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Course : ACCE-1211

1st Year : Even Semester

Group-B : Chapter-1

Leather

Sunday, October 11, 2015

Course Outline

1. Leather, hides and skins and it’s classification

2. Structure of animal skins

3. Pretannage process, tanning process- vegetable and chrome tanning

4. Finishing of leather and commercial aspects of leather

5. Pollution problems from leather industry

6. Leather industry in Bangladesh


History of Leather

Primitive people who lived during the Ice Age some 500,000 years ago, were likely the first to use

the skins of animals to protect their bodies from the elements. Just as leather today is a

byproduct, our ancient ancestors hunted animals primarily for food, but once they had eaten the

meat, they would clean the skin by scraping off the flesh and then sling it over their shoulders as a

crude form of a coat. They also made footwear to protect their bare feet from rocks and thorns by

taking smaller pieces of animal skin


Animal SkinThe skin is the largest organ of the body. It provides a protective barrier

against the environment, regulates temperature, and gives sense of touch.

Depending on the species and age, the skin may be 12 to 24% of an animal's

body weight.

The skin has 3 major layers:

1. The epidermis or outermost layer,

2. The dermis or middle layer, and

3. The subcutis or innermost layer.

Other important components include skin appendages (such as hair and

hooves), and subcutaneous muscles and fat.


Source: E-books

Structure of Animal Skin


Source: E-books


1. The epidermis is composed of the outermost layers of the skin. It forms a protective barrier over the

body's surface, responsible for keeping water in the body and preventing pathogens from entering.

The epidermis also helps the skin regulate body temperature.

2. The dermis is the layer of skin below the epidermis that consists of connective tissue and pillows the body

from stress and strain. The dermis provides tensile strength and elasticity to the skin through

an extracellular matrix composed of collagen fibrils, microfibrils, and elastic fibers.

3. The hypodermis is not part of the skin, and lies below the dermis. Its purpose is to attach the skin to

underlying bone and muscle as well as supplying it with blood vessels and nerves. It consists of

loose connective tissue and elastin.


Source: E-books



Source: E-books

Hide, Skin & Kip

Skin: Small animal such as, goat, sheep, calf or baby cow etc. the skin of these

types of animal are directly called skin.

Kip: The skin of medium size of animal is called kip. Example- wild fox, dog,

Dear animal etc.

Hide: The skin of big or large size of animal such as, steer of cow, bull, horse,

buffalo etc. These types of animal skin are directly called hide.


Source: Industrial Chemistry-By B.K. Sharma

According to leather size, they are classified into three categories:

Composition of Skin & HideSL NO. Item Composition Type

1 Water 60 to 70%Free Water and

Bound Water

2 Protein 19.2 to 32.75%

Fibrous Protein (Karotine, Collagen, Elastin and

Raticuline)

Non-fibrous Protein (Albumine, Globutin and

Mucin)

3 Fats and Oils 1.5 to 12.25%Non-Glyceride and

Saturated Glyceride of Fatty Acid

4 Mineral 0.36 to 0.5%Chloride, Sulphate, Carbonate salt of

Na, K, Ca, and Mg

5Dye, Charbohydrate,

Enzyme etc.Trace Amount -


Leather

Leather is a durable and flexible material created by the tanning of

animal rawhide and skin, often cattle hide. It can be produced through

manufacturing processes ranging from cottage industry to heavy industry.

Leather is used for various purposes including clothing (e.g. shoes, hats, jackets,

skirts, trousers and belts), bookbinding leather wallpaper, and as a furniture

covering. It is produced in a wide variety of types and styles and is decorated by

a wide range of techniques.


Leather Processing


Tanning Process

Pre - Tanning Tanning Post Tanning1. Vegetable Tanning

2. Chrome Tanning

3. Oil Tanning

4. Wet-white Tanning

1. Skinning

2. Curing

3. Soaking

4. Liming

5. Unhairing and scudding

6. De-liming and bating

7. Pickling

1. Removal of excess water

and tanning liquor

2. Shaving and splitting

3. Neutralizing and coloring

4. Setting out

5. Drying

6. Finishing operations

Pre-Tanning Process

1. Skinning

2. Curing

3. Soaking

4. Liming



7. Pickling


1. Skinning

The actual leather process begins with

the obtaining of an animal skin. When an

animal skin is to be tanned, the beast is

killed and skinned before the body heat

leaves the tissues. This can be done by

the tanner, or by obtaining a skin at a

slaughterhouse or farm.

