Analysis of heavy metals and toxicity level in the tannery effluent and the environs

Heavy metals have found a large number of applications in the recent times. These heavy metals are being continuously added to our environment through various natural and anthropogenic activities. Industries employ heavy metals to process raw materials into final products. Effluents from these industries carry heavy metals. Atomic absorption spectrophotometer and ICP-MS (inductively coupled plasma-mass spectrometer) are of great help in detecting various elements in the effluent. They have been extensively applied to solve problems related to environmental monitoring and assessment. Heavy metals like Cu, Cd, Ni, Pb, and Cr can be easily detected using both the techniques. Some of these heavy metals are toxic to both humans and animals. They can have significant related health effects. Presence of heavy metals in the industrial effluent has gained varied attention in the recent times and it has become one of the major causes of water and soil pollution. Significant contributions can be linked with the leather tanning industry. As the effluent from the tanning industry has been found to contain a large number of heavy metals in many studies. Continuous monitoring and treatment of the effluent is necessary to keep a check on the concentration of heavy metals in these effluents. This study focuses on the analysis of the various studies available on tannery effluents, methods used for heavy metal analysis, toxicity of these heavy metals, and the related major health effects. Data for heavy metals in the tannery effluent from different studies in last two decades has been collected and analysed. The data from various studies indicates that Cr, Cd, Pb, Zn, Cu, Fe, and Ni are the most commonly found heavy metals released from the tanning industry. Proper management of the tannery effluent is thus very essential for saving the environment.

Metabolic pathway of Cr(VI) reduction by bacteria: A review

Heavy metal wastes, particularly hexavalent chromium [Cr(VI)], are generated from anthropogenic activities, and their increasing abundance has been a research concern due to their toxicity, genotoxicity, carcinogenicity and mutagenicity. Exposure to these dangerous pollutants could lead to chronic infections and even mortality in humans and animals. Bioremediation using microorganisms, particularly bacteria, has gained considerable interest because it can remove contaminants naturally and is safe to the surrounding environment. Bacteria, such as Pseudomonas putida and Bacillus subtilis, can reduce the toxic Cr(VI) to the less toxic trivalent chromium Cr(III) through mechanisms including biotransformation, biosorption and bioaccumulation. These mechanisms are mostly linked to chromium reductase and nitroreductase enzymes, which are involved in the Cr(VI) reduction pathway. However, relevant data on the nitroreductase route remain insufficient. Thus, this work proposes an alternative metabolic pathway of nitroreductase, wherein nitrate activates the reaction and indirectly reduces toxic chromium. This nitroreductase pathway occurs concurrently with the chromium reduction pathway.

A modified approach to Industrial Pollution Projection System for the assessment of sectoral pollution loads in Bangladesh

Industrial pollution in Bangladesh has posed a serious threat to human health, economic activity, and the environment. By emphasizing industries that produce major pollutants, substantial improvements can be made to pollution mitigation measures. In countries where primary pollution data is not readily available, the Industrial Pollution Projection System (IPPS) could be used to calculate the pollution load utilizing total industrial output or employment data. IPPS data, which was designed for developed countries like the USA, had been used directly for other countries without any normalization in previously reported studies. The main purpose of this study is to modify the current IPPS approach for any other country by incorporating specific correction factor for a specific country. In this study, a specific correction factor for Bangladesh was determined, taking into account the country's major polluting industries, and used to estimate the pollution scenario for the year 2020. The accuracy of the specific pollution intensities was also evaluated by comparing the data obtained using both gross output and employee number. According to this study, the top three air-polluting industries are structural clay products, cement-lime-plaster industry, and iron and steel industry. Similarly, for water pollution, the food industry, paper and paper product industry, and textile industry are the largest pollutant contributors. The detailed pollution load matrix in terms of air and water pollution is also developed, and can be used to predict both short-term and long-term scenarios of industrial pollution in Bangladesh, which eventually will assist the policy makers to adopt appropriate pollution management approach. Moreover, the methods developed in this study will help to tailor the IPPS data for any country and increase the accuracy of the pollution load.

