Background:

No level of lead exposure is considered safe, and humans have experienced its toxicity to nearly every organ system, especially the central nervous system (1,2).  Exposures to lead, especially for the developing neurological system of children, are known to be hazardous and greatly impact children (2).

Environmental contamination is a widespread public health issue throughout the country of Bangladesh. Within the 1990s, widespread arsenic poisoning was described in populations which used groundwater wells for drinking water and were contaminated with naturally-occurring arsenic (3). In addition, Bangladesh is a developing country with increasing industry and continued burning of gasoline pointing to high exposures of lead through air pollution (4). Children also make up about 13% of the labor force in Bangladesh which include pottery glazing, lead melting, welding, car repair, and ship breaking which are all known exposures of lead (5). Based on historical air pollution and industries within urban areas of Bangladesh, the exposures to lead and known elevated childhood blood levels alarm health authorities and more information is needed as to determine exact exposures within communities.

I will utilize a 16-year developed maternal cohort study (R01ES015533 PI:Christiani/CoI Kile; P42ES16454: Bellinger/CoI: Kile; R01ES023441,PI: Kile) in Pabna and Sirajdikhan Upazilas in Bangladesh to examine the possible spatial relationships of lead exposures. Children born from the participating mothers in the maternal study were followed from early childhood and were tested for blood lead levels at 4 to 5 years old. Many children within this cohort showed elevated blood lead levels above the U.S. recommendation level of 5 ug/dL (Table 1).

Table 1: Summary results of blood lead levels (ug/dL) of children aged 4-5 years in Pabna and Sirajdikhan (n=348)

Location	Minimum	Mean	Maximum	Above 5 ug/dL and percentage
Combined	0.00	3.86	19.6	165, 47%
Pabna (n=183)	0.00	1.32	10.8	51, 28%
Sirajdikahn (n=165)	0.00	6.67	19.6	114, 69%

Research question:

What are the potential spatial relationships of blood lead levels in children aged 4-5 years old within two areas in Bangladesh and association with possible sources of exposure from high traffic or urban areas?

Dataset analyzing:

Blood lead concentrations (ug/dL) of children at ages 4-5 years old only taken at one timepoint with coordinates of their homes (n=348). There is one other categorical variable of if the children are above or below the 5 ug/dL US recommendation for lead exposure. The resolution is fine scale within meters of one another over the span of square kilometers. I will also be employing base maps of the two districts where the children live. This will allow network review for the major traffic and highway areas and distance to urban centers. I have a slight hesitation for the level of information I will have within the country of Bangladesh for understanding the street network. My pilot data from analysis in R made it difficult to gather these data. I am looking to import the data into Arc for more extensive data analysis.

Hypotheses:

I hypothesize that the blood lead levels of the children are spatially correlated and increased blood lead levels in either specific hot spots and/or locations closer to roads and/or urban centers will be due to inhalation and dermal exposure from air pollution.

Approaches:

I would first like to perform spatial autocorrelation to determine if the blood lead levels of children are spatially correlated.  Secondly, I would like to employ the hot-spot analysis tool from Arc to determine if within the sample of children there are specific hotspots of higher blood lead levels. We do know that between the two districts of samples taken, the district closer to urban landscape has higher, more prevalent levels of lead in children (Table 1). To try and pinpoint more specific exposures, I would like to intersect the locations of the children’s homes with a buffer (100 m) from major highway and traffic areas. I would then aggregate the intersected homes and determine if those blood lead levels are higher comparatively to the children that live greater than 100 m. The first attempt would be crude analysis of within or outside the buffer, but if we do find that individuals within the buffer have significantly higher blood lead levels, I would like to see if there is a drop off of between 100-250 m, 250 – 500 m, and 500 m + in distance from high traffic roadways. Lastly, if we do not find trends with distance to roadways and blood lead levels, I will overlay base maps of industry related areas and identify if they overlap with hot spots within our spatial spread of the blood lead levels.

Expected outcomes:

1. Spatial autocorrelation: I hope to describe the blood lead level data as spatially autocorrelated by producing linear plots as a visual representation of their autocorrelated relationships
2. Hot spot analysis: From Arc, I will produce maps through the hot-spot analysis tool to hone into different areas of interest that might have the highest levels comparatively. This map would be useful to understand blood lead level relationships within the two different districts, and if there are areas of interest for further analysis.
3. Distance to roadways: From Arc, I want to produce maps that show a 100 m buffer around major roadway systems and intersection of locations of children’s homes from the cohort. I would then like to graphically produce a simple boxplot of blood lead levels within the buffer and outside of the buffer zone to compare the mean blood lead levels. If I do find differences, I would like to produce another map of the gradient change of going farther away from high traffic roadways and blood lead levels (further buffer/intersection analysis).
4. Intersection of Hot Spots and Industry: I would like to produce a map similar to the hot-spot analysis which overlays the areas of known industry from a base map with the potential hot-spots of children’s homes.

Significance:

In a 16+ year cohort understanding the consequences of chronic arsenic exposures, my work is significant to help communities better protect children from undue burden of environmental pollution. I hope to bring a better understanding to the communities as to why their children have high blood lead levels compared to US averages. My research will help explain if the areas the children live in are correlated with increased exposures and lead to more help public health actions on how to limit lead exposures.

Level of preparation:

a) Intermediate knowledge of ArcGIS Pro

b) I will concurrently be taking a GIS programming course in Python, and I have taken intro Python coding coursework.

c)I have completed coursework (GEOG 561) programming in R with these data to understand spatial relationships. I also have extensive statistical modeling experience in R.

Works Cited:

1. Tong S, Schirnding YE von, Prapamontol T. Environmental lead exposure: a public health problem of global dimensions. Bull World Health Organ. 2000;78:1068–77.
2. WHO | Lead [Internet]. WHO. [cited 2019 Mar 17]. Available from: http://www.who.int/ipcs/assessment/public_health/lead/en/
3. Smith AH, Lingas EO, Rahman M. Contamination of drinking-water by arsenic in Bangladesh: a public health emergency. Bull World Health Organ. 2000;78(9):1093–103.
4. Kaiser R, Henderson A K, Daley W R, Naughton M, Khan M H, Rahman M, et al. Blood lead levels of primary school children in Dhaka, Bangladesh. Environ Health Perspect. 2001 Jun 1;109(6):563–6.
5. Mitra AK, Haque A, Islam M, Bashar SAMK. Lead Poisoning: An Alarming Public Health Problem in Bangladesh. Int J Environ Res Public Health. 2009 Jan;6(1):84–95.

Faye Andrews, MPH

andrewsf@oregonstate.edu