAK or US TLV conditions for n-hexane (50 ppm/8 h).