Population profile and residential environment of an urban poor community in Dhaka, Bangladesh.

OBJECTIVES: A population survey was conducted in an urban shantytown in Bangladesh, as a baseline study of future epidemiological studies. This paper aims to describe the findings of the study, including the population profile and residential environment of the urban poor. METHODS: We conducted a complete count household survey in an urban poor community in Dhaka. Using a brief structured questionnaire in Bengali language, trained interviewers visited each household and asked questions such as: duration of residence; ownership of house, toilet and kitchen; water supply; number of family members; age, sex, education, occupation, tobacco use, and history of diseases of each family member. RESULTS: We found that there were 8604 households and 34,170 people in the community. Average number of household members was 4.0. Most people had access to safe water, but only 16% lived in the house with a toilet. Based on the proxy indicators of household wealth levels, we identified that about 39% were relatively well-off, while the rest were very poor. Tobacco use was prevalent in men regardless of age and in women aged over 35 years. Prevalence of self-reported hypertension and diabetes was slightly higher in women than in men, although over 70% of the respondents didn't know if they had such diseases. Incidences of diarrhea in the last one month were relatively low. CONCLUSIONS: The study showed population profile and sanitation environment in an urban poor community by a complete count survey. We expect the study to serve as a baseline for future epidemiological studies.

Differences in urinary arsenic metabolites between diabetic and non-diabetic subjects in Bangladesh.

Ingestion of inorganic arsenic (iAs) is considered to be related to the development of diabetes mellitus. In order to clarify the possible differences in the metabolism in diabetics, we measured urinary iAs metabolites in diabetic cases and non-diabetic control subjects in Faridpur, an arsenic-contaminated area in Bangladesh. Physician-diagnosed type 2 diabetic cases (140 persons) and non-diabetic controls (180 persons) were recruited. Drinking water and spot urine samples were collected. Mean concentrations of total arsenic in drinking water did not differ between cases (85.1 µg/L) and controls (85.8 µg/L). The percentage of urinary iAs (iAs%) was significantly lower in cases (8.6%) than in controls (10.4%), while that of dimethylarsinic acid (DMA%) was higher in cases (82.6%) than in controls (79.9%). This may have been due to the higher secondary methylation index (SMI) in the former (11.6) rather than the latter (10.0). Adjusting for matching factors (sex and unions), and the additional other covariates (age and water arsenic) significantly attenuated the differences in iAs%, SMI, and DMA%, respectively, though the difference in monomethylarsonic acid% was newly significant in the latter adjustment. Our study did not suggest any significant differences in urinary arsenic metabolites between diabetic and non-diabetic subjects.

Enhanced carcinogenicity by coexposure to arsenic and iron and a novel remediation system for the elements in well drinking water.

Various carcinomas including skin cancer are explosively increasing in arsenicosis patients who drink arsenic-polluted well water, especially in Bangladesh. Although well drinking water in the cancer-prone areas contains various elements, very little is known about the effects of elements except arsenic on carcinogenicity. In order to clarify the carcinogenic effects of coexposure to arsenic and iron, anchorage-independent growth and invasion in human untransformed HaCaT and transformed A431 keratinocytes were examined. Since the mean ratio of arsenic and iron in well water was 1:10 in cancer-prone areas of Bangladesh, effects of 1 µM arsenic and 10 µM iron were investigated. Iron synergistically promoted arsenic-mediated anchorage-independent growth in untransformed and transformed keratinocytes. Iron additionally increased invasion in both types of keratinocytes. Activities of c-SRC and ERK that regulate anchorage-independent growth and invasion were synergistically enhanced in both types of keratinocytes. Our results suggest that iron promotes arsenic-mediated transformation of untransformed keratinocytes and progression of transformed keratinocytes. We then developed a low-cost and high-performance adsorbent composed of a hydrotalcite-like compound for arsenic and iron. The adsorbent rapidly reduced concentrations of both elements from well drinking water in cancer-prone areas of Bangladesh to levels less than those in WHO health-based guidelines for drinking water. Thus, we not only demonstrated for the first time increased carcinogenicity by coexposure to arsenic and iron but also proposed a novel remediation system for well drinking water.

Barium inhibits arsenic-mediated apoptotic cell death in human squamous cell carcinoma cells.

Our fieldwork showed more than 1 µM (145.1 µg/L) barium in about 3 µM (210.7 µg/L) arsenic-polluted drinking well water (n = 72) in cancer-prone areas in Bangladesh, while the mean concentrations of nine other elements in the water were less than 3 µg/L. The types of cancer include squamous cell carcinomas (SCC). We hypothesized that barium modulates arsenic-mediated biological effects, and we examined the effect of barium (1 µM) on arsenic (3 µM)-mediated apoptotic cell death of human HSC-5 and A431 SCC cells in vitro. Arsenic promoted SCC apoptosis with increased reactive oxygen species (ROS) production and JNK1/2 and caspase-3 activation (apoptotic pathway). In contrast, arsenic also inhibited SCC apoptosis with increased NF-κB activity and X-linked inhibitor of apoptosis protein (XIAP) expression level and decreased JNK activity (antiapoptotic pathway). These results suggest that arsenic bidirectionally promotes apoptotic and antiapoptotic pathways in SCC cells. Interestingly, barium in the presence of arsenic increased NF-κB activity and XIAP expression and decreased JNK activity without affecting ROS production, resulting in the inhibition of the arsenic-mediated apoptotic pathway. Since the anticancer effect of arsenic is mainly dependent on cancer apoptosis, barium-mediated inhibition of arsenic-induced apoptosis may promote progression of SCC in patients in Bangladesh who keep drinking barium and arsenic-polluted water after the development of cancer. Thus, we newly showed that barium in the presence of arsenic might inhibit arsenic-mediated cancer apoptosis with the modulation of the balance between arsenic-mediated promotive and suppressive apoptotic pathways.

Incidence of young onset insulin-requiring diabetes mellitus among 18- to 30-year-olds in Dhaka, Bangladesh (1994-2003).

Little information is available regarding the epidemiology of young onset insulin-requiring diabetes mellitus (IRDM). We described the incidence of young onset IRDM and its trend in males and females of Dhaka, Bangladesh. Subsequently, factors related to possible sex difference were investigated. Young onset IRDM was defined as diabetic patients aged 18-30 years who required three months or more insulin treatment but presented no ketonuria. Between 1994 to 2003, 1804 cases were registered. Incidence rates were calculated with denominators based on the population census 2001. The overall annual incidence of young onset IRDM for the period 1994-2003 was 8.5 per 100,000 persons (95% CI: 7.2-7.9), and the corresponding value for females (10.9 per 100,000 persons, 95% CI: 9.2-12.1) was higher than that in males (6.7 per 100,000 persons, 95% CI 5.6-7.9). The incidence rate significantly increased in females during the investigated period, but not in males (p for sex interaction < 0.01). There was a significantly higher increment of female cases with a body mass index > or = 25.0 kg/m2 (overweight/obesity) (19 percentage point) compared to that of males (3 percentage point) between 1994-1998 and 1999-2003 (p for sex interaction < 0.01). The incidence of young onset IRDM is increasing in the Dhaka City population among females, which is attributed to the increase in overweight/obese female cases.