Excess dietary iodine intake in long-term African refugees

OBJECTIVE: To assess the iodine status of long-term refugees dependent on international food aid and humanitarian assistance. DESIGN: A series of cross-sectional two-stage cluster or systematic random sample surveys which assessed urinary iodine excretion and the prevalence of visible goitre. Salt samples were also collected and tested for iodine content by titration. SETTING: Six refugee camps in East, North and Southern Africa. SUBJECTS: Male and female adolescents aged 10-19 years. MAIN RESULTS: The median urinary iodine concentration (UIC) ranged from 254 to 1200 microg l(-1) and in five of the camps exceeded the recommended maximum limit of 300 microg l(-1), indicating excessive iodine intake. Visible goitre was assessed in four surveys where it ranged from 0.0 to 7.1%. The camp with the highest UIC also had the highest prevalence of visible goitre. The iodine concentrations in 11 salt samples from three camps were measured by titration and six of these exceeded the production-level concentration of 20 to 40 ppm recommended by the World Health Organization (WHO), but were all less than 100 ppm. CONCLUSIONS: Excessive consumption of iodine is occurring in most of the surveyed populations. Urgent revision of the level of salt iodisation is required to meet current WHO recommendations. However, the full cause of excessive iodine excretion remains unknown and further investigation is required urgently to identify the cause, assess any health impact and identify remedial action.     

Remaining challenges in Tanzania's efforts to eliminate iodine deficiency

OBJECTIVE: To determine iodine levels in salt and iodine deficiency prevalence in school-aged children in 16 districts in Tanzania with previous severe iodine deficiency. DESIGN: A cross-sectional study in schoolchildren. Systematic probability sampling was used to select schools and subjects for goitre assessment and urinary iodine determination. SETTING: Sixteen districts randomly selected from the 27 categorised as severely iodine-deficient in Tanzania. SUBJECTS: The study population was primary-school children aged 6-18 years who were examined for goitre prevalence and urinary iodine concentration (UIC). Salt samples from schoolchildren's homes and from shops were tested for iodine content. RESULTS: The study revealed that 83.3% of households (n=21,160) in the surveyed districts used iodised salt. Also, 94% of sampled shops (n=397) sold iodised salt, with a median iodine level of 37.0 ppm (range 4.2-240 ppm). Median UIC in 2089 schoolchildren was 235.0 microg l(-1) and 9.3% had UIC values below 50 microg l(-1). The overall unweighted mean visible and total goitre prevalence was 6.7% and 24.3%, respectively (n=16,222). The age group 6-12 years had the lowest goitre prevalence (3.6% visible and 18.0% total goitre, n=7147). The total goitre prevalence had decreased significantly in all districts from an unweighted mean of 65.4% in the 1980s to 24.3% in 1999 (P<0.05). We believe this difference was also biologically significant.ConclusionThese findings indicate that iodine deficiency is largely eliminated in the 16 districts categorised as severely iodine-deficient in Tanzania, and that the iodine content of salt purchased from shops is highly variable.     

The iodine content of Norwegian foods and diets

OBJECTIVES: To examine dietary iodine sources and to estimate the dietary iodine intake of the Norwegian population. DESIGN: Food iodine analyses carried out in Norway during the last 10 years were compiled, and iodine intake calculated on the basis of food intake data from nation-wide dietary surveys among children and adults. The food intake of adults was measured by a self-administrated food-frequency questionnaire, which covered habitual diet during the past year. The food intake of children was measured by dietary record during four consecutive days. SETTING: Neither household nor industrial iodisation of salt is mandatory in Norway, but some brands of table salt have 5 microg of iodine added per gram of NaCl. In spite of this, the population has been considered iodine-replete for decades, i.e. having an iodine intake well above the Recommended Dietary Allowance of 150 microg day(-1). This assumption has not been substantiated by dietary surveys. SUBJECTS: The adults included 1374 females and 1298 males aged 16-79 years. The children included 185 girls and 206 boys aged 4 years, 411 girls and 404 boys aged 9 years, and 517 girls and 492 boys aged 13 years. RESULTS: The calculated iodine intake was in the range of 100-250 microg day(-1) in the majority of the adult population. The mean iodine intake was 136 microg day(-1) (170 microg I/10 MJ) among women and 176 microg day(-1) (161 microg I/10 MJ) among men. For children the iodine intake was in the range of 100-120 microg day(-1). Milk and dairy products contributed approximately 55% and 70% of the dietary iodine intake in adults and children, respectively. Fish contributed more than 20% of the iodine intake in adults and about 10% in children. The iodine contribution of drinking water was negligible. CONCLUSIONS: While fish has the highest natural concentration of iodine and as such is an excellent iodine source, milk and diary products are the main determinants of iodine intake in the Norwegian population. Iodisation of cow fodder has been mandatory in Norway since 1950 and provides an efficient alternative to universal salt iodisation. Our results show that the dietary iodine intake of adults is in the range considered to be sufficient. The dietary intake of iodine was at recommended levels among the youngest children; however, it decreased among adolescents, especially among girls.     

