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Prevention Measures

STUDIES OF LEAD LEVELS IN THE ENVIRONMENT IN INDIA

Dr. P.K. Seth and Dr. D.K. Saxena

Lead is an ubiquitous environmental pollutant and its toxic effects in the exposed workers during recycling processing and refining are well documented. In the recent past, a growing concern has evidenced on the potential threat of environmental exposure of lead to ecosystem and human health particularly in young children and women. The presence of lead beyond permissible limits in air, water and soil has been reported worldwide. This has resulted in higher uptake of this metal in the fauna and flora in the exposed areas. In early days, focus of the research in lead toxicity was on acute and chronic effects under occupational exposures. The reports that growing children who are liable to retain excess of this metal through food chain and air exhibit behavioural and other ailments at very low levels has led to research for understanding the subtle, chronic or long term effects where cause and effect relationships are not apparent or may be sub-clinical. This may include changes in the performance of the individuals i.e. lower IQ. Attempts have also been made to develop new sensitive and simple methods for the detection of blood levels. Strategies adopted to minimise exposure to lead in countries like USA, Germany and UK have resulted in the lowering of blood level among children.

In India also steps have long been taken to monitor lead levels in water samples of major national rivers, food items and other possible sources, which may contribute lead to the ecosystem and human body. Earlier studies mostly revealed safe lead levels except in few selected places where levels were beyond the permissible limit. Presence of lead in the food items and domestic sources were also found to be due to age-old social habits and raw materials. Growing concern has aroused at the national level about the increase in lead levels in the environment due to rapid industrialisation and sharp increase in petrol driven vehicular traffic. Monitoring of lead and other heavy metals have been undertaken in India under an Integrated Environmental Programme on Heavy Metals (IEPHM), Ganga Action Plan and Rajiv Gandhi National Drinking Water Mission. In addition, monitoring of lead levels in food materials has also been undertaken in some states from time to time. Monitoring of the human blood lead level in Ahmedabad and children and women in some cities has been undertaken. However, no regular monitoring programme on lead levels in environment, food sources and blood has been undertaken at the national level.

Heavy metal toxicity has been an important area of research at Industrial Toxicology Research Centre, Lucknow for last three decades. Besides the occupational health studies, experimental studies on the mechanism of lead intoxication, factors influencing the lead toxicity and curative aspects have been undertaken. The institute has played a major role in national programmes on monitoring of lead level in water and food material. Limited studies on monitoring of blood lead level of exposed population have also been undertaken.

Kaphalia et al (1981) analysed lead levels in water samples collected from various sources in different sites of India and found lead levels well within the permissible levels in all the samples except 3% of the samples of deep tube wells of Pilani. This excess lead level was attributed to industrial activities in the area (Table No. 1).

A similar trend of lead levels in roadside urban water supply samples in Lucknow (500 samples) and Kanpur (150 sample) cities were also observed (Seth et al 1975). All samples contained lead level within the recommended limits for drinking water (Table No. 2). Israili & Khurshed (1991) also found lead within permissible limits in up and down stream Yamuna river samples of Delhi, Mathura, Agra & Allahabad (Table No. 3). Similarly, the samples from various sites of Ganga river from Rishikesh to Bulandshahar showed lead levels within the permissible limits (Israili, 1991) (Table No. 4).

Lead concentration in submerged plants and fish from various sites of river Ganga were observed only in downstream sites and in fishes collected at Kanpur, which was possibly due to discharge of lead containing effluents from various industries alongside the Ganga river in Kanpur city (Table No. 5) (NEERI, 1987). Recently, Rao et al (1998) showed the presence of lead in the effluents as well as in the sediments and water of Mehadrigedda stream of Vishakhapatnam (Table No. 6). In an IEPHM survey in Tamil Nadu and Kerala more than 60%, and in Andhra Pradesh and Karnataka about 30-50% of the samples analysed showed non-detectable level of lead.

The presence of lead in drinking water assumes great importance due to a WHO report bringing down the permissible lead levels in drinking water from 50 mg/l (WHO 1984) to 10 mg/l (WHO 1993).

