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Year : 2022  |  Volume : 66  |  Issue : 1  |  Page : 27-32  

A real-time investigation on public health consequences of chromium laden effluent from the leather industries

1 PhD Scholar, Department of Bio-Medical Sciences, School of Bio Sciences and Technology, Vellore, Tamil Nadu, India
2 Associate Professor, Department of Bio-Medical Sciences, School of Bio Sciences and Technology; Research Officer, CO2 Research and Green Technology Centre, VIT, Vellore, Tamil Nadu, India

Date of Submission10-Jul-2021
Date of Decision08-Jan-2022
Date of Acceptance14-Jan-2022
Date of Web Publication5-Apr-2022

Correspondence Address:
Anand Prem Rajan
Department of Biomedical Sciences, School of BioSciences and Technology, VIT, Vellore - 632 014, Tamil Nadu
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijph.ijph_1511_21

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Background: Extensive evidence of elevated chromium (Cr) in the surface and groundwater exists. However, the importance of exposure toward Cr-associated health risks in areas with tanneries is still often neglected. These situations prompted an independent research study to investigate the views of those close-knit communities who are being directly affected by this tannery village. Objectives: To establish an understanding of the local demographics and; exploratory data analysis (EDA) to discover patterns in the occurrence of diseases; measure the awareness of residents of the presence of Cr and its harmful health effects. Methods: The EDA technique was used to conduct survey studies on data to uncover patterns, identify anomalies, test hypotheses, and validate assumptions using summary statistics and graphical representations. Results: Out of 14 diseases directly linked to high Cr toxicity, the study reported high levels of diarrhea, epigastric pain, and moderate-to-severe cases of vertigo among those aged more than 22 years. With over 90 active tanneries and toxic Cr released to the environment in a town of <78 km2 area (1.2 tannery/km), there are only 15 hospitals (0.2 hospitals/km) for the population currently accommodating more than a quarter-million people daily (3205 people/km). Conclusion: New mitigation strategies must be put forth to alleviate the negative impacts of the tanneries on the residents and nature most affected as well as the population as a whole.

Keywords: Bioremediation, chromium, tannery, wastewater

How to cite this article:
John R, Rajan AP. A real-time investigation on public health consequences of chromium laden effluent from the leather industries. Indian J Public Health 2022;66:27-32

How to cite this URL:
John R, Rajan AP. A real-time investigation on public health consequences of chromium laden effluent from the leather industries. Indian J Public Health [serial online] 2022 [cited 2022 Aug 16];66:27-32. Available from:

   Introduction Top

The district of Ranipet in the state of Tamil Nadu, India was established by dividing the Vellore district into three parts on November 28, 2019.[1] It is about 20 km from the center of the town of Vellore and is a major industrial hub of southern India.[2] The town is on the northern bank of the Palar river and acts as a major transportation node with a population of 50,764 (2011 census) and currently accommodates more than a quarter-million people daily.[3] There are several large-and medium-scale leather industries making both finished leather and leather articles such as shoes and garments ready for export.[4] Other small industries in Ranipet manufacture chemicals and leather products.[5],[6]

The Palar river is dried up and with no fertile land left behind, the very lifeline of this town is costing the lives of many.[7] These prevailing situations prompted an independent research study proposed to investigate the views of those close-knit communities who are being directly affected by this tannery village.[8],[9]

The purpose of this study was to assess health and socioeconomic impacts on the residents of the area that is undergoing substantive disruption with the excessive tanneries and pollutions caused by them.[10],[11],[12] Data collection was done in the form of a survey.[13] The reason for using a survey is that in the absence of more direct measures, it will be an indirect measure for the variables investigated.[14] The survey attempted to quantify and qualify these impacts, which could then be presented to a Central Pollution Control Board (CPCB) for the scope of development of the people of Ranipet.[15]

The overall mandate of the study was to gain an understanding of the residents of the Ranipet area to assess their perceptions of the anticipated impacts of the increasing number of leather industries.[16],[17] The questions contained in this survey seek to capture quantitative and qualitative data.[18] Likert scales have been used to elicit the perception of the residents.[19] The main objectives of the survey were to: establish an understanding of the local demographics; exploratory data analysis to discover patterns in the occurrence of diseases; measure the awareness of residents of the presence of chromium (Cr) and its harmful health effects.[20],[21]

   Materials and Methods Top

Study area

The survey was conducted in Ranipet town, sub-district Ranipet, district Vellore of Tamil Nadu, India. The sample households were contacted both online and offline, which took place from January 2020 to March 2020. The e-questionnaire was distributed via social media and VIT E-mail service whereas and the handout questionnaires were distributed at the clinics and houses by the volunteers.