Full-term, peri-urban South African infants under 6 months of age are at risk for early-onset anaemia

OBJECTIVE: There is a paucity of data on the micronutrient status of low-income, lactating South African women and their infants under 6 months of age. The aim of this study was to elucidate the level of anaemia and vitamin A deficiency (VAD) in peri-urban breast-feeding women and their young infants. DESIGN: Cross-sectional study including anthropometric, biochemical and infant feeding data.Setting: Peri-urban settlement in Cape Town, South Africa. SUBJECTS: Breast-feeding women (n=113) and their infants (aged 1-6 months) attending a peri-urban clinic. RESULTS: Mean (standard deviation (SD)) haemoglobin (Hb) of the lactating mothers was 12.4 (1.3) g dl(-1), with 32% found to be anaemic (Hb<12 g dl(-1)). Maternal serum retinol was 49.8 (SD 13.3) microg dl(-1), with 4.5% VAD. Using breast milk, mean (SD) retinol concentration was found to be 70.6 (24.6) microg dl(-1) and 15.7 (8.3) microg/g milk fat, with 13% below the cut-off level of <8 microg/g fat. There was no correlation found between breast milk retinol and infant serum retinol. Z-scores (SD) of height-for-age, weight-for-age and weight-for-height were -0.69 (0.81), 0.89 (1.01) and 1.78 (0.83), respectively. Mean (SD) infant Hb was 10.9 (1.1) g dl(-1), with the prevalence of anaemia being 50%, 33% and 12% using Hb cut-offs below 11 g dl(-1), 10.5 g dl(-1) and 9.5 g dl(-1), respectively. Mean (SD) infant serum retinol was 26.9 (7.2) microg dl(-1), with 10% being VAD. None of the infants was exclusively breast-fed, 22% were predominantly breast-fed and 78% received complementary (mixed) breast-feeding. Thirty-two per cent of infants received weaning foods at an exceptionally young age (< or =1 month old). CONCLUSION: A high rate of anaemia is present in lactating women residing in resource-poor settings. Moreover, their seemingly healthy infants under 6 months of age are at an elevated risk of developing early-onset anaemia and at lower risk of VAD.     

Breast-feeding initiation and exclusive breast-feeding in rural Vietnam

OBJECTIVE: To investigate the initiation of breast-feeding and exclusive breast-feeding within the first week after delivery for women in rural Vietnam. DESIGN: An interviewer-administered survey was conducted on a sample of rural women who gave birth during August-October 2002. SETTING: Quang Xuong District, Thanh Hoa Province of Vietnam. SUBJECTS: Four hundred and sixty-three women participated in the study, of whom 181 delivered at the district hospital (39.1%), 229 at a commune health centre (49.5%) and 53 at home attended by a traditional birth attendant (11.4%). RESULTS: Although the initiation and exclusive breast-feeding rates were relatively high at 98.3% and 83.6% respectively, the premature introduction of complementary food was a great concern. Logistic regression analysis showed that, together with socio-cultural determinants such as feeding preferences of the husband and maternal grandmother, feeding practices of friends, factors relating to delivery methods, delivery locations and health problems could influence the initiation rate and breast-feeding patterns. CONCLUSIONS: To promote breast-feeding practices of rural mothers, health education on breast-feeding should take into account local socio-cultural features in addition to improving the counselling skills of health workers.     

