A two-generational reproductive toxicity study of zinc in rats

A two-generation reproductive toxicity study of zinc chloride (ZnCl(2)) was conducted in rats. F(o) male and female rats were administered 0.00 (control), 7.50 (low), 15.00 (mid) and 30.00 (high) mg/kg/day of ZnCl(2). Selected F(1) male and female rats were exposed to the same doses received by their parents (F(o)). Exposure of F(0) parental rats to ZnCl(2) showed significant reduction in fertility, viability (days 0 and 4), and the body weight of F(1) pups from the high-dose group but caused no effects on litter size, weaning index, and sex ratio. Similarly, the continued exposure of F(1) parental rats to ZnCl(2) also reduced fertility, liter size, viability (day 0), and the body weight of F(2) pups within the high-dose group but caused no effects on weaning index and sex ratio. Exposure of ZnCl(2) to F(0) and F(1) parental males resulted in a significant reduction in their body weights, and the F(0) and F(1) parental females did not show any significant difference in their body weights compared to their control groups. However, the postpartum dam weights of both F(0) and F(1) female rats were significantly reduced compared to their controls. Exposure of ZnCl(2) to F(o) and F(1) generation parental rats did not produce any significant change of their clinical signs as well as their clinical pathology parameters, except the alkaline phosphotase (ALK) level, which showed an upward trend in both sexes of both generations. Exposure of ZnCl(2) to F(0) rats resulted in a reduction of brain, liver, kidney, spleen and seminal vesicles weights of males and in the spleen and uterus of females. Similarly, exposure of F(1) rats to ZnCl(2) also resulted in reduction of brain, liver, kidney, adrenal, spleen, prostate and seminal vesicles weights of males and in spleen and uterus of females. ZnCl(2) exposure resulted in grossly observed gastro-intestianla (GI) tract, lymphoreticular/hematopoietic, and reproductive tract lesions in parental rats in both generations. Reduced body fat was also recorded in F(1) parental rats.     

Fluorine distribution in aquatic environment and its health effect in the Western Region of the Songnen Plain, Northeast China

Endemic fluorosis was investigated and studied in the west region of the Songnen plain, Northeast China in 2001–2002. The results showed that the fluorine distribution in aquatic environment was that the fluorine concentrations in the lake water and unconfined ground water were higher than that in the river water and confined ground water. The lake water (Alkali lake) is connected with unconfined ground water. In unconfined ground water, from the east and southeast areas to the west and the northwest areas of the plain, fluorine concentration fluctuated with high and low alternatively. The fluorine in the water comes from the weathering of rocks and minerals in the mountains and hills around the Songnen Plain. The main influence factors of the fluorine distribution in aquatic environment are discussed. Unconfined ground water containing high fluorine is used as drinking water. In this region, the fluorine concentration in drinking water is evidently correlated to the morbidity of dental and skeletal fluorosis. High fluorine concentration in drinking water has endangered human health.     

Characteristics and driving factors of marsh changes in Zhalong wetland of China

Zhalong National Nature Reserve in the northeast of China is a large wetland and a habitat of hundreds species of fauna and flora. The rare red-crowned crane is one kind of endangered birds in it. Recently, Zhalong wetland is shrinking and it encounters many problems including occasional fires, bad water quality, human activities, etc. In order to find out a proper way to protect and restore the wetland, this study, using a geographic information system, the global positioning system and remote sensing techniques, analyses the spatial characteristics of the changes in marsh landscape pattern and examines the driving factors for these changes. Data sources include 8 Landsat Thematic Mapper satellite images of Zhalong area in the period of 1986–2002 and the investigation information on site. Based on the analysis of changes of marsh area and annual precipitation during the 16 years, it is found that there is a close correlation between annual precipitation and marsh area. It means that climate is one of driving factors of marsh pattern changes. To understand influences of other kinds of land uses on marsh spatial distribution in Zhalong wetland, this paper analyses the relationship between marsh and different kinds of land uses, such as water surface, residential area, farmland, salina land and grass land, respectively. According to the patch analysis theory, a fragmental index and a fractal dimension of the marsh are calculated with perimeter-area method. The results indicate that the marsh pattern is affected by human activities significantly. In addition, the location alteration of marsh centroid point over the 16 years is studied. The movement trace of marsh centroid point is concerned with different hydrological situation in different areas of the wetland. In summary the characteristics of the marsh landscape pattern evolution during the 16 years are affected by multiple driving factors. The main driving factors are climate, human activities, distribution of other kinds of land uses and hydrological situation in different areas.     