Cr (III) genotoxicity and oxidative stress: An occupational health risk for leather tannery workers of South Asian developing countries

In the leather industry, Cr (III) is used as a basic tanning agent. The wastewater discharged from the tannery industry contains a high concentration of chromium. Recent studies indicate the genotoxic effects especially DNA damage and oxidative stress of Cr (III) in tannery workers. Cr (III) interacts with DNA to form DNA cross-links and DNA strand breaks. It also modifies the oxidative DNA base through the Haber–Weiss reaction. The present study is based on an overview of scientific literature and previous observations regarding the effects of tannery chromium effluents on exposed workers and the population in the vicinity. This study strongly suggests for use of a non-toxic substitute of chromium to be used for the tanning process and placement of tannery industries on the outskirts of the city. In South Asian developing countries like India, Pakistan and Bangladesh where the economy is strongly dependent on leather manufacturing industries, there is a need to spread proper information regarding the harmful effects of chromium toxicity to the workforce employed in the tannery and also to the people living in the surrounding area. Workers should be provided with the required safety protections like gloves, aprons, foot/shoe covers, masks, etc. Last but most important on an immediate basis is the installation of the proper efficient waste treatment plant, so that, waste should be treated before moving out of the industry.

Biochar Mediated-Alleviation of Chromium Stress and Growth Improvement of Different Maize Cultivars in Tannery Polluted Soils

Soil pollution with heavy metal is a serious problem across the globe and is on the rise due to the current intensification of chemical industry. The leather industry is one of them, discharging chromium (Cr) in huge quantities during the process of leather tanning and polluting the nearby land and water resources, resulting in deterioration of plant growth. In this study, the effects of biochar application at the rate of 3% were studied on four maize cultivars, namely NK-8441, P-1543, NK-8711, and FH-985, grown in two different tannery polluted Kasur (K) and Sialkot (S) soils. Maize plants were harvested at vegetative growth and results showed that Cr toxicity adversely not only affected their growth, physiology, and biochemistry, but also accumulated in their tissues. However, the level of Cr toxicity, accumulation, and its influence on maize cultivars varied greatly in both soils. In this pot experiment, biochar application played a crucial role in lessening the Cr toxicity level, resulting in significant increase in plant height, biomass (fresh and dry), leaf area, chlorophyll pigments, photosynthesis, and relative water content (RWC) over treatment set as a control. However, applied biochar significantly decreased the electrolyte leakage (EL), antioxidant enzymes, lipid peroxidation, proline content, soluble sugars, and available fraction of Cr in soil as well as Cr (VI and III) concentration in root and shoot tissues of maize plant. In addition to this, maize cultivar differences were also found in relation to their tolerance to Cr toxicity and cultivar P-1543 performed better over other cultivars in both soils. In conclusion, biochar application in tannery polluted soils could be an efficient ecofriendly approach to reduce the Cr toxicity and to promote plant health and growth.

Water Pollution in a Densely Populated Megapolis, Dhaka

Rapid urbanization has been a boon for industrial growth in Bangladesh, leading the Dhaka megapolis to become one of the least livable places in the world. These circumstances, however, have received little attention by policy makers and in academic research. Using mainly secondary data, this article explores the water quality of the river Buriganga that flows across Dhaka and identifies major sources of pollutants. While much of the article analyzes the sources and extent of pollution, it also points toward a great threat to public health from the presence of high levels of heavy metals, such as chromium, lead, and iron, as well as chemicals, including ammonia and phosphate. Moreover, the article recommends some policy changes that could potentially reduce pollution levels and boost water sustainability not only in Dhaka but also in other fast-growing cities in the least developed countries (LDCs).

Factors Associated With Health Complaints Among Leather Tannery Workers in Bangladesh