Breast-feeding, dietary intakes and their associations with subclinical vitamin A deficiency in children in Anhui Province, China

OBJECTIVE: This study aimed to explore the associations between breast-feeding, dietary intakes and other related factors and subclinical vitamin A deficiency (SVAD) in children aged 0-5 years in an area in China where mild vitamin A deficiency (VAD) is found. METHODS: Data were from a population-based cross-sectional study with 1052 children aged 0-5 years. SVAD cases were identified by the indicator of serum retinol相似文献   

Iodine deficiency and its association with intelligence quotient in schoolchildren from Colima, Mexico

OBJECTIVE: To determine the prevalence of iodine deficiency, its causes and its association with intelligence quotient (IQ) in Mexican schoolchildren. DESIGN: Cross-sectional analytical study, in which determinations of thyroid gland size, urinary iodine excretion, IQ, iron nutritional status, physical anthropometry, family consumption of goitrogenic foods, type/origin and iodine saturation of salt consumed at home and coliform organisms in drinking water were performed, and the association of each variable with IQ scores was evaluated by multiple regression analyses. SETTING: Municipality of Cuauhtémoc, in Colima, Mexico (altitude: 600-2700 m above sea level). Sea salt is extracted manually nearby and often used for human consumption. Goitre remains present in the region despite over half a century of mandatory salt iodination in the country. SUBJECTS: Three hundred and three children, similar proportions of boys and girls, mean age 9.3 years, randomly selected from 19 public elementary schools. RESULTS: Overall goitre rate was 21.4%; low urinary iodine excretion was found in 19.5% of the children, high urinary iodine excretion in 32.0%. IQ scores were transformed into percentile values, with the following categorisation: < or = P5 (low IQ), 48.5%; > P5 to < or = P25 (below average), 24.2%; > P25 to < P75 (average), 18.8%; > or = P75 to < P95 (above average), 3.6%; > or = P95 (high IQ), 4.9%. Ninety-two per cent of the population used iodinated salt, but deficient iodine saturation (<50 ppm) was found in 86.8% of salt samples. The main goitrogenic foods consumed were peanuts (by 31.5% of the sample), cabbage (30.1%), broccoli (27.7%) and cauliflower (25.7%). Median counts of coliform organisms (colony-forming units/100 ml of drinking water) were: 207.5 (well water), 151 (cisterns), 52 (private homes), 25 (elementary schools) and 12 (kindergartens). Moderate iodine deficiency was associated (P < 0.05) with a 4.26 times higher risk of low IQ. CONCLUSIONS: There is a perturbing negative impact of these findings on human capital acquisition for the region and the country. More attention is needed to ensure effective salt iodination processes, particularly in regions where goitrogens may contribute to the negative effects of iodine deficiency on the intellectual development of children.     

Factors associated with the initiation of breast-feeding by Aboriginal mothers in Perth

OBJECTIVES: To identify the prevalence of breast-feeding at discharge and the determinants of breast-feeding initiation amongst Aboriginal women. DESIGN: A prospective cohort study using a self-administered baseline questionnaire and telephone-administered follow-up interviews. SETTING: Six hospitals with maternity wards in Perth, Western Australia. SUBJECTS: Four hundred and twenty-five Aboriginal mothers of newborn infants. RESULTS: At discharge, 89.4% of Aboriginal mothers were breast-feeding. Breast-feeding at discharge was most positively associated with perceived paternal support of breast-feeding, with an adjusted odds ratio (OR) of 6.65 (95% confidence interval (CI) 2.81-15.74), and with maternal age (OR 1.12, 95% CI 1.03-1.22), but negatively associated with parity and having delivered vaginally. CONCLUSION: The factors independently associated with breast-feeding at discharge were similar to those previously identified for a group of non-Aboriginal Perth women, suggesting that separate breast-feeding interventions specially targeted at Aboriginal women are not warranted. The findings do, however, highlight the importance of including the father in the breast-feeding discussions.     

Breast-feeding in South Korea: factors influencing its initiation and duration

OBJECTIVE: To investigate factors influencing the practices of partial breast-feeding (PBF) and exclusive breast-feeding (EBF). DESIGN: A national, cross-sectional survey was conducted among married women aged 15-49 years from May to August 2003. SETTING: South Korea. SUBJECTS: A total of 865 mothers answered questions regarding the feeding practices of their youngest baby, born between January 2001 and May 2003. RESULTS: The initiation rates of PBF and EBF were 81% and 63%, respectively. However, the median durations of PBF and EBF were very short: 12 and 8 weeks, respectively. According to stepwise logistic and Cox regression analyses, the more prenatal care women received, the more likely they were to initiate PBF and EBF but the less likely to continue EBF. Delivery by Caesarean section decreased the initiation of PBF and EBF. The mother's education level and employment status before marriage, the amount of prenatal care, delivery method and baby's status at birth affected breast-feeding initiation, whereas the amount of prenatal care influenced breast-feeding duration. CONCLUSION: To promote breast-feeding, education and campaigning on the importance of continued breast-feeding should be provided to the general public, particularly to health workers in maternity units.     