Survey studies on lead levels in air in some of the Indian cities have also been carried out. Sadasivan et al (1987), found high lead levels in samples from Bombay, Kanpur and Nagpur which are known industrial cities of India (Table No. 7). In IEPHM survey most of the sample analysed had detectable levels of lead. In Orissa, Kerala, Uttar Pradesh, Karnataka, and Bihar more than 10% of the total number of samples analysed had non-detectable levels of lead. In Tamil Nadu and Andhra Pradesh 6 to 8% of the samples had non-detectable lead levels. The highest level of lead observed was 51.82 mg/m³ in a sample collected from Visakhapatnam urban area. Few samples collected from Uttar Pradesh urban area in the winter season showed a lead concentration of 26.2 mg/m³, while the maximum observed levels of lead in samples collected from the Bihar urban area in summer was 10.1 mg/m³. In all other states, the maximum concentration observed was less than 6 mg/m³, which is the acceptable average for urban area. The increased levels of lead in the above mentioned samples may be due to high traffic density at the time of the collection of the samples or as in Visakhapatnam, due to the lead smelting activities.

Lead levels in food samples collected in Ahmedabad city were found to range from 0.55-1.05, 0.20-1.05, 1.8-2.5 and 0.40-1.25 mg/gm in food grains, vegetables, fruits and cooked food respectively (Pandya et al 1983) (Table No. 8). During IEPHM survey, in West Bengal, Orissa and Karnataka, high levels of lead were observed in all the food constituents. Highest concentration of lead was observed in the food items including fish collected from West Bengal. The levels of lead were high in vegetables and spices in Tamil Nadu and Kerala. In Uttar Pradesh, Bihar, Gujarat and Rajasthan the levels of lead in all the food constituents were very low and in the range reported in literature in other countries. Comparing the intake among different socio-economic groups of population in South India, Srikanth et al (1995) suggested that rice could be considered as a source for higher lead intake in the rural population. However, no clinical data to indicate food intake related effects of lead on health is reported from the area (Table No. 9).

Exposure to lead may also occur through food colours. During a 10 year survey of coloured foodstuff samples from various parts of Uttar Pradesh, 5 non-permitted colours namely auramine, Blue VRS, Brilliant Crocein Scarlet, Malachite Green and Sudan III were found to contain lead levels higher than the permissible levels (Khanna et al, 1976) (Table No. 10). Cattle & buffalo milk samples collected from Ahmedabad, Calcutta and Delhi/Ghaziabad showed 0.27-0.28 ppm lead level, which is higher than the normal bovine milk lead level range i.e.0.08-0.13ppm (Dwivedi & Swarup,1995)(Table No.11 ).

Some studies to assess the body burden of lead have also been undertaken in certain parts of India in urban populations. In a study by Sen and Chowdhury (1996) human hair lead levels among 25-35 yrs old male population of Calcutta in three occupationally unexposed population groups from Jadhavpur, Rajabazar and Batanagar were found to be within the normal range (Table No. 12). In a study of the blood lead levels of Bombay residents the geometric mean was found to be 18.4 (males adults range 12.8-36.7 mg/dl), 16.9 (female adults, range 9.2-24.1 mg/dl), 9.4 (Children 5-12 yrs, range 1.8-17.4 mg/dl) (Khandeker 1984) (Table No. 13). Varying higher blood lead levels depending upon the job engaged and length of service among workers in a mining unit have been reported by Bihari et al (1986) (Table No. 14). A correlation between the blood lead level and the air concentration of lead has been reported (1998) (Table No 15). Awasthi et al (1996) reported mean blood lead of 15.65, 13.64 13.57 and 12.99 mg/dl among women in the different localities of urban slums of Lucknow (Table No. 16). In a study at Lucknow, mean maternal blood lead level was found to be significantly higher (P<0.05) in cases of abnormal delivery (22.52 mg/dl) compared to normal delivery cases (19.4 mg/dl). Whereas no significant difference in placental cord blood and fetal membrane lead levels was observed in normal and abnormal delivery cases (Saxena et al 1994) (Table No. 17).