Background: Few studies have reported associations between occupational exposure to tannery chemicals with breathing difficulty and skin diseases and none have been conducted in Bangladesh. The aim of this study was to investigate the associations of health complaints with types of work and length of employment among tannery workers in Bangladesh, where occupational health and safety regulations are less restricted compared with the developed world. Methods: One hundred sixty-seven (n = 167) workers from 10 tanneries were interviewed using a questionnaire adapted from the European Community Respiratory Health Survey (ECRHS) and the Tasmanian Longitudinal Health Study (TAHS) to collect information on occupational exposures and health outcomes. Workers' length of employment was examined, as well as their areas of work including beamhouse, wet finishing, dry finishing, and miscellaneous. Univariate and multivariate logistic regressions were performed to investigate potential associations while controlling for confounders. Results: Length of employment was positively associated with breathing difficulty (odds ratio [OR]: 1.32, 95% confidence interval [CI]:1.07-1.64). Workers involved in the wet finishing (OR: 11.75, 95% CI: 2.12-65.10) and dry finishing (OR: 13.38, 95% CI: 1.00-181.70) had higher odds of breathing difficulty; while, working in the beamhouse was associated with an increased risk of developing skin diseases (OR: 4.36, 95% CI: 1.10-17.32). Conclusion/Application to Practice: Length of employment and types of work were associated with increased risk of health complaints, including breathing difficulty and skin disease among tannery workers. Stronger regulations with regular enforcement, regular health surveillance, and worker and employer education are necessary for reducing these exposures and improving the health outcomes of the tannery workers.

Modelling heavy metals in the Buriganga River System, Dhaka, Bangladesh: Impacts of tannery pollution control

Heavy metal pollution from tanneries is a global problem in many rapidly developing economies. Effluent discharges into rivers cause serious problems for water quality, damaging ecology and threatening the livelihoods of people, especially in developing urban centres which often have a high concentration of factories. The industry intensive capital area of Bangladesh is impacted with high levels of metals pollution in rivers in the Greater Dhaka Watershed. Sampling and modelling studies have been undertaken to assess pollution in the Buriganga River System in Dhaka. The process based, dynamic model INCA (Integrated Catchments) model has been used to simulate metals along the Buriganga River System in Central Dhaka. Observed and simulated metals concentrations are high, and the model shows that the proposed transfer of the tannery industry upstream helps to reduce the pollution significantly downstream. However, moving the industry upstream may be counterproductive as it is discharged into the upper reaches of the river. This will create pollution upstream unless the newly constructed effluent treatment system can operate at a high level.

Occupational risk factors associated with respiratory symptoms among tannery workers in Mojo town, Southeast Ethiopia, 2018: a comparative cross-sectional study

Introduction

Work-related respiratory diseases (WRDs) account for 10-20% of all chronic respiratory illnesses affecting hundreds of millions of people of all ages. Tannery industries are often associated with hazardous working conditions favourable for respiratory conditions. However, information about the prevalence and occupational factors that predispose to respiratory symptoms is meagre in Ethiopia. This study aimed to investigate the magnitude and risk factors associated with work-related respiratory symptoms among tannery industry workers in Mojo town, Ethiopia.

Methods

A comparative cross-sectional study was conducted from March to May 2018. A total of 602 (299 exposed to tannery factories) and 303 unexposed (civil servants) were included using the stratified sampling method. The British Medical Research Council (BMRC) questionnaire was pretested and interviewer-administered for data collection. A binary logistic regression analysis was performed to identify the factors associated with respiratory symptoms. The significance of associations was ascertained at a < 0.05 p and adjusted odds ratio with a 95% CI was computed to evaluate the strength of associations.

Results

The prevalence of respiratory symptoms among exposed workers was 27.1% [95% CI (21.7, 32.1)] and 8.3% [95% CI (5.3, 11.6)] among unexposed workers in the previous 12 months and the prevalence was significantly different (X² = 36.82; p < 0. 00001). The odds of developing respiratory symptoms was 3.37 times higher among tannery workers than unexposed workers [AOR: 3.37; 95% CI (1.71, 6.46)]. Female sex [AOR:1.80; 95% CI (1.24, 3.34)], temporarily workers [AOR = 3.43; 95% CI (2.63, 7.95)], working in a poorly ventilated working unit [AOR = 1.88; 95% CI (1.22, 3.98)], absence of occupational health and safety training [AOR = 2.37; 95% CI (1.14, 4.92)], and not using personal protective equipment [AOR = 2.30; 95% CI (1.25, 3.46)] were significant factors.

Conclusion

The prevalence of respiratory symptoms was higher among exposed workers compared to unexposed ones. Sex, employment status, ventilation of working units, absence of occupational health and safety training, and not using personal protective equipment were the factors associated with occupational-related respiratory symptoms. Strategies targeting health and safety training, creating awareness on the use of personal protective equipment, and improving workplace conditions, like the provision of adequate ventilation are useful means for assuaging the condition.

