Heavy Metals in Vegetables and Fruits

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PROJECT REPORTON

HEAVY METALS IN VEGETABLES AND

FRUITS; AND RISK ASSESSMENT :

LITERATURE REVIEW

SUBMITTED TO SUBMITTED BY

DR. SIBY JOHN ABHISHEK KOUL

PROFESSOR 13201001

ENVIRONMENTAL ENGG M.E ENVIRONMENTAL ENGG


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List of Contents

Topic Page No.

1. Introduction ........................................................................12. Materials and Methods........................................................2

2.1 Selection of Sampling area and sampling........................22.2 Sample Preparation.........................................................22.3 Digestion of Samples.......................................................2

3. Analysis of Heay Metals......................................................33.1 Atomic Absorption Spectrometry....................................33.2 Data Analysis....................................................................5

!. Per"issi#le Li"its for heay "etals and effects.....................$4.1 Limits for heavy metals in food stffs..............................54.2 !ealth effects of heavy metals........................................."

5. Case %tudies..........................................................................&'eferences............................................................................12


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1.IntroductionVegetables and fruits consumption account for the natural uptake of vitamins, minerals,

fibres, etc in humans. These are sources of essential nutrients and antioxidants and as such

act as neutralizing agents for acidic substances formed during digestion.

Environmental pollution is now-a-das a cause of concern. !eav metal pollution of

agricultural soil and vegetables is one of the most severe ecological problems on a world

scale. The food chain contamination is the ma"or pathwa of heav metal exposure for

humans. #ome trace metals are essential in plant nutrition, but plants grown in the nearb

zone of industrial areas displa increased concentration of heav metals. Vegetables and

fruits act as $small accumulators% of different heav metals as a function of soil&air&water

pollution degree.

'apid and unorganized industrialization and urbanisation have contributed to the elevatedlevels of heav metals in the urban environment in the developing countries. !eav metals

are non-biodegradable and persistent environmental contaminants which ma be deposited

on the surfaces and then absorbed into the tissues of the vegetables. Emissions of heav

metals from the industries and vehicles ma be deposited on the vegetable surfaces during

their production, transport and marketing. (lants take up heav metals b absorbing them

from deposits on the parts of the plants exposed to the air from polluted environment as

well as from contaminated soils. )ater contamination b heav metals in some areas is

practicall inevitable due to natural process *weathering of rocks+ and anthropogenic

activities *industrial, agricultural and domestic effluents+. These elements, at concentrations

exceeding the phsiological demands of vegetables, not onl could administer toxic effect in

them but also could enter food chains, get biomagnified and pose a potential threat to

human health. !eav metal contamination in agricultural soils from waste water irrigation is

of serious concern due to its implications on human health. Enormous volumes of

wastewater are being released, which is increasingl being utilized as a valuable resource for

irrigation in urban and peri-urban agriculture. t drives significant economic activit,

supports countless livelihoods particularl those of poor farmers, and substantiall changes

the water ualit of natural water bodies. )aste water from industries of mining,

electroplating, paint or chemical laboratories often contains concentrations of heav metals,

including n, /u, (b, 0n, i, /r, /d. /ontinuous irrigation of agricultural land with sewage

and industrial waste water ma cause heav metal accumulation in soil and vegetables.

(rolonged consumption of unsafe concentrations of heav metals through foodstuffs ma

lead to chronic accumulation of heav metals in various organs of humans such as kidnes

and liver, causing disruption of numerous biochemical processes, leading to cardiovascular,

nervous, kidne and bone diseases. #ome heav metals such as /u, n, 0n, /o and 0o act

as micronutrients for the growth of animals and human beings when present in trace

uantities, whereas others such as /d, 2s and /r act as carcinogens, and !g and (b are


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associated with development of abnormalities in children. 2lso long term intake of /d is

reported to cause renal, prostate and ovarian cancers.

2.Materials and Methods2.1 Selection of sampling area and sampling2 particular area is selected for which sampling is to be done. The area might be in the

vicinit of the industrial effluent dumping site or an other area prone to the heav metals in

the form of pollution from various sources. The samples of vegetables are collected from the

agricultural area or can be randoml purchased from the market in the vicinit. 4ifferent

tpes of vegetable samples are to be collected in which the heav metals concentration is to

be determined.