Pre-Tanning Process


Source: E-books

2. Curing is done by solid salt or salt solution (Brine). In wet-salting, the

hides are heavily salted, then pressed into packs for about 30 days (Salt is

spread between each layer about 1kg/kg of hide). In brine-curing the hides are

agitated in a salt water bath for about 16 hours.

Curing is employed to prevent putrefaction of the protein substance (collagen)

from bacterial growth during the time lag that might occur from procuring the

hide to when it is processed.

Curing removes excess water from the hides and skins using a difference in

osmotic pressure. The moisture content of hides and skins gets greatly

reduced. Generally speaking, curing substantially reduces the chance of

spoilage by bacteria. Curing can also be done by preserving the hides and

skins at a very low temperature.

Pre-Tanning Process


Pre-Tanning Process

Curing


Source: E-books

3. Soaking

The hides are soaked in clean water to remove the salt left over from curing and

increase the moisture so that the hide or skin can be further treated.

Pre-Tanning Process

Sunday, October 11, 2015Source: E-books

4. LimingAfter soaking, the hides and skins are taken for liming: treatment with milk of

lime (a basic agent) that may involve the addition of "sharpening agents" (disulfide

reducing agents) like sodium sulfide, cyanides, amines etc. The objectives of this

operation are mainly to:

• Remove the hairs, nails and other keratinous matter

• Remove some of the interfibrillary soluble proteins like mucins

• Swell up and split up the fibres to the desired extent

• Remove the natural grease and fats to some extent

• Bring the collagen in the hide to a proper condition for satisfactory tannage

Pre-Tanning Process



Unhairing agents used at this time are: Sodium sulfide, sodium hydroxide, sodium hydrosulfite,

calcium hydrosulfide, dimethyl amine, and Sodium sulfhydrate. The majority of hair is then removed

mechanically, initially with a machine and then by hand using a dull knife, a process known

as scudding.

Pre-Tanning Process


The pH of the collagen is brought down to a lower level so that enzymes may act on it, in a

process is known as de-liming. Depending on the end use of the leather, hides may be treated

with enzymes to soften them, a process called bating.


Pre-Tanning Process7. Pickling

Once bating is complete, the hides and skins are treated with a mixture of common

(table) salt and sulfuric acid, in case a mineral tanning is to be done. This is done to bring

down the pH of collagen to a very low level so as to facilitate the penetration of mineral

tanning agent into the substance. This process is known as pickling. The common salt (sodium

chloride) penetrates the hide twice as fast as the acid and checks the ill effect of sudden drop

of pH.


Tanning is the process that converts the protein of the raw hide or skin into a

stable material which will not putrefy and is suitable for a wide variety of end

applications.

The principal difference between raw hides and tanned hides is that raw hides

dry out to form a hard inflexible material that can putrefy when re-wetted

(wetted back), while tanned material dries out to a flexible form that does not

become putrid when wetted back.

Tanning Process


Tanning ProcessTanning refers to the procedure of chemically treating raw hides to make it

stronger, more flexible and resistant to decay.

The tanning process consists in strengthening the protein structure of the

putrescible skin by creating a bond between tannins and peptide chains. The skin

is made up of three layers being the epidermis, dermis and subcutaneous layers.

The dermis consists between 30-35% protein, mostly collagen, and the remaining

are fat and water. It is the dermis that is used to make the leather after the other

layers have been removed chemically or mechanically. During the tanning

process, acids, alkalis, salts, enzymes and tanning agents are used to dissolve the

fats and non-fibrous proteins, as well as chemically bond the collagen fibers with

the tanning agents.


Tanning ProcessTannic acid is a specific commercial form of tannin, a type of polyphenol. Its

weak acidity is due to the numerous phenol groups in the structure. The chemical

formula for commercial tannic acid is often given as C76H52O46 . Commercial tannic acid is

usually extracted from any of the following plant part: Tara pods (Caesalpinia spinosa),

gallnuts from Rhus semialata or Quercus infectoria or Sicilian Sumac leaves (Rhus

coriaria).