Detailed experimental animal studies on factors that enhance the lead uptake in the body and vitamins and micronutrient that may protect from effects of lead have been undertaken at ITRC. Iron deficiency, protein deficiency and alcoholism were found to enhance the absorption of lead. Vitamins and micronutrient supplementation significantly protected the animals from the adverse affects of the lead. These studies point out the need for maintenance of proper nutritional status among children and other population (Table 18-20).

In recent years at national level, steps taken to control and prevent the environmental lead exposure include phasing out use of leaded-petrol, developing green belt around industrial areas and areas of high vehicular traffic and monitoring of the environmental lead levels. Keeping in view of the health risks to women and children a comprehensive plan to control, reduce and prevent lead exposure and intervention strategies is needed. This would include monitoring of the lead level in water, food and blood at specified intervals, and health effect assessment of exposed population particularly women and children, keeping in view of the confounding factors and assessment of their nutritional status. This would require interdisciplinary approach, co-ordination at all levels, public awareness and community involvement. Research in this area needs to focus on understanding the factors influencing the low-level toxicity of lead, and development of sensitive portable instruments suitable for measurement of lead in our environment and exposed individuals.

Table no. 1: Lead in drinking water

Range wise % frequency of lead conc.

in different water samples

category	< 0.025 mg/l	0.026-0.050 mg/l	>0.051mg/l
Tap water
Lucknow	50	25	25
Tubewell water
Kanpur	84	16	-
Tube well water
Pilani	-	24	76
Tubewell water
Cambay, Gujrat	55	30	15
Gomti river water	30	65	5
Tank water
Cambay, Gujrat	100	-	-

Source: Kaphalia et al. Ind. J. Environ. Prot.(1981).

Table no. 2: Lead levels in urban water supply

city	range of pb level (mg/l)
	£ 0.001	0.001-0.004	0.004-0.006	0.006-0.05
Lucknow	44.8%	46.4%	7.2%	1.6%
	³ 0.002	0.004-0.008	0.014-0.018
Kanpur	6.7%	80%	13.3%

Source: Seth et. al.,Ind. J.Indus. Med. (1975)

Table no. 3:

Sampling stations
	pb (ug/l)
1. Delhi (upstream)	1.4
2. Delhi (downstream)	2.51
3. Mathura (upstream)	6.50
4. Mathura (downstream)	8.51
5. Agra (upstream)	2.15
6. Agra (downstream)	3.15
7. Allahabad (upstream)	2.12
8. Allahabad (downstream)	4.45

Concentration of lead in Yamuna river water (Israili & Khurshhed, poll. res.,1991). permissible limit (ESEPA) 50 ug/l.

Table no. 4

Sampling sitepb (ug/l)

1. Rishikesh	0.92
2. Haridwar	0.98
3. Sultanpur	1.30
4. Muzaffarnagar	1.20
5. Meerut (Parichchatgarh)	4.50
6. Ghaziabad (Garhmukteshwar)	6.50
7. Bulandshahr	2.70
8. Buladshahr (Ramghat)	2.50

Occurrence of lead (g/l) in Ganga river water in u.p. Israili., Poll. Res., 1991). permissible limit: 50 ug/l

Table no. 5: Concentration of lead in submerged plants and fish from Ganga river

 

plants (g/g)	fish (g/g)
Narora	4.80	3.83
Kannauj	4.00	1.44
Kanpur	upstream	9.80
	downstream	13.70	21.16
Fatehpur	11.96	5.10
Allahabad	3.40	15.33
Varanasi upstream	7.70	14.41
downstream	9.60
Patna	upstream	6.00	10.25
	downstream	9.20

Source: River Ganga: an over view of environmental research. Neeri, Nagpur., 1987