#oil samples are also to be collected b digging out from the )astewater rrigated *))+

sites. t should be air dried, crushed and stored at ambient temperature before analsis.

2lso the water used for the irrigation purpose is collected, conc. !56 added to avoidmicrobial activit. The samples are then kept in refrigerator before digestion. #amples of soil

and water from /lean )ater rrigated */)+ sites are also taken in order to determine the

Enrichment 7actor.

2.2 Sample PreparationThe vegetables are first washed with distilled water to remove the dust and dirt particles

over the surface. Edible portions are first separated and then cut into small pieces. t is then

weighed to determine fresh weight and the oven dried at a temperature of about 89 :/ for a

certain period of time. The dr samples are then crushed using a mortar or a stainless steelblender and passed through a 3mm mesh size sieve. The resulting fine powder is kept a

room temperature before analsis.

The soil samples are also air dried, crushed and passed through 3mm mesh size sieve and

stored at room temperature before analsis.

2.3 Digestion of samples2.3.1Soil and plant samples#oil and plant samples *1 g+ are to be digested b adding 1; ml of tri-acid mixture of !3#5


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3.Analysis of heavy metals/oncentrations of heav metals in the filtrate of the digested samples can be estimated

using the 2tomic 2bsorption #pectrophotometer.

3.1Atomic Absorption Spectrometry2tomic absorption spectrometr *22#+ is an analtical techniue for uantitative

determination of the chemical elements. n analtical chemistr, the techniue is used for

determining the concentration of a particular element in a sample to be analzed. 2tomic

absorption is so sensitive that it can measure down to parts per billion of a gram in a sample.

The techniue makes use of the wavelengths of light specificall absorbed b the element.

The correspond to the energies needed to promote electrons from one energ level to

another, higher, energ level.

6.1.1 Working Procedure2toms of different elements absorb characteristic wavelengths of light. 2nalsing a sample

to see if it contains a particular element means using light from that element. 7or example

with lead, a lamp containing lead emits light from excited lead atoms that produce the right

mix of wavelengths to be absorbed b an lead atoms from the sample. n 22#, the sample

is atomised = i.e converted into ground state free atoms in the vapour state = and a beam of

electromagnetic radiation emitted from excited lead atoms is passed through the vaporised

sample. #ome of the radiation is absorbed b the lead atoms in the sample. The greater the

number of atoms there is in the vapour, the more radiation is absorbed. The amount of light

absorbed is proportional to the number of lead atoms. 2 calibration curve is constructed b

running several samples of known lead concentration under the same conditions as the

unknown. The amount the standard absorbs is compared with the calibration curve and this

enables the calculation of the lead concentration in the unknown sample.

3.1.2 Te !igt SourceThe common source of light is a $hollow cathode lamp%. This contains a tungsten anode and

a clindrical hollow cathode made of the element to be determined. These are sealed in a

glass tube filled with an inert gas, e.g neon or argon, at a pressure of between 1 m=3

and ;

m=3

. The ionisation of some gas atoms occurs b appling a potential difference of about

699=


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3.2 Data Analysis3.2.1)nricment #actorTo examine the translocation of heav metals from the soil to the edible portion of test

plants, and to show the difference in metal concentrations in the plants between the sites,

the enrichment factor *E7+ can be calculated b using the formula,

E7 ? */oncentration of metal in edible part at )) site&concentration of metal in soil at

)) site+ & */oncentration of metal in edible part at /) site&concentration of metal in

soil at /) site+

!igher values of enrichment factor *E7+ suggest poor retention of metals in soil and more

translocation in plants.

3.2.2*ealt +isk assessment and daily intake of ea,y metals2n assessment of the health risk posed in human beings b the consumption of

contaminated vegetables can be made b comparing the concentration of the contaminants

with national and international safe limits. The dail intake of heav metals through theconsumption of the vegetables tested can be calculated according to the given euation

4ail intake of heav metals *@g&da+ ? */metalA 4food intake+ & Baverage weightwhere /metal, 4food intakeandBaverage weight represent the heav metal concentrations

in plants *@g&g+, dail intake of vegetables and average bod weight, respectivel.

!ealth 'isk ndex

The health risk index can be calculated as the ratio of estimated exposure of test crops and

oral reference dose. Estimated exposure is obtained b dividing dail intake of heav metals

b their safe limits. 2n index more than 1 is considered as not safe for human health.