Maize meal fortification is associated with improved vitamin A and iron status in adolescents and reduced childhood anaemia in a food aid-dependent refugee population

OBJECTIVE: To assess changes in the Fe and vitamin A status of the population of Nangweshi refugee camp associated with the introduction of maize meal fortification. DESIGN: Pre- and post-intervention study using a longitudinal cohort. SETTING: Nangweshi refugee camp, Zambia. SUBJECTS: Two hundred and twelve adolescents (10-19 years), 157 children (6-59 months) and 118 women (20-49 years) were selected at random by household survey in July 2003 and followed up after 12 months. RESULTS: Maize grain was milled and fortified in two custom-designed mills installed at a central location in the camp and a daily ration of 400 g per person was distributed twice monthly to households as part of the routine food aid ration. During the intervention period mean Hb increased in children (0.87 g/dl; P < 0.001) and adolescents (0.24 g/dl; P = 0.043) but did not increase in women. Anaemia decreased in children by 23.4% (P < 0.001) but there was no significant change in adolescents or women. Serum transferrin receptor (log10-transformed) decreased by -0.082 microg/ml (P = 0.036) indicating an improvement in the Fe status of adolescents but there was no significant decrease in the prevalence of deficiency (-8.5%; P = 0.079). In adolescents, serum retinol increased by 0.16 micromol/l (P < 0.001) and vitamin A deficiency decreased by 26.1% (P < 0.001). CONCLUSIONS: The introduction of fortified maize meal led to a decrease in anaemia in children and a decrease in vitamin A deficiency in adolescents. Centralised, camp-level milling and fortification of maize meal is a feasible and pertinent intervention in food aid operations.     

Knowledge of iodine nutrition in the South African adult population

OBJECTIVES: To determine the level of knowledge regarding iodine nutrition and its relationship with socio-economic status in the South African population. DESIGN: A cross-sectional population survey collecting questionnaire information on knowledge of iodine nutrition and sociodemographic variables in a multistage, stratified, cluster study sample, representative of the adult South African population. SETTING: Home visits and personal interviews in the language of the respondent.Subjects: Data were collected from one adult in each of the selected 2164 households, and the participation rate was 98%. RESULTS: Only 15.4% of respondents correctly identified iodised salt as the primary dietary source of iodine, 16.2% knew the thyroid gland needs iodine for its functioning, and a mere 3.9% considered brain damage, and 0.8% considered cretinism, as the most important health consequence of iodine deficiency. Compared with respondents from high socio-economic households, respondents from low socio-economic households were considerably less informed about aspects of iodine nutrition covered in this study. CONCLUSIONS: The knowledge level of iodine nutrition is low among South Africans, particularly among the low socio-economic groups. These data suggest that the international emphasis on brain damage resulting from iodine deficiency has not been conveyed successfully to the consumer level in this country.     

Increased prevalence of hyperthyroidism as an early and transient side-effect of implementing iodine prophylaxis

OBJECTIVE: To assess the prevalence of hyperthyroidism just after implementation of iodine prophylaxis among adults from an area with iodine deficiency. STUDY DESIGN AND SUBJECTS: A total of 1648 adults (age 16 years and older) were sampled from an area of southern Poland during two nationwide epidemiological surveys. Of these, 1424 adults with negative medical history for thyroid disorders qualified for final analysis. The authors compared thyroid dysfunction in participants prior to (1989-1990) and after implementation of iodine prophylaxis (1997-1999). SETTING: The southern part of Poland. RESULTS: We found an increase in the serum concentration of anti-thyroid microsomal antibodies from 4.9% in the years 1989-1990 to 12.1% after introduction of iodised household salt (P < 0.0001). The prevalence of hyperthyroidism (defined as thyroid-stimulating hormone < 0.4 microU ml- 1) significantly increased in the equivalent period from 4.8 to 6.5% (P = 0.009). CONCLUSIONS: We concluded that a sudden rise in iodine intake after implementation of iodine prophylaxis among adults from the area with iodine deficiency may lead to an increase in thyroid autoimmunity and prevalence of hyperthyroidism. Those possible early side-effects appear to be only temporary and are acceptable when compared with the evident benefits of adequate iodine intake.     