Elemental distribution of metals in urban river sediments near an industrial effluent source

To study the compositional trends associated with the spatial and layer wise distribution of heavy metals as well as the sediment response towards the untreated chemical wastes, we have analyzed river (Buriganga, Bangladesh) sediments by instrumental neutron activation analysis (INAA) and energy dispersive X-ray fluorescence (EDXRF). In nine sediment samples 27 elements were determined where Na, Al, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Zn, As, Rb, Cs, La, Ce, Sm, Dy, Hf, Th and U were determined by INAA and Cu, Sr, Ba, Hg and Pb were determined by EDXRF. Pollution level and the origin of pollutants were evaluated by the aid of geo-accumulation index (Igeo), enrichment factor (EF), pollution load index (PLI) and the inter-element correlation analysis. Major elements are somehow buffered even though the pollution level is severe while the trace metals seem to be highly responsive. Among the heavy metals, Cr is the dominant pollutant, though the pollution level varies systematically with the sampling depth and the distance from the contamination source. Positive linear correlation between Cr and Zn (0.94) ensures the similar anthropogenic source(s) for these two metals, but the sediments of this study respond differently depending upon their geochemical behavior. Rare earth elements (here La, Ce, Sm and Dy), Th and U seem to have crustal origin and the Th/U ratio varies from 2.58 to 4.96.

Consumption of unsafe food in the adjacent area of Hazaribag tannery campus and Buriganga River embankments of Bangladesh: heavy metal contamination

The concentrations of Cr, Cd, Pb, Hg, and As in water, poultry meat, fish, vegetables, and rice plants obtained from the area adjacent to the Hazaribag tannery campus, Dhaka, Bangladesh, were estimated and compared with permissible levels established by the WHO and FAO and levels reported previously by other authors. The metal contents were in the following order according to the concentration in contaminated irrigation water: Cr > Pb > As > Hg > Cd. Mean concentrations of Cr, Pb, Hg, and As in irrigated water were above the permissible levels, whereas the results were below the permissible levels for Cd. The metal concentrations in poultry meat, fish, rice, and vegetables were in the following orders: Pb > Cr > Cd > Hg > As, Pb > Cr > Cd > As > Hg, Pb > As, and Cr > Pb > Cd > As > Hg, respectively. The mean concentrations of metals in poultry meat, fish, rice, and vegetables were much higher than the permissible levels. The trends of weekly intake of heavy metals (WIMs) from poultry meat, fish, rice, and vegetables were as follows: Pb > Cr > Cd > Hg > As, Pb > Cr > Cd > As > Hg, Pb > As, and Cr > Pb > Cd > As > Hg, respectively. WIMs for all the metals were lower than the provisional maximum weekly intake recommended by WHO/FAO and USNAS.

Contamination status and health risk assessment of trace elements in foodstuffs collected from the Buriganga River embankments, Dhaka, Bangladesh

Background

Unsafe food consumption is a severe problem because of heavy metal contamination, which is caused by director indirect activities of industries. The present study was conducted to assess the risk of human health by Heavy metals (Cu, Co, Fe, Zn and Mn) through the intake of vegetables and fishes obtained from the area adjacent to the Hazaribag tannery campus, Dhaka, Bangladesh.

Result

The trend of mean metal concentration in Buriganga river water was Fe >Mn > Zn > Cu > Co and according to Department of Environment, Dhaka Bangladesh (DoE) (1999) the value of the above metals are within the permissible limit of irrigation water except Fe. An assessment of risk involved due to consumption of contaminated food also calculated. The trend of metals in vegetables was Fe > Mn > Zn > Cu > Co and in fishes the trend was Fe > Zn >Mn > Co > Cu. Accumulation of trace elements in vegetables was lower than maximum tolerable levels proposed by FAO/WHO food standard programme (2001) with the exception of Fe and Co respectively. In fishes metal concentration was lower than safe limit set by WHO (1989) except Mn. The Metal Pollution Index (MPI) for all the foodstuffs showed a higher value, however the calculated Health Risk Index (HRI) indicated no risk to human health upon consumption of those foodstuffs.

Conclusion

The overall study suggests that foodstuff in the area were contaminated by the assayed metals and long-term consumption can cause potential health risks to consumers.