Survey content

The survey itself is composed of a mixture of questions using nominal, ordinal and interval variables. Many questions used a Likert scale. Some questions typically applied a 10-point scale measuring the attitude of respondents toward a statement.[22] While other questions applied different scales of quality, such as “very good” to “very bad.” All questions were accompanied by a rationale to remind the survey group of their reasoning and the information that was to be obtained by asking that question. The survey was reviewed multiple times with the aid of experts before the final draft was constructed. The final survey was sent to our expert group to obtain peer review. All necessary corrections were made and the process of passing the survey through the ethics committee. To complete the ethics approval process, a detailed description of the methods regarding the survey administration and procedures were provided. The volunteers were directed to always ask for verbal consent preceding the interviews from the residents of the Ranipet.

Only members of the survey team administered the survey. The pilot study was conducted for 14 days followed by the survey conducted over a span of 2 months.

Survey administration

Multiple internal documents facilitated tracking and allowed for greater ease during the survey process for its managers and its volunteers. The volunteers were coupled into teams of both Tamil- and English-speaking members. Survey interviews were conducted in the afternoon period and halted as soon as the sun went down. Since the volunteers had an uneven sex ratio, it was impossible to group teams into male and female partners at all times.

The participants recorded all the homes that they approached and indicated whether the residents were home, refused to take the survey, or took the survey. After every survey session, a member of the survey team would enter all this information into a master “data log.” This log was updated regularly to ensure that participants were not sent to the same home twice. This was essential to avoid survey duplications as well as to not readdress the residents that had already refused to participate in the survey process. Every survey had an identification number and also tracked which student conducted which survey interview on what date. Therefore, there was a method to track who took the information in case there were questions or complications regarding the survey interviews.

Conducting the survey

The survey team proceeded with a systematic sample targeting the entire area of Ranipet town. The survey interviews took place over 2 months, excluding the respondents of the pilot study. The interviewers were told where to start their surveying for the day and to read and sign the instructions before starting an interview. The interviews were conducted systematically by knocking on every door, on average twice. The sample size was calculated from (Equations 1 and 2).[23]

Where n is the unlimited population, n' is the finite population, z is the z-score, p̂ is the sample proportion N is the population size, ε is the margin of error. The sample size was calculated to be 381.275. A total of 82 e-responses was received and out of 400 handouts, a total of 300 responses were received, leading to a final combined response of 382.

Data entry and quality assurance

Data entry was carried out by the members of the survey team. To ensure that there was no error in the data, we performed a series of steps. The first step was to visually scan all the data entered to make sure that the parameters entered matched with the possible replies. After this, we wanted to see if there was any error entered within potential parameters. That is if the possible replies are numbers from 1 to 10 and the number recorded is a 13 when it should be a 10. To test this, we selected surveys randomly and revisited every entry to ensure that it was entered correctly. We tested 10% of our surveys (382 total surveys therefore we tested 38). To obtain random numbers we used the Microsoft Excel function to obtain numbers between 1 and 382 (=RAND() *382).

To manage and effectively target the outlined objectives, the questions were ranked on a scale of one to five where one represented questions of low concern and five questions of high importance. These questions of high importance are from now on referred to as the “five-star questions;” the ranking of the questions is outlined in Appendix SA.

Influence matrix

During the construction of the survey questionnaire and their associated rationales, we assumed that some of the questions would have some influence on one another.[24] A matrix of influence was performed to close the predominant variables.[25] The perceived influence of each of the 23 questions on another was evaluated, ranging from 1 to 5, where 1 defined a very weak influence and 5 represented a very strong influence. Active elements have a high quotient (Q) value, with a small Q value for passive elements. Sensitive elements have a high product (P) value and a small P-value for inert elements. The resulting matrix is shown in Appendix SB. The pilot study conducted for 14 days indicated that the survey was too long and had an awkward flow. The primary goal was to shorten the survey and reduce redundant questions. The postpilot changes addressed the length and format of the survey. The minor alterations and removal of questions allowed for quicker and more effective use by the volunteers. Once a final version was acquired [Appendix SC], the survey and informative content were all translated into Tamil for ease of understanding for the local people.

   Results Top

General outcomes

The following section is a presentation of key results. All pivot charts are presented in [Figure 1], [Figure 2], [Figure 3], [Figure 4] and Supplementary [Figure S1] and [Figure S2]. Not all survey questions required the creation of histograms, and therefore are not represented.
Figure 1: Tap water rating (Scale1-10).