Source: E-books

Tanning Process

1. Vegetable Tanning

2. Chrome Tanning

3. Oil Tanning

4. Wet-white Tanning



The oldest system of tanning relies on the chemical action of vegetable material containing tannin,

or tannic acid, on the protein constituents of skin. Vegetable tanning seems to have been practiced

in prehistoric times. In historic times, the Hebrews tanned with oak bark, and the Egyptians, with

babul pods. The Romans used bark, certain woods, and berries. The Arabs tanned with bark and

roots, and in the Middle Ages they reintroduced the art into Europe via Spain. By the 18th century

the value of materials such as oak bark, sumac, valonia, and hemlock was well established. The

procedure, essentially unchanged in modern times, involves soaking hides in vats of increasingly

strong liquors, or liquid extracts of vegetable tannin.

Vegetable tanning


Vegetable tanning

Vegetable tanning uses tannin. The tannins (a class of polyphenol caustic chemical) occur

naturally in the bark and leaves of many plants. Tannins bind to the collagen proteins in the hide

and coat them causing them to become less water-soluble, and more resistant to bacterial attack.

The process also causes the hide to become more flexible. The primary barks, processed in bark

mills and used in modern times are:

chestnut, oak, redoul, tanoak, hemlock, quebracho, mangrove, wattle (acacia; see catechu),

and myrobalan Hides are stretched on frames and immersed for several weeks in vats of

increasing concentrations of tannin. Vegetable tanned hide is flexible and is used for luggage and

furniture.


Vegetable tanning


Vegetable tanningAdvantages of Vegetable tanning:

Colors and textures have a more natural and organic look;

It is irregular and handcrafted which can be leveraged for an unique and genuine aesthetic;

Great durability and strength, being even more effective than the majority of the synthetic

materials;

Neutral effect on the user's health;

Can last an entire lifetime (or more) and/or it is bio-degradable when it ceases to be

used/maintained;

Remarkable and sought-after aging qualities, acquired with the use;

Reusability;

Enhances the animal use as it is obtained from cattle with a good life, and always as a sub-product

of the quality meat industry;

Values slower life and an eco-sustainable industry;

Regenerates the local society and general culture.


Vegetable tanningThere are some disadvantages in using vegetable-tanned leather including:

1. The process of vegetable tanning takes a long time, and can take up to 60 days.

2. Vegetable tanning doesn’t react well with water and can stain easily.

3. Products that have been vegetable tanned are more expensive.

4. The colors you can produce from vegetable tanning are limited.

5. Direct heat can cause vegetable tanned products to shrink or crack.


Chrome tanningToday, 80-90% of leathers in the world are tanned by chrome tanning. Chrome tanning uses a

solution of chemicals, acids and salts (including chromium sulphate) to tan the hide. It’s a very

quick process, taking about a day to produce a piece of tanned leather.

Two methods are used. In the double-bath method the hides are first bathed in a mild

chromic acid solution. In the second bath, sodium thiosulfate and another acid react with the

chromic acid to produce basic chromium salts, which are deposited on the fibers of the skins.

In the more common single-bath method first hide are limed to remove hair and then are

“pickled” by being left in the acid salt mixture, before being placed in the chromium sulphate.

Then hides are soaked in revolving drums filled with increasingly strong chromium sulfate

solutions. Aluminum and zirconium salts are also used in tanning. All hides then come out

looking light blue (known as “wet blue”).



Chrome tanning

Main advantages of chrome tanning

• Quick and easy to produce, usually only taking up to a day

• Water can roll off the surface easily with appropriate retanning and finishing processes

• Soft and supple to the touch

• It is possible to obtain leather with a stable colour

• It is cheaper to buy than vegetable tanned leather, which means it is also easier to find

• It has a high degree of thermal resistance


Chrome tanningDisadvantages of chrome tanning

• Chrome tanning is very bad for the environment

• It’s produced with little craftsmanship and very often mass produced

• It doesn’t wear well with time

• Chrome tanning often smells of chemicals

• It doesn’t appear (neither is it) very natural

• Lacks of charm and hotness


Chemistry of Chrome TanningChromium(III) sulfate ([Cr(H2O)6]2(SO4)3) has long been regarded as the most efficient and effective tanning agent.

Chromium(III) compounds of the sort used in tanning are significantly less toxic than hexavalent chromium.