Folate deficiency is associated with nutritional anaemia in Lebanese women of childbearing age

OBJECTIVE: The objective of this study was to identify the determinants of anaemia in Lebanese women of childbearing age attending health centres in Lebanon. DESIGN: Cross-sectional study carried out between May and December 2003. Anthropometric measurements as well as sociodemographic, health and dietary intake data were collected using a questionnaire. Haemoglobin (Hb), plasma ferritin, plasma folate and vitamin B12 were assessed using standard laboratory methods. SETTING: Governmental health centres in Lebanon. SUBJECTS: Four hundred and seventy non-pregnant Lebanese women aged 15-45 years. RESULTS: Anaemia (Hb <12 g dl(-1)) and iron deficiency (ferritin <15 microg l(-1)) were prevalent in 16.0 and 27.2% of the study sample, respectively. Of the total sample, 7.7% had iron-deficiency anaemia. The percentage of women with either Hb or ferritin deficiency or both was 35.6%. Plasma folate and vitamin B12 deficiency was reported in 25.1 and 39.4%, respectively, and 12.6% of the women had both folate and vitamin B12 deficiencies. Of the anaemic group, 48.0% of the women had iron deficiency. The intake of iron was lower in iron-deficient than in non-deficient women and a positive relationship was shown between folate intake and its corresponding serum levels. Regression analysis showed that ferritin, plasma folate and family history of anaemia were significant determinants of the anaemia in the sample of women. CONCLUSIONS: Anaemia not related to iron deficiency was partly explained by plasma folate deficiency. Measures to control folate and iron deficiency should be considered.     

Comparison of blood folate levels among pregnant Chinese women in areas with high and low prevalence of neural tube defects

OBJECTIVE: To characterise plasma and red-blood-cell (RBC) folate status among pregnant women in an area with an extremely high prevalence of neural tube defects, and to compare them with those of women from a low prevalence area. DESIGN: A cross-sectional survey conducted in 2003. SETTING: One county and one city from each of the high prevalence area and the low prevalence area in China. SUBJECTS: Five hundred and sixty-two women in their first trimester of pregnancy in the high prevalence area and 695 pregnant women in the low prevalence area. RESULTS: Women in the high prevalence area had less than half the plasma and RBC folate concentrations (12.2 and 440.0 nmol l- 1, respectively) of women in the low prevalence area (33.5 and 910.4 nmol l- 1, respectively). In the high prevalence area, 40% of rural women were deficient in RBC folate and 50% were deficient in plasma folate; 20% of urban women were deficient in RBC folate and 30% deficient in plasma folate. In contrast, only 4% (RBC folate) and 6% (plasma folate) of rural women, and 2% (RBC folate) and 1% (plasma folate) of urban women, were folate-deficient in the low prevalence area. Less than 10% of rural and about 26% of urban women in the high prevalence area took folic acid periconceptionally, compared with 70% and 60% of women in the low prevalence area. CONCLUSIONS: Blood folate deficiency is highly prevalent among pregnant women in an area of China with a very high prevalence of neural tube defects.     

基于典型县入户调查的中国农村家庭能源消费研究

农村家庭能源消费是国家能源消费中的重要组成部分,对农村社会、生态环境的发展有重要影响。该研究对中国8大经济区的典型县的1 440个家庭进行了派员式入户调查。调查数据分析表明,不同区域的农村家庭能源消费水平和结构有很大差异,8县年人均能源消费平均为26.7 GJ,最低10.4 GJ(上杭县),最高86.6 GJ(舒兰县)。在能源消费中秸秆、沼气、薪柴、电力所占比例8县平均分别为44.33%、23.13%、12.79%、9.61%。收入较高的农村家庭使用着更多的电力、液化石油气等商品能源,较少使用秸秆、薪柴等生物质能;从总体上,传统生物质能仍然是中国农村家庭的主要能源。该研究为掌握中国农村地区家庭能源消费现状和未来发展,制定相关能源、环境政策提供了依据。     

Validation of the Radimer/Cornell food insecurity measure in rural Kilimanjaro, Tanzania