Table no. 6

month & year	sediment	water	effluents
	(ug/g)	(mg/l)	(mg/l)
Sept,93	27.00	1.90	3.7
Oct,93	26.80	0.95	1.3
Nov,93	26.31	0.03	5.6
Dec,93	35.47	0.45	0.8
Jan,94	46.95	0.03	3.4
Feb,94	25.66	2.23	4.2
Mar,94	35.12	2.03	3.0
Apr,94	47.45	1.53	4.0
May,94	48.73	1.64	3.8
June,94	49.21	1.44	8.5
July,94	45.27	1.42	9.5
Aug,94	18.39	2.22	1.6

Lead concentration of effluents, sediments & water in Mehadrigedda stream of Vishakhapatnam (Rao et al., Poll. Res., 1998).

Table no. 7: Concentration of pb in air in few cities

pb in air ug/m³

^{-------------------------------------------------------------------------------------}

city	mean+s.d	min.	max.
Bombay (88)	0.21 + 0.20	0.02	0.83
Bangalore (55)	0.08 + 0.05	0.02	0.15
Nagpur (60)	0.15 + 0.01	0.04	0.68
Jaipur (62)	0.09 + 0.01	0.02	0.26
Chandigarh (33)	0.09 + 0.01	0.02	0.22
Kanpur (15)	0.31 + 0.10	0.10	1.41
Coimbatore (8)	0.06 + 0.02	0.02	0.15

Atmospheric lead levels in some cities in India

(Sadasivan et al.ind. J.Environ.Hlth., 1987)

Table no. 8: Lead levels in food samples / cigarettes collected in Ahmedabad

 

Samples	mean conc.(and range) of lead (ug/gm.)
food grains	0.69 (0.55-1.05)
vegetables	0.74 (0.20-1.05)
fruits	1.8-2.5
cooked food	0.84 ( 0.40-1.25)
cigarettes & beedies	12.43( 7.37-20.4)

(Source: Pandya et al., J. Environ. Biol.,1983)

Table no. 9

pb intake (ug/day)

major food items	Higher gr.income	Middle gr.income	Lower gr.income	Rural gr.population
rice	60	68	81	101
idli ravva	16	16	-	-
sujji	13	13	-	-
wheat flour	29	29	-	-
maida	8	8	-	-
sorgham	-	-	33	-

Role of rice and cereal products in dietary lead intake among different socio-economic group in South India. (Srikanth et al., Food Addit. Contam.,1995)

Table no. 10: Lead in various food colours

pb(ppm)
Permitted colours
Single	within permissible limit
blends	within permissible limit
non-permitted colours
single
1. auramine	15.6
2. blue vrs	18.6
3. brilliant crocein scarlet	13.8
4. malachite green	16.4
5. sudan iii	34.2
blends	within permissible limit

Data of a 10-year survey of 12575 coloured foodstuff samples from various parts of u.p.

(Khanna et al., J Food Sci. Agric, 1976) permissible range - 10 ppm

Table no. 11: Lead in blood and milk from urban Indian cattle and buffalo

urban area	pb conc.in ppm
	blood	milk
	(mean+s.e.)	(mean+s.e.)
Ahmedabad	0.04+0.03	0.28+0.06
(27)	(14)
Calcutta	0.31+0.04	0.28+0.05
(21)	(14)
Delhi/	0.41+0.06	0.27+0.05
Ghaziabad	(18)	(9)

Figures in parentheses show number of samples

Normal bovine milk lead ~ 0.08-0.13 ppm and blood lead~ 0.13 +0.044 ppm (Dwivedi & Swarup,Vet.Human Toxicol.,1995)

Table no. 12: Human hair pb levels in 3 occupationally unexposed population

groups in Calcutta

area	pb (mg/gm)
	Jadavpur	Rajabazar	Batanagar
N	50	50	25
AM	4.52	6.91	3.48
SD	2.92	3.04	0.81
Range0.11-12.10	2.60-19.16	2.10-4.90

Critical hair pb level >20.00 mg/g. study included only 25-35yr. old males

(Sen & Choudhury, Bull. Environ. Contam.Toxicol.,1996)

Table no. 13: Blood lead levels of Bombay residents

Sample	no. of subjects	geometricrange	mean(ug/dl)
total	45	17.7	9.2-36.7
male (adults)	23	18.4	12.8-36.7
female (adults)	22	16.9	9.2-24.1
children (5-12 y)	26	9.4	1.8-17.4
Pune city	21	12.1	4.5-25.0

Source:Khandekar et al., The science of total environment (1984).