4.Permissible Limits of Heavy metals and their effects$.1 !imits for some of te ea,y metals in some food stuffs areC


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$.2 *ealt effects of ea,y metals

2rsenic

ower level exposure can cause nausea and vomiting, decreased production of red andwhite blood cells, abnormal heart rhthm, damage to blood vessels, and a sensation of

Fpins and needlesG in hands and feet.

ngestion of ver high levels can possibl result in death. ong-term low level exposure can cause a darkening of the skin and the appearance of

small FcornsG or FwartsG on the palms, soles, and torso.

/admium

ngesting ver high levels severel irritates the stomach, leading to vomiting anddiarrhoea.

ong-term exposure to lower levels leads to a build up in the kidnes and possible kidnedisease, lung damage, and fragile bones.

/hromium

Breathing high levels can cause irritation to the lining of the nose, nose ulcers, runnnose, and breathing problems, such as asthma, cough, shortness of breath, or wheezing.

#kin contact can cause skin ulcers. 2llergic reactions consisting of severe redness andswelling of the skin have been noted.

ong term exposure can cause damage to liver, kidne circulator and nerve tissues, aswell as skin irritation.

ead

Exposure to high lead levels can severel damage the brain and kidnes and ultimatelcause death

n pregnant women, high levels of exposure to lead ma cause miscarriage. !igh level exposure in men and women can cause reproductive problems.0ercur

The nervous sstem is ver sensitive to all forms of mercur. Exposure to high levels can permanentl damage the brain, kidnes, and developing

foetuses. Effects on brain functioning ma result in irritabilit, shness, tremors, changes

in vision or hearing, and memor problems.

#hort-term exposure to high levels of metallic mercur vapours ma cause lung damage,nausea, vomiting, diarrhoea, increases in blood pressure or heart rate, skin rashes, and

ee irritation.

#elenium

#hort-term oral exposure to high concentrations can cause nausea, vomiting, anddiarrhoea.

/hronic oral exposure to high concentrations can cause #elenosis. 0a"or signs ofselenosis are hair loss, nail brittleness, and neurological abnormalities.

Brief exposures to high levels in air can result in respirator tract irritation, bronchitis,difficult breathing, and stomach pains. onger-term exposure can cause respirator

irritation, bronchial spasms, and coughing.


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#ilver

Exposure to high levels for a long period ma result in a condition called 2rgria, a blue-gra discoloration of the skin and other bod tissues. 2rgria appears to be a cosmetic

problem that ma not be otherwise harmful to health.

Exposure to high levels of silver in the air has resulted in breathing problems, lung andthroat irritation, and stomach pains.

#kin contact with silver can cause mild allergic reactions such as rash, swelling, andinflammation in some people.

5.ase !tudies%.1 *ealt risk assessment of ea,y metals ,ia dietary intake of foodstuffs from te

-aste-ater irrigated site at aranasi

ocationC 2round 4inapur sewage treatment plant *4#T(+ situated at a suburban area in the

north east of Varanasi cit in eastern Iangetic plains of ndia during 0arch 399D to 7ebruar

399H.

2 large area around 4#T( has no access to clean water resources, so farmers use treated

and untreated wastewater for irrigation. #oil and water samples were collected at

fortnightl interval from 0arch 399D to 7ebruar 399H. 2ll the ma"or vegetables and cereal

crops grown in the experimental area, either for home consumption or sale, were collected.

2nalsisC /oncentrations of /d, /u, (b, n, i and /r in the filtrate of digested samples were

estimated b using an atomic absorption spectrophotometer. The instrument was fitted

with specific lamp of particular metal and calibrated using manuall prepared standardsolution of respective heav metals.

'esultsC

The range and mean concentrations *@g&g+ of heav metals in soil of wastewater *))+ and

clean water irrigated */)+ sites.


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Enrichment factor of heav metals in collected foodstuffs from the experimental site

nf? not found

!ealth risk index *!'+ of heav metals via intake of foodstuffs from wastewater irrigated

sites

/onclusionsC The health risk index of heav metals suggest that /d, (b and i contamination

in most of the test plants had potential for human health risk due to consumption of plants

grown at waste water irrigated site. 0ilk is found to be least contaminated b heav metals

as its health risk index was lower compared to other foodstuffs. The health risk index of

cereals was higher than vegetables due to higher proportion of cereals in the diet.

