profile and associated health risks resulting from untreated tannery wastewater discharges in

Overview

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Key numbers

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Principal Component Analysis (PCA) revealed three principal components that accounted for 85.9% of
6Ministry of Earth Sciences, Government of India, Prithvi Bhawan, Lodhi Rd , New Delhi 110003, India. email:
region experiences 1,100–1,500 mm rainfall, and temperatures in the range 13 °C to 30 °C. The landscape is gently
3050B. The calibration was made with certified standard solutions (1000 mg/L stock) diluted to 0.5–10 mg/L,
calibrated equipments were utilized throughout the study. Reagent blanks, duplicate samples (≥ 10%), and
ranging from 1.2 to 4.7% for major parameters like BOD5, COD, and heavy metals. Reagent blanks validated
extreme departures from the standards established by the NESREA (Table 1), as well as from values reported in
analogous international research8, 10. The color concentration of the effluent ranged from 210 to 370 Pt-Co units,
in terms of color content in the range 250 to 400 Pt-Co units 41,42 respectively. The result is a testimonial to the
in the samples ranged within NESREA’s acceptable limit (1.35–2.30 mg/L), but total solids (TS), which is the
Table 1. Physical analysis of tannery effluent from naraguta, Jos
collective of both suspended and dissolved phases, ranged between 5.00 and 9.10 mg/L. It is a hazard to aquatic
nitrogen (TN), nitrogen (N), sulphur (S), chloride (Cl⁻), total iron (Fe), and total chromium (Cr) (Table 2). All
samples ranged between 7.0 and 7.6, reflecting slightly alkaline to neutral conditions. These values are similar to
pH levels usually ranged from 7.0 to 8.5. The tannery waste from Naraguta has elevated pollutant concentrations
such as BOD (210–300 mg/L), COD (570–720 mg/L), and total nitrogen (38–55 mg/L), which all exceed the
observed in Egyptian tanneries48 which were between 150 and 300 mg/L. Apart from contributing to the
iron (Fe) and total chromium (Cr) ranged from 2.1 to 2.8 mg/L and 2.8 to 3.4 mg/L, respectively. There is an
75 to 90 mg/L. These levels are consistent with findings by51 in Iran, unpleasant smells and the production
collected from Naraguta (Sites A to G) were analyzed (Table 3, & Fig. 3). The potential of the effluent as a
coli levels ranged from 10 to 23 MPN/100 mL, representing contamination levels commonly associated with
Helminth egg levels in Punjab (India), Pakistani tannery wastewater, for example, were found to range from 5 to
Sample pH BOD (mg/L) COD (mg/L) Total Nitrogen (mg/L) N H3 S O4 Ca2+ Cl− N a+ Fe Cr Zn2+
Table 2. Chemical Analysis of Naraguta Tannery Effluent
Table 3. Biological Parameters Analysis of tannery effluent from Naraguta
Sample pH BOD (mg/L) COD (mg/L) TN (mg/L) N H 3 (mg/L) S O 4 (mg/L) Ca2+(mg/L) Cl−(mg/L) N a+ (mg/L) Total Fe Total Cr Zn2+
Table 4. Naraguta effluent pollution index of chemical parameters
resulted in elevated microbial counts41,57. Developed nations such as Spain and Italy had undetectable levels of
consumption (Table 4; Fig. 2). Nevertheless, turbidity was high (PI: 14.40–15.20), reflecting low water clarity
(BOD: 4.20-5.60 mg/L) and Chemical Oxygen Demand (COD: 2.28-2.88) were above limits, which was an index
hazards. Heavy metals, including iron (Fe: 2.1-2.8 mg/L) and chromium (Cr: 5.6-6.8 mg/L), were way above
NESREA limits (Fe: 0.3 mg/L; Cr: 0.05 mg/L), showing extreme environmental threats. In contrast, sodium
(Na⁺) and zinc (Zn²⁺) contents were within tolerable limits (Table 2; Fig. 3). Results from various international
classification (Fig. 4). However, chromium (Cr) was a notable exception, with I_geo value reaching as high as
The calculated Chronic Daily Intake (CDI) of iron (Fe) and chromium (Cr) at seven stations (A–G) (Table 5)
shows definitive spatial trends in exposure. For adult reference, Fe-CDI ranged from 0.0600 to 0.0800 mg/kg/
day, while Cr-CDI varied between 0.0800 and 0.0971 mg/kg/day. In kids values were much greater because of
their lighter body weight and physiological sensitivity with Fe-CDI varying between 0.1400 and 0.1867 mg/kg/
day, and Cr-CDI from 0.1867 to 0.2267 mg/kg/day. These values were above concern thresholds especially for Cr.
Table 5. Chronic Daily Intake (CDI) for Fe and Cr in Naraguta for adults and children
levels of 0.045–0.082 mg/kg/day of Cr-CDI in a leather tannery area in Bangladesh, which shows that the level of
CDI values of 0.05–0.07 mg/kg/day in the vicinity of textile dye effluent points in Pakistan, which are marginally

Methods (brief)

Naraguta area of Jos, Nigeria. A total of 84 surface water samples were collected over a course of one
year. Samples were examined for major physicochemical parameters (like pH, electrical conductivity,
atomic absorption spectrophotometry (AAS), while levels of nutrients (nitrate, sulfate, chloride,
were 3-6 times over permissible levels. Contamination Index (CI) rated samples taken from stations
6Ministry of Earth Sciences, Government of India, Prithvi Bhawan, Lodhi Rd , New Delhi 110003, India. email:
84 surface water samples were collected over one year to assess the spatial and temporal extent of pollutants in
tannery wastewater-polluted environments. Seven samples were collected monthly from seven systematically
dispersion gradients from the point source. At each sampling station, three replicate samples were collected
contamination and guarantee sample integrity for physicochemical, microbial, and heavy metals analysis. All
samples were kept in ice during transport and analyzed within 24 to 48 h of sampling. A systematic fixed-interval
is widely applied in environmental impact assessments for industrial effluents. Monthly samples were taken
provides standard validated procedures for the collection of samples, their preservation, and guidelines to analyse
of the parameters like pH, EC, BOD5, COD, TDS, TSS, nutrients. Microbial Indicators, and Atomic Absorption
Spectrophotometry (AAS) were utilized for heavy metal determination. The used procedures maintained
Monthly, a total of 7 samples were taken and analyzed. Parameters measured were pH, electrical conductivity
(Fe) and chromium (Cr), were measured by atomic absorption spectrophotometry (AAS) after calibration of the
instrument with certified standards. Heavy metals (Fe and Cr) were determined by Flame Atomic Absorption
Spectrophotometry (AAS) by APHA Standard Method 3111 B, and sample digestion according to EPA Method

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The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.

Commit	Date	Change	Description
b01ec52c	2026-08-04	major	2 sections added
d49e450f	2026-08-03	major	5 sections added; narrative text revised