Table no. 14: Blood lead levels among workers engaged in a lead mining unit

subject	length of	job requirement	blood lead
(n)	service (yrs)	(ug/dl)
6	8-10	drilling	53.25 (36.3-72.5)
6	2-4	mining workers	53.12 (28.8-87.5)
2	8	Underground Survey	23.00 (20.7-25.4)
2	2-8	Fitters	58.3 (47.1-69.5)
1	8	pump operator	43.7
4	8-12	plant attendant	64.58 (45.8-88.7)
4	8-12	Crushing plant	28.00 (12.0-37.5)
		Worker
4	2-12	Maintenance	16.8 (13.8-20.7)
5	-	Controls	28.0 (15.0-38.0)

Source : Behari et al., Ind. J. Occup. Hlth. (1986)

Table no. 15

areas	shahpur jat (n= 90)	daryaganj (n= 90)
	(%)	(%)
	(low air lead area)	(high air lead area)
category i (<10 ug/dl)	44.4	27.7
category ii (10-19 ug /dl)	14.4	20.0
category iii (20-44 ug /dl)	15.5	31.1
category iv (45-69 ug /dl)	7.7	8.8
category v (> 70 ug /dl)	17.7	12.2
mean	18+12.8	18+8.6

Pilot study on blood lead levels and clinical manifestations in school children of Delhi.

Table no. 16: Distribution of blood pb by type of neighbourhood

nn	slumswomen	mean
(n)	(n)	blood	pb (g/dl)
inner city	36	197	15.65+8.17
industrial	9	9413.57+6.40
(with potentiallead
emission)
industrial	56412.99+7.14
(without potential
lead emission)
near highways	20	14513.64+8.40

Blood lead level in pregnant women in the urban slums of Lucknow (Awasthi et al., Occup. Environ. Med., 1996)

Table no. 17

pb levels	n	normal	n
abnormal	p
	delivery	delivery
maternal184	19.40	47	22.52<0.05
blood
(ug/dl)
placenta	192	17.98	25
20.88n.s.
(ug /100g)
cord blood189	16.96	26	16.38n.s.
(ug /dl)
fetal memb-	187	12.72	25
13.96n.s.
rane (ug /100 g)

Blood and placental lead levels in an Indian city: A preliminary report (Saxena et al., Arch. Environ. Hlth., 1994)

Table no. 18: Protective role of various agents in lead toxicity

(experimental studies)

vitamin supplementation

Flora et al.,Z. Gesamte Hyg,1984

Tandon et al., Ind. J. Med. Res., 1984

Flora et al., Life Sci.,1986,

Flora et al., Biol Trace Elem., 1986,

Tandon et al., Industr. Hlth., 1987

micronutrient supplementation

selenium

Flora et al., Acta Pharmacol.Toxicol., 1983

Tandon et al., Ind. J. Physiol. Pharmacol., 1992

zinc

Hasan & Seth., Toxicol. Lett., 1981

Srivastava & Tandon, Toxicol Lett., 1984

Anwar et al., Drug Chem. Toxic., 1988

Flora & Tandon,Toxicology, 1990

Calcium

Anwar et al., Drug Chem.Toxicol.,1987

Table no. 19: Predisposing factors in lead toxicity

Protein deficiency

• increased embryo and fetotoxicity
• reducedtesticular enzymes activity

Table no. 20: Predisposing factors in lead toxicity

Iron deficiency

.enhanced toxic effects on

neurochemicals/enzymes

.increased accumulation of lead

.increased embryo and fetotoxic effects

Reference

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