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Figure 2: (a) Familiarity with chromium contamination in water, (b) Effect of tanneries on health and environment.

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Figure 3: Disease occurrence relation to sources of drinking water.

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Figure 4: Major diseases associated with chromium toxicity.

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The age demographic in the conducted survey was 83% were above 22, 14% were 18–22, and 3% were under the age of 18. The education demographic showed 32% diploma holders, 24% postgraduate, 20% had a bachelor's degree, 15% intermediate, 8% high school, and 1% elementary. Sex demographic showed 55% males, 44% females while only 1% constituted the others.

57.33% of the population has access to piped supply and/or reverse osmosis (RO) water cans, 18.85% has access to public taps and RO water cans, 11.78% has access to bore well and RO water cans, another 11.78% has access only to RO water cans and a 0.26% of the population has access to wells and RO water cans. Despite available sources, the population has the following trend in the use of the source available. About 51% uses the supply pipe, 19% uses RO water cans, 17% uses bore wells and 135 uses public taps.

Around 50% of the population is spending ₹11–₹50 ($0.15–$0.67) per head per week, 27% spending ₹51–₹100 ($0.69–$1.35) per head per week, 15% spending ₹101–₹200 ($1.36–$2.69) per head per week, 3% spending ₹401–₹800 ($5.40–$10.77) per head per week, 2% spending ₹201–₹400 ($2.70–$5.38) per head per week, 2% spending <₹10 ($0.13) per head per week and a 1% spending more than ₹801 ($10.78) per head per week.

Individuals smoking more than 11 cigarettes per day were not included in questions related to health issues as it would have affected the health concerns data being recorded for finding relation to Cr toxicity. The results revealed 95% of the population did not smoke, 3% smoked 1–5 cigarettes per day, 1% smoked 6–10 per day, 0% smoked 11–15 cigarettes per day and only 1% smoked more than 15 cigarettes per day.

   Discussion Top

Even though the supply pipe was the most used source of water, it was rated the least on the Likert scale of 10 in terms of taste, smell, colour, clarity, safety, availability and cost [Figure 1].

There was very low awareness about Cr contamination in water and other heavy metals in general. The tanneries are a major source of pollution in the region and the majority of the population is facing some kind of dermatitis [Figure 2].

The difference in water consumption and perceptions was seen in males and females, and also among the different age groups when it came to the suitability of available water [Figure S1], best water source and water quality responsibility [Figure S2], all of which can be correlated to the level of education received.

In terms of disease occurrence related to the source of water used was observed that individuals using supply pipe were highly susceptible to respiratory diseases, epigastric pain, diarrhoea and vertigo. The college-going and working-age female population are found to be more prone to the harmful effects as they are consuming more water frequently when compared to the males of the same age group [Figure 3] and [Figure 4].

   Conclusion Top

The population is majorly relying on tap water supply as a source of drinking water even though the quality is perceived as being very poor. The occurrence of prolonged diseases is seen in people consuming water from the tap water supply. The tannery village is facing serious health problems which can be directly linked to Cr contamination in the water. The study area reported high levels of diarrhea, epigastric pain, and moderate-to-severe cases of vertigo, especially in the over 22 years population, which can be traced to high Cr toxicity. There is very little awareness about the presence of high Cr concentration in the water and its health effects. The population reasons tanneries to be overly contributing to air and water pollution, leading to skin diseases. Some broad conclusions can be drawn by the CPCB in determining if any, mitigation or compensation strategies must be put forth to alleviate the negative impacts of the tanneries on the residents and nature most affected as well as the population as a whole. Once impacts are quantified, these measures can be more successfully derived.

For future considerations, this study design can be broadened. Recommendations stemming from experience with this study include: (a) condensing the survey to facilitate administration by interviewers, (b) holding a preliminary workshop to identify the issues that residents are concerned about, (c) increasing the size of the study area and the sample size to allow for greater variability and higher statistical significance, and finally, (d) including a control group for comparison.


The authors would like to acknowledge the administration, Vellore Institute of Technology, Vellore, for providing vital facilities.

Financial support and sponsorship

The current work was supported by the VIT SEED Grant (SEED-2576), provided by the Vellore Institute of Technology (VIT), Vellore.

Conflicts of interest

There are no conflicts of interest.

   Supplementary Appendices Top

   References Top

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  [Figure 1], [Figure 2], [Figure 3], [Figure 4]


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