Influence of Relative Humidity and Ozone on the Sampling of Volatile Organic Compounds on Carbotrap/Carbosieve Adsorbents

By using a dynamic dilution system, the atmospheric measurement of 11 selected toxics VOCs (ethylene, acetylene, propene, 1-butene, 1,3-butadiene, 1-pentene, 1-hexene, benzene, toluene, ethylbenzene, m+p-xylene) from the list WHO of 1996 and TO-14 method of US EPA by preconcentration by thermal desorption (TD), analysis by gas chromatography (GC), identification and quantification with a flame ionisation detector (FID) was developed and validated in term of metrology, especially the techniques of sampling of these VOCs with adsorbents cartridges "Air Toxics" when used with an "UMEG sampler" equipped in the inlet with a nafion membrane. In particular the influence of climatic conditions (temperature and relative humidity) and the influence of chemical factors like ozone, on the representativity of sampling were studied. Experiments made with various humidities showed that the addition of a nafion membrane in the inlet of the sampling system was required. Without this membrane, losses of compounds were observed for RH >50%. With this membrane, storage for 2 weeks in a refrigerator, as for canisters, did not induce a loss of compounds. No significative decrease of concentrations of the studied VOCs after 14 days storage, which are known to react with ozone, were observed with an ozone concentrations of 55 ppb. One explanation is that nafion membrane, placed in the inlet of the sampler, will neutralize ozone before entering the sampling tubes. This observation is in accordance with literature which states that the sampling of VOCs on Carbotrap cartridges without ozone scrubber induce a loss of compounds.     

Effects of sewage sludge amendment on heavy metal accumulation and consequent responses of Beta vulgaris plants

Use of sewage sludge, a biological residue produced from sewage treatment processes in agriculture is an alternative disposal technique of waste. To study the usefulness of sewage sludge amendment for palak (Beta vulgaris var. Allgreen H-1), a leafy vegetable and consequent heavy metal contamination, a pot experiment was conducted by mixing sewage sludge at 20% and 40% (w/w) amendment ratios to the agricultural soil. Soil pH decreased whereas electrical conductance, organic carbon, total N, available P and exchangeable Na, K and Ca increased in soil amended with sewage sludge in comparison to unamended soil. Sewage sludge amendment led to significant increase in Pb, Cr, Cd, Cu, Zn and Ni concentrations of soil. Cd concentration in soil was found above the Indian permissible limit in soil at both the amendment ratios.

The increased concentration of heavy metals in soil due to sewage sludge amendment led to increases in heavy metal uptake and shoot and root concentrations of Ni, Cd, Cu, Cr, Pb and Zn in plants as compared to those grown on unamended soil. Accumulation was more in roots than shoots for most of the heavy metals. Concentrations of Cd, Ni and Zn were more than the permissible limits of Indian standard in the edible portion of palak grown on different sewage sludge amendments ratios. Sewage sludge amendment in soil decreased root length, leaf area and root biomass of palak at both the amendment ratios, whereas shoot biomass and yield decreased significantly at 40% sludge amendment. Rate of photosynthesis, stomatal conductance and chlorophyll content decreased whereas lipid peroxidation, peroxidase activity and protein and proline contents, increased in plants grown in sewage sludge-amended soil as compared to those grown in unamended soil.

The study clearly shows that increase in heavy metal concentration in foliage of plants grown in sewage sludge-amended soil caused unfavorable changes in physiological and biochemical characteristics of plants leading to reductions in morphological characteristics, biomass accumulation and yield. The study concludes that sewage sludge amendment in soil for growing palak may not be a good option due to risk of contamination of Cd, Ni and Zn and also due to lowering of yield at higher mixing ratio.     

Survey of heavy metal pollution and assessment of agricultural soil in Yangzhong district, Jiangsu Province, China

We investigated concentrations of Hg, Cd, Pb, Zn, Cu, As, Ni, and Cr in samples of soil, cereal, and vegetables from Yangzhong district, China. Compared to subsoils, the sampled topsoils are enriched in Hg, Cd, Cu, Pb, Zn, and As. High levels of Cd and Hg are observed in most agricultural soils. Concentrations of Cr and Ni show little spatial variation, and high Cu, Pb, and Zn contents correspond well to areas of urban development. High As contents are primarily recorded at the two ends of the sampled alluvion. The contents of Cd, Hg, and total organic carbon (TOC) increase gradually to maximum values in the upper parts of soil profiles, while Cr and Ni occur in low concentrations within sampled profiles. As, Pb, Cu, and Zn show patterns of slight enrichment within the surface layer. Compared to data obtained in 1990, Cd and Hg show increased concentrations in 2005; this is attributed to the long-term use of agrochemicals. Cr and Ni contents remained steady over this interval because they are derived from the weathering of parent material and subsequent pedogenesis. The measured As, Cu, Pb, and Zn contents show slight increases over time due to atmospheric deposition of material sourced from urban anthropogenic activity. Low concentrations of heavy metals are recorded in vegetables and cereals because the subalkaline environment of the soil limits their mobility. Although the heavy metal concentrations measured in this study do not pose a serious health risk, they do affect the quality of agricultural products.     