Chromium(III) sulfate dissolves to give the hexaaquachromium(III) cation, [Cr(H2O)6]3+, which at higher pH

undergoes processes called olation to give polychromium(III) compounds that are active in tanning, being the

cross-linking of the collagen subunits. The chemistry of [Cr(H2O)6]3+ is more complex in the tanning bath rather

than in water due to the presence of a variety of ligands. Some ligands include the sulfate anion, the collagen's

carboxyl groups, amine groups from the side chains of the amino acids, as well as "masking agents." Masking

agents are carboxylic acids, such as acetic acid, used to suppress formation of polychromium(III) chains. Masking

agents allow the tanner to further increase the pH to increase collagen's reactivity without inhibiting the

penetration of the chromium(III) complexes.

Collagen is characterized by a high content of glycine, proline, and hydroxyproline, usually in the repeat -gly-pro-

hypro-gly-. These residues give rise to collagen's helical structure. Collagen's high content of hydroxyproline allows

for significant cross-linking by hydrogen bonding within the helical structure. Ionized carboxyl groups (RCO2-) are

formed by hydrolysis of the collagen by the action of hydroxide. This conversion occurs during the liming process,

before introduction of the tanning agent (chromium salts). The ionized carboxyl groups coordinate as ligands to the

chromium(III) centers of the oxo-hydroxide clusters.

Tanning increases the spacing between protein chains in collagen from 10 to 17 Å. The difference is consistent with

cross-linking by polychromium species, of the sort arising from olation and oxolation.


Chemistry of Chrome Tanning


Vegetable VS Chrome Tanning

SL NO. Vegetable Tanning Chrome Tanning

1 It is processed by Vegetable Extract It is processed by Chromium Compound

2 Low grade leather- used for sole, belt High grade leather-used for bag, cloth

3Pickling operation is not necessary

in the pre-tannage processPickling operation is necessary

4 Water can be penetrated It is water resistant

5It is needed 15-20 days to

complete the tanning processOnly 24-48 hrs. need for processing


Oil Tanning

Oil-tanned leather is not actually tanned with oil – it is usually a chrome-tanned

leather that has been treated with oil to make it more weather resistant.

Oil tanning is an ancient method that is used for such soft, porous leathers as

chamois and deerskin, which can be repeatedly wetted and dried without harmful

effects. Fish oil is scattered onto the hides and pounded in with mechanical

hammers. The hides are then hung in ovens, and the oxidized oil adheres to the

skin fibres.


Oil Tanning


Wet-white tanning

This refers to leather with a pale cream or white color. This fairly new method

of tanning has been gaining popularity, partially due to increased concern for

the environment. Wet white tanned leathers are free of chrome and recyclable.

The main products used for wet white tanning are synthetic tannins, such as

phenolic, disulphonic and naphthalenic products, aldehydes, metals

(Zirconium, Aluminium, etc.).

The tanning based on alum, zirconium, titanium, iron salts or a combination

thereof lead to 'wet white'. Wet white is also a semi finished stage like wet blue,

but is much more eco friendly. The shrinkage temperature of wet white varies

from 70 to 85 degree Celsius, while that of wet blue varies from 95 to 100

degree Celsius.


Wet-white tanning

leather and leather products sometimes contain some hazardous substances

like chromium (VI) although only chromium compounds in the form of

chromium (III) were used in the tanning process. It has been concluded that

the chromium (VI) in the leather is formed by an oxidation of the chromium (III)

added to the leather during the tanning processes.

In order to avoid this issue wet white leathers are produced


Wet-white tanning


Advantages of wet white tanning

• Wet-white leathers are lighter in color and can be converted into pastel shade leathers

• Shrinking temperatures of at least 70°C

• High softness

• Good lightness

• Natural sensation

• Pleasant touch

• Beauty over the time

• High performance leather can be obtained, often better than chrome tanning

• Leather can be burnt without the hazard of chromium (VI) formation

Wet-white tanning


Wet-white tanning

Disadvantages of wet white tanning

• Slightly higher production cost compared to chrome tanning. Newer

techniques have reduced this difference

• Requires more controls compared to chrome tanning


Difference Between Raw & Pure Leather

SL NO.