/onsumption of foodstuff with elevated levels of heav metals ma lead to high level of

accumulation in the bod causing related health disorders. The stud suggests that even


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though there are low concentrations of heav metals in irrigation water, its long term use

caused heav metal contamination leading to health risk of consumers.

%.2 *ea,y metals concentrations in ,egetables gro-n near dumpsite in Tan/ania

ocationC n the cultivation sites in the vicinit of the closed 0toni dumpsite *< km from the

cit centre+ 4ar es #alaam, Tanzania, during 7ebruar 3911 to Kul 3911.

The dumpsite was receiving waste from the three 0unicipalities of lala, Temeke and

Linondoni, and an average of 899-1399 tonnes of different waste materials were disposed

off at the site dail. The dumpsite was untimel closed in Kanuar 399H due to the

manifested serious environmental implications. Based on the surve, it was found that the

current soil used for cultivation is the land reclaimed from the ocean gulf through crude

dumping of waste materials. The green vegetables Amarantus blitum, &ucurbita ma0ima

*pumpkin leaves+, Ipomea batata, igna unguiculata *cowpea leaves+ and Solanum nigram

are the most grown vegetables in the site.2nalsisC The dr ashing method was used followed b atomic absorption

spectrophotometric analsis. 7or analtical ualit assurance, after ever five sample

readings, standards were run to make sure that the margin of error is within ;M. The

detection limit was 9.91 ppm, slit width 9.H9 nm and elements wavelength were 338.8,

6;H.J, 63


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. unguiculata and S.nigram indicate that the area is not suitable for vegetables production

and animal keeping.

%.3 *ea,y metal status in soil and ,egetables in urban areas of Allaabad

ocationC The current stud was carried out in the around 2llahabad industrial processingzone *2(+, at aini located in 2llahabad district, Nttar (radesh, ndia from 4ecember 3913

to Kune 3916.The stud area is situated in the south side of the river Ianga J km south of 2llahabad cit.

aini 2llahabad municipalit has a conventional sewage treatment plant and final treated

effluent from the treatment plant is directl taken to the ad"oining agricultural land. The

common vegetable grown in the stud area is tomato, spinach, coriander, radish, cabbage

etc. which are supplied to the all vegetables market in 2llahabad and the rest entire the

common market.

2nalsisC #amples of soils and vegetables were collected randoml in triplicate from

effluent-contaminated agricultural land. 2fter digesting, heav metal concentrations of

wastewater, soil and vegetable samples were estimated b atomic absorption spectrometer.

'esultsC

!eav metal concentrations *mg&+ in wastewater used for irrigation

/oncentration of heav metals in wastewater irrigated soil *mg&kg dr soil+


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!eav metal concentration *mg&kg dr weight+ in vegetables grown in waste-water irrigated

agricultural landC 0ean and *'ange+

Bioconcentration 7actor&Enrichment factor of the stud area

/onclusionsC 7rom the results of the present stud it is clear that the elevated level of metal

accumulation in edible parts of vegetable plants is mainl from their growth habitat like

water and soil in and around industrial areas of aini 2llahabad. ong term consumption of

these metal-contaminated vegetables can cause different disease like Brain and Lidne

damage, cancer in human bod, dermatitis. The data generated must be used as baseline

wastewater ualit framework to serve as a basis for monitoring irrigation water ualit in

rurban areas of 2llahabad to ensure safet. 'esponsible agencies should carr out public

health education within the consumption area to sensitive the general public on the

potential effects of indiscriminate disposal of waste and the potential health hazardsassociated with the consumption of vegetables cultivated with wastewater. 0easures must

be taken to reduce heav metal pollution and nutrient loading of irrigation water and soils

to protect the safet of both farmers and consumers.


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"eferences

#ingh, 2nita., #harma, 'L., 2grawal, 0., 0arshall, 70.*3919+. !ealth risk assessment ofheav metals via dietar intake of foodstuffs from the wastewater irrigated site of a dr

tropical area of ndia. 7ood and /hemical Toxicolog

Heavy Metals in Vegetables and Fruits

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