Aligarh, a densely populated town of Uttar Pradesh, is the hub of a variety of industries and is feared to be home to children at risk of lead exposure. Hence, this study was planned to determine the socio-demographic and clinical correlates of elevated blood lead levels in children of Aligarh.

This was a hospital-based cross-sectional study carried out in children (6-144 months) attending pediatrics Out Patient Department (OPD) for either routine check-up or any physical symptom suggestive of lead poisoning like pallor, unexplained fatigue, abdominal pain, constipation or anorexia, deteriorating school performance, and recently acquired irritability or hyperactive behaviour. The children were excluded if they required admission or were taking/had taken calcium, zinc or iron supplementation in past two months. The period of the study was from February 2014 to September 2015.

The study was approved by the Institute Ethics Committee, and informed written consent was obtained from the parents/legal guardians. Details about the child’s habits, rearing environment like distance from traffic (less than 100 m, 100-500 m, more than 500 m), source of drinking water, as well as maternal and paternal attributes likely to cause exposure to lead were enquired. Child’s symptoms, especially of gastro-intestinal and neuro-behavioral origin were enquired and a general physical examination carried out. All the data were entered in a pre-designed proforma.

Considering the prevalence of elevated blood lead level as 12% and level of confidence of 2%, and the degree of precision as 4%, the sample size was calculated to be 260 [6].

For estimation of blood lead level, after aseptic site preparation, venous blood was drawn in Ethylene diamine tetra-acetic acid vacutainers. The labelled sample was stored in the freezer compartment (-18ºC) of the refrigerator in a sealed and airtight container to avoid contamination during storage, till it was transported to Department of Biochemistry, King George Medical University, Lucknow for analysis. Lead level was estimated by Inductively Coupled Plasma-Optical Emission Spectrometer with the help of Microwave Digestion System. A value of 10 µg/dL was considered as the cut-off for elevated blood lead levels (BLLs).

Hemoglobin estimation was done by Sahli’s hemoglobinometer. The presence of anemia was defined as per WHO cut-offs [7]. Statistical analysis was done using the Statistical Package for Social Sciences (SPSS 17) for Windows. Pearson’s chi-square test was applied to sets of categorical data. P value <0.05 was taken as statistically significant.

A total of 335 children were approached, 55 refused consent while 20 had one of the exclusion criteria; 260 children (59.6% males) were eventually enrolled in the study. The mean (SD) age of the study group was 54.4 (9.6) months.

The prevalence of elevated BLL was found to be 44.2%; the mean (SD) value was 55.7(227.38) µg/dL [Median (IQR) 8.4 (0-33)µg/dL] . Among the children with elevated blood lead levels, majority of children (67.8%) did not show any clinical symptoms suggestive of lead poisoning. The mean (SD) BLL was highest in age group 6 to 12 months [33.8 (5.1) µg/dL] and lowest in age group 120 months [10.9 (4.4)µg/dL]. There was no difference in lead levels across sexes.

Table I	Relationship of Child Attributes with Blood Lead Levels (N=260)

Although factors like presence of pets in house, use of colored toys (soft vividly colored plastic toys), regular eating food-items from street vendors (yellow/ bright colored food items, candies etc.) and use of kohl were found more in children with elevated BLL than those having normal blood lead level, the differences were not found to be statistically significant (Table I). Neither the source of water supply nor the use of purification method was found to affect the BLL. Maternal use of cosmetics like sindoor, lipstick and dye was found more in children with elevated BLL; however, the difference did not reach the level of significance (Web Table I).

Among the demographic factors, wall paints done more than 5 years back were significantly associated with elevated BLL in children (Table II).

Table II	Relationship of Blood Lead Levels with Time Since Last House-Paint

The prevalence of elevated BLL in children of Aligarh attending Pediatric OPD was found to be 44%. None of the child’s habits or parental attributes were found to be related to the BLL in children, only old and deteriorating paint on the house walls was significantly associated with elevated BLL. The flakes of old paints are likely to be chipped off from the wall and contaminate the house dust, which may be later ingested by the child through unhygienic eating habits. This could also explain increased risk of elevated blood lead levels in younger children who exhibit more hand to mouth activities and less of hand hygiene. The children with raised BLL remained essentially asymptomatic.

Limitations of the present study were that the drinking water or soil was not analyzed for lead level as these were not included for lead analysis in the protocol. These may be important sources of lead entry into the body, especially for young children who may fail in hand hygiene and ingest soil/mud more than the older children/adults. In addition, the lead content of various colored food items as well as cosmetics may vary, which was not considered while evaluating the risk factors.

Before being phased out, leaded gasoline used to be an important source of lead exposure and elevated BLL in children [6,8]. Another important potential exposure of lead is likely to be lead dust from parents’ work clothing which can be later ingested or inhaled by children at home [9]. However, in the present study we did not find occupation or other parental attributes determining the BLL in children, as also reported by other investigators [10-12]. The strikingly high prevalence of elevated blood lead levels found in Aligarh may be attributable to some other factor not addressed in the present study. In addition, elevated BLL in children was not associated with symptoms, as observed by other investigators [13].

Rising trend of lead poisoning is a cause of serious concern. Lead-based paints and coloring agents continue to be used in India and many other countries of the world. There is dearth of available and affordable laboratory facilities for BLL estimation. We strongly need rigorous control on lead based paints and colouring agents, laboratories for BLL estimation, estimation of lead content in soil and water in high risk areas, as well as community awareness on lead poisoning. Future research should focus on identification of risk factors and burden of this preventable problem through large multicentric epidemiological studies.

Contributors: SC: collection of data and electronic preparation, UF: Study concept, study design,electronic preparation, final revision, SMA: study design, revision of manuscript and AAM: analysis of data, revision of the manuscript.

Funding:None; Competing interest: None stated.