High levels of organochlorines in mothers' milk from Chennai (Madras) city, India

Mothers' milk from Chennai (formerly Madras), India and three other places Perungudi, the municipal dumping site of south Chennai area (situated at the suburb of Chennai), Chidambaram, a predominantly agricultural town situated 250 km south of Chennai and Parangipettai, a fishing village 15 km north of Chidambaram, all situated at or near the southeastern Bay of Bengal coast of India were found to contain measurable concentrations of HCHs, DDTs, PCBs, CHLs and HCB. A notable finding in this study is that Chennai mothers have higher levels of HCHs in their milk and hence may transfer considerably higher amounts of the chemical than the mothers from all the other three places of the present study indicating a higher health risk to Chennai's children. It was also found that the levels of the two organochlorine pesticides (HCHs and DDTs) increased in Chennai mothers' milk in the last decade. Food items collected from Chennai markets did not show any remarkably higher levels of any of the chemicals measured in this study. Levels of the two classical organochlorines (DDTs and HCHs) have declined in many of the food items when compared with our data collected two decades before in the same locations, showing the effectiveness of the recent ban on both these chemicals in the country. The sources, possible health risks and the ways to curtail the effects of HCHs, especially at Chennai, should be investigated further.     

Ability of fungi to degrade synthetic polymer nylon-6

Fifty-eight fungi have been tested for their ability to degrade a recalcitrant synthetic polymer polyamide-6, generally known as nylon-6. Most of them were isolated from a factory producing nylon-6. After preliminary screening, 12 strains were selected for submerged culture in a medium with nylon fibres as the only N-source. No degradation was observed with the isolates from the factory. Wood degrading fungi from a culture collection, however, degraded nylon after incubation for several weeks. Bjerkandera adusta disintegrated the fibres most efficiently, starting with the small transverse grooves, which deepened into cracks. The superficial layers crumbled to leave a thin inner core of the fibre, which finally broke down into fragments. The remaining insoluble part of the nylon showed a decrease in number average molecular mass from 16900 to 5600 during a 60-day incubation. Its thermal properties, such as shifts in melting points and broadening of the melting endotherms, were altered. The reduction of the amount of nylon and the composition of the liquid phase indicated that part of the polymer was degraded into soluble products. After 50 days, the total nitrogen content of the soluble fraction was 10-fold higher than in the control sample. Manganese peroxidase, presumably responsible for the degradation, was detected in the liquid phase. The study shows that only white rot fungi are able to break down nylon-6. For the first time this polymer was shown to be disrupted by B. adusta. The extent of the biodegradation indicates its potential for application in nylon waste reduction.     

Uptake and accumulation of cadmium, lead and zinc by Siam weed [Chromolaena odorata (L.) King & Robinson

The Siam weed, Chromolaena odorata (L.) King & Robinson, Family Asteraceae, was found to be a new Pb hyperaccumulator by means of field surveys on Pb soil and hydroponic studies. Plants from field collection accumulated 1377 and 4236mgkg(-1) Pb in their shoots and roots, respectively, and could tolerate soil Pb concentrations up to 100000 mgkg(-1) with a translocation factor of 7.62. Very low concentrations of Cd and Zn were found in plants collected from the field. Under nutrient solution culture condition, C. odorata from the contaminated site (CS) and from non-contaminated site (NCS) grew normally with all three metals (Pb, Cd, Zn) supplied. However, the relative growth rates of all treated plants decreased with increased metal concentrations. The percentage uptakes of Pb, Cd, and Zn by C. odorata increased with increasing metal concentrations. Pb concentration in shoots and roots reached its highest values (1772.3 and 60655.7mgkg(-1), respectively) at a Pb supply level of 10mgl(-1). While the maximum concentrations of Cd (0.5mgl(-1)) in shoots and roots of C. odorata were 102.3 and 1440.9mgkg(-1), and the highest concentrations of Zn (20mgl(-1)) were 1876.0 and 7011.8mgkg(-1), respectively. The bioaccumulation coefficients of Pb and Cd were greater than 1000. These results confirm that C. odorata is a hyperaccumulator which grows rapidly, has substantial biomass, wide distribution and has a potential for the phytoremediation of metal contaminated soils.     

Persistent organic pollutants in 9/11 world trade center rescue workers: reduction following detoxification

Exposure to toxins following the September 11, 2001 attack on and collapse of the World Trade Center (WTC) is of particular concern given the ultra fine particulate dust cloud, high temperature combustion, and months-long fire. Firefighters, paramedics, police and sanitation crews are among the approximately 40000 personnel who labored for weeks and months on rescue and cleanup efforts. Many of the rescue workers have subsequently developed symptoms that remain unresolved with time. This study characterizes body burdens of polychlorinated biphenyls (PCBs), polychlorinated dibenzofurans (PCDFs), and polychlorinated dioxins (PCDDs) in rescue workers and citizens exposed following the WTC collapse. Our research includes a pilot evaluation of a detoxification method aimed at reducing toxic burden. Many congeners were found at elevated levels, in ranges associated with occupational exposures. Post-detoxification testing revealed reductions in these congeners and despite the small study size, some reductions were statistically significant. Health symptoms completely resolved or were satisfactorily improved on completion of treatment. These results argue for a larger treatment study of this method and an overall treatment approach to address toxic burden.