Raw Leather Pure Leather

1 It is degradable It is not normally degradable

2 It is shrinkable It is not shrinkable

3 It cannot be used It is usable

4 Water can be penetrated through the small pore It water resistant

5 It is used as raw material for pure leather It is used as practical purpose


Finishing of LeatherAfter tanning process, the leather is dried and accumulated in a godown. This leather is called

crush leather. This crushed leather is then treated according to the customer demand. The

treatment process of crush leather is known as finishing of leather. This process involves the

following steps:

1. Removal of excess water and tanning liquor

2. Shaving and splitting


4. Setting out

5. Drying



Finishing of Leather1. Removal of excess water and tanning liquor

The leather contains excess water and tan liquor specially in case of vegetable tanning. The

goods are dipped in vat containing mild tanning liquor which leaches out the uncombined tannin.

The stock is then pressed in a hydraulic press or by passing it through a wringer.

2. Shaving and splittingLeather may be split into layers for making top leathers and glove stock. This is done with the help of a

sharp knife which can penetrate to a desired depth below the grain surface. For light leathers, the leather

is shaved on a shaving machine containing sharp spiral knife blades fitted in revolving cylinder.


The leather is washed in a drum and neutralized with mild alkali and again washed. Then the

stock is dyed in direct dye solution in warm water. In case of vegetable tanned leather, it is

bleached also with oxalic acid or sulfuric acid or formic acid before dying. Hypo may be used to

remove excess acid. Dying is performed in drums about 0.5 to 2.0% basic dye based on the

weight of leather dissolved in warm water being used. The drum is rotated for half an hour and

then little amount of formic acid is added to destroy excess dye.


Finishing of Leather4. Setting out

The leather is set out either by machine or by hand. The machine consists of revolving

cylinders which smoothen the leather and stretch it. As a result the water present in the

leather is squeezed out.

5. DryingChrome leather is covered with saw dust and left for a day or two to remove part of the moisture about

35%. They are staked and dried in tunnel after stretching on frames. After drying the leather is allowed

to stand to attain equilibrium moisture and then stacked and finished. Vegetable tanned leathers are

dried by taking on wooden frames and then stacking in tunnels through which air with controlled

temperature and humidity is passed.


Light leathers are finished by applying pigment coat, plasticizers etc. Chrome leather is glazed

by a machine having rotating glass cylinder. The friction improve the glaze. Vegetable tanned

leather is finished by applying oil to the grain surface and passing it through a heavy roller.

Vegetable tanned leather are given decorative patterns by embossing with a hydraulic press.


Chemicals Used in Leather ProcessingBiocidesBiocides prevent the growth of bacteria which can damage the hides or skins during the soaking process

SurfactantsSurfactants are used to help with the wetting back of the hides or skins

DegreasersDegreasers help with the removal of natural fats and greases from the hides or skins

Swell regulating agentsSwell regulating agents help prevent uneven swelling of the hides or skins during liming

LimeLime is used to swell the hides or skins

Sodium sulphideSodium sulphide chemically destroys the hair on hides or skins

Sodium hydrosulphideSodium hydrosulphide chemically destroys the hair on hides or skins. It does not create as much swelling as sodium sulphide


Chemicals Used in Leather Processing

Low sulphide unhairing agentsLow sulphide unhairing agents help to reduce the amount of sulphides used in a tannery thus reducing

Caustic sodaCaustic soda is used during the liming process to help swell the hides or skins

Soda ashSoda ash is used during the soaking or liming processes to help raise the pH of the hides or skins

Ammonium sulphateAmmonium sulphate is used during the deliming process and helps remove lime from the hides or skins

Ammonium chlorideAmmonium chloride is used during the deliming process and helps remove lime from the hides or skins

Sodium metabisulphiteSodium metabisulphite is used during the deliming process and helps prevent the formation of toxic hydrogen

Formic acid

Formic acid is used during the pickling process to lower the pH of the hides or skins


Chemicals Used in Leather ProcessingSulphuric acidSulphuric acid is used during the pickling process to lower the pH of the hides or skins

SaltSalt is used during the pickling process to prevent acid swelling of the hides or skins

Sodium formateSodium formate is used during the tanning process to assist with the penetration of chromium tanning

salts into the hides or skins

Chromium sulphateChromium sulphate is the tanning agent used to make wet blue

Aldehyde tanning agentsAldehydes are tanning agents used to make wet white

Magnesium oxideMagnesium oxide is used during basification and raises the pH of the hide or skin to allow the chromium

or aldehyde to chemically bind to the skin protein


Several tanning processes transform hides and skins into leather:

Vegetable-tanned leather is tanned using tannins and other ingredients found in different

vegetable matter, such as tree bark prepared in bark mills, wood, leaves, fruits and roots and

other similar sources. Vegetable-tanned leather is not stable in water; it tends to discolor

Chrome-tanned leather, invented in 1858, is tanned using chromium sulfate and other salts

of chromium. It is also known as wet-blue for its color derived from the chromium. More esoteric

colors are possible using chrome tanning.