OBJECTIVE: The objective of the present study was to assess the construct validity, criterion-related validity and internal consistency of the Radimer/Cornell food insecurity measure for use in rural Tanzania. DESIGN: A cross-sectional community-based survey was conducted from March to May 2005. Key adaptations to the nine-item Radimer/Cornell items included translation to Swahili, replacing the term 'balanced diet' with 'full meal' and constructing the items as questions rather than statements. Factor analysis and Cronbach's alpha were used to assess validity and reliability, respectively. SETTING: Rural Kilimanjaro, Tanzania. SUBJECTS: Analysis was restricted to data from 530 women aged 15-44 years who had children under 5 years old. RESULTS: Principal component factor analysis revealed a two-factor solution: (1) altered eating pattern at household level and (2) altered eating pattern at child level. The two factors accounted for 66.2% of the total variance. The subscales developed had good reliability. Internal consistency of the scales was 0.853 and 0.784 for food insecurity at household level and food insecurity at child level, respectively. Only 14.0% of the women reported to be food-secure and 86.0% reported some kind of food insecurity. The Radimer/Cornell food insecurity measure showed significant associations with selected sociodemographic factors in the expected directions. There was also an association with the NHANES III (Third National Health and Nutrition Examination Survey) and CCHIP (Community Childhood Hunger Identification Project) indicators. CONCLUSION: Our findings suggest that the adapted Radimer/Cornell measure may have some utility in assessing food insecurity in settings like rural Tanzania.     

Effect of economic inequality on chronic childhood undernutrition in Ghana

OBJECTIVE: Food insecurity and undernutrition remain particularly severe in developing countries where improvements in economic conditions have tended to benefit the advantaged groups and resulted in widespread inequalities in health. This study examined how economic inequality is associated with chronic childhood undernutrition. DESIGN: A child was defined as chronically undernourished (stunted) if his or her height-for-age index was more than two standard deviations below the reference median. Household economic status was measured by an index based on household ownership of durable assets. Bivariate and multivariate analyses were used to estimate the effects of household economic status on stunting. SETTING: A nationally representative sample of 6251 household interviews in Ghana.Subjects A total of 3077 children aged 0-59 months included in the 2003 Ghana Demographic and Health Survey. RESULTS: Children in the poorest 20% of households are more than twice as likely to suffer from stunting as children in the richest 20% of households independent of the child's age, sex, birth order, breast-feeding duration, birth weight; mother's age at childbirth, body mass index, education; and household access to safe drinking water, hygienic toilet facilities, residence and geographic region (odds ratio = 2.3; 95% confidence interval 1.4-3.7). Also children in the next poorest and in the middle quintiles are significant more likely to be chronically undernourished than children in the richest 20% of households. CONCLUSION: This study concludes that economic inequality is strongly associated with chronic childhood undernutrition; and reducing economic inequalities and making services more accessible to the poor will be key to improving the health and nutritional status of children in Ghana.     

生计转型背景下河北省农村宅基地整理分区与潜力研究

基于农户生计转型背景对河北省农村宅基地整理进行分区调控,并基于不同整理目标测算农村宅基地整理潜力与面积标准。结果显示:受农户非理性决策影响,户均宅基地面积随农户非农就业程度的提升呈现先减小后增大的趋势,非农就业拐点在0.496～0.564之间,城镇化率、人均耕地面积、农业分区、宅基地容积率、人均GDP对各县域户均宅基地面积产生不同方向和程度的影响。由此,划分了优先整理、适度整理、适度挖潜、限制整理4类整理时序分区,以宅基地制度改革、农业结构优化、深化农村土地管理水平为工作导向的5类整理模式分区。优先整理区宅基地整理潜力为45 429.70 hm~2,户均宅基地面积标准为401m~2,经济条件是限制宅基地整理的主要因素;适度整理区宅基地整理潜力为446.32 hm~2,户均宅基地面积标准为26 m~2,宅基地用地需求较小;适度挖潜区宅基地整理潜力为33 471.92 hm~2,户均宅基地面积标准为407 m~2,自然、经济条件是限制宅基地整理的主要因素。     

太湖流域农村生活垃圾产排污系数测算研究

选取太湖流域典型农村9户农户（高、中、低收入水平各3户农户）作为研究对象,采用现场监测及入户调查的方法对农户生活垃圾污染物产排系数进行为期一年的系统定量研究,结果表明：收入水平对农户总垃圾、有机垃圾、有机垃圾TN、TP产排污系数及可回收垃圾产污系数影响极显著（P〈0.01）,具体表现为高收入农户〉中收入农户〉低收入农户,但对农户有害垃圾产排污系数及可回收垃圾排污系数无显著性影响（P〉0.05）。因此,除有害垃圾产排污系数及可回收垃圾排污系数外,农户总垃圾、有机垃圾、有机垃圾TN、TP产排污系数及可回收垃圾产污系数可按收入水平划分。各收入水平农户有机垃圾占总垃圾比例超过80%,表明有机垃圾的综合利用效率特别是畜禽养殖率是影响生活垃圾污染物排放系数的主导因素,而农业收入水平则对这种因素影响显著。