Aldehyde-tanned leather is tanned using glutaraldehyde or oxazolidine compounds. This is the

leather that most tanners refer to as wet-white leather due to its pale cream or white color. It is

the main type of "chrome-free" leather, often seen in automobiles and shoes for infants.

Types of Leather


Types of LeatherIn general, leather is sold in four forms:

Full-grain leather refers to hides that have not been sanded, buffed, or snuffed (as opposed to top-grain or

corrected leather) to remove imperfections (or natural marks) on the surface of the hide. The grain remains

allowing the fiber strength and durability.

Top-grain leather (the most common type used in high-end leather products) is the second-highest quality. Also

referred to as “Genuine Leather”, top-grain leather has had the top layer removed, which removes the bug bites,

scars, etc., making the grain side more uniform in appearance.

Corrected-grain leather is any leather that has had an artificial grain applied to its surface. The hides used to

create corrected leather do not meet the standards for use in creating vegetable-tanned or aniline leather.

Split leather is leather created from the fibrous part of the hide left once the top-grain of the rawhide has been

separated from the hide. Split leather is what’s left after the top grain of the hide is remove. Depending on the

thickness of the original hide, multiple splits can be cut from the same hide. During the splitting operation, the

top-grain and drop split are separated.


Types of Leather

Full Grain Top Grain

SplitCorrected Grain


Environmental impact

Leather is a product with some environmental impact, most notably due to:

• The use of chemicals in the tanning process (e.g. chromium, formic acid, mercury and

solvents, ...)

• Air pollution due to the transformation process (hydrogen sulfide during dehairing and ammonia

during deliming, solvent vapors).

• Leather biodegrades slowly; it takes 25 to 40 years to decompose. However, vinyl and petro-

chemical derived materials will take 500 or more years to break down and return to the earth.


Environmental impact

One ton of hide or skin generally leads to the production of 20 to 80 M3 of wastewater

including chromium levels of 100–400mg/L, sulfide levels of 200–800mg/L and high

levels of fat and other solid wastes, as well as notable pathogen contamination. Pesticides are

also often added for hide conservation during transport. With solid wastes representing up to

70% of the wet weight of the original hides, the tanning process comes at a considerable

strain on water treatment installations.


Waste discharge from tanneries pollutes the air, soil, and water, causing serious health

problems. Exposure to such contaminated environmental milieu has been seen to culminate in a

multiple array of disease processes such as asthma, dermatitis, hepatic and neurological

disorders, and various malignancies. An overall scarcity of research on the occupational

hazards of employment in the leather industry as well as its effects on pediatric population was

observed.

Health impact


Health Impact

Chromium commonly occurs in two forms. Trivalent chromium (chromium III) is a naturally occurring element that

is relatively stable and innocuous, and can be found in plants, animals, and soil. Hexavalent chromium (chromium

VI) is far more dangerous for humans, and is usually created by anthropogenic causes.

Hexavalent chromium is a toxic human carcinogen that can cause or increase the rates of certain cancers.

Inhalation of chromium VI, which occurs most frequently among workers, has been found to cause cancer of the

respiratory system. Inhalation of dust contaminated with chromium can also lead to eye damage, ulcerations,

swelling, asthmatic bronchitis, and irritation to the throat and nose. More chronic exposure can sometimes

cause sores to develop in the nose and can even lead to the formation of holes in the nasal septum.

Ingestion of chromium VI can cause stomach problems, such as ulcers, and can also be damaging for kidney and

liver functions. Dermal contact causes a number of skin problems, including rashes, sores, and ulcers.

In addition, several studies have found evidence that chromium accumulation in the body can damage a person’s

ability to metabolize iron, which can lead to iron deficiency anemia.


Tannery Pollution


Tannery Pollution


Tannery Pollution


Thank you all


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