Association between blood lead levels and environmental exposure among Saudi schoolchildren in certain districts of Al-Madinah

Figures & data

Table 1 Possible sources of lead^6–10

Occupational

Painters

Home remodelers/renovators

Construction/Demolition workers

Bridge maintenance/repair

Auto body repairers/painters

Battery manufacturers/recyclers

Radiator repairers/manufacturing

Furniture refinishers

Plumbers, pipe fitters

Roofers

Lead miners, smelters, and refiners

Glass, copper and brass manufacturers

Boat builders/painters/repair/ maintenance

Ceramics making/Glaze mixing

Printers (ink)

Plastic and rubber manufacturers

Police officers

Firing range instructors

Steel welders or cutters

Jewelry making

Gas station attendants

Aircraft repair

X-ray shielding/Film radiology

Hobbies and related activities

Home remodeling/renovation

Car or boat repair

Glazing/Making pottery

Reloading/Target shooting at firing ranges

Furniture refinishing

Making/Handling lead shot and fishing weights/sinkers

Using lead soldering/welding

Oil painting (artistic)

Using pastel art pencils

Making stained glass

Jewelry making

Using/Making diving and exercise weights

Repairing old painted wooden or metal toys

Environmental/Other

Lead-based paint (pre-1978)

Soil/Dust near lead industries, roadways,

Plumbing and solder

Cosmetics and hair dye

Imported vinyl mini-blinds

Imported ceramic tiles for the kitchen/bathroom

Building materials

Gutters, flashings, tiles, window glazing

Ceramic ware/glazed pottery

Porcelain bathtubs

Leaded glass/pewter

Leaded gasoline (race, collector cars)

Soldered seams-imported canned food

Soldered copper pipes

Submersible pumps in wells

Brass plumbing fixtures

Bronze, pewter, leaded crystal

Electronics manufacturers Pesticides

Storage batteries

Plastic insulation on electrical wiring and old telephone wiring

Ingested sources

Traditional/Home remedies (eg, azarcon, kohl, ayurvedic)

Imported candy and candy wrappers

Supplements (eg, calcium)

Note: Lead-based paint and lead contaminated dust are the most common sources of lead exposure for children.

Table 2 Demographics of the students in the blood lead level (BLL) survey by school grade, sex, age, and BLL

Parameters	School level						Total
	Elementarya		Intermediateb		Secondaryc
	N = 204	%	N = 188	%	N = 165	%	N = 557	%
Sex
Males	109	53.4	102	54.3	85	51.5	296	53.0
Females	95	46.6	86	45.7	80	48.5	261	47.0
Age in years
6 < 12	204	100.0	–	–	–	–	204	36.6
12 < 15	–	–	188	100.0	–	–	188	33.7
15 < 18	–	–	–	–	165	100.0	165	29.6
BLL (μ/dL)
<1 μ/dL	39	19.1	38	20.2	28	17.0	105	18.9
1 < 2.5 μ/dL	28	13.7	30	16.0	32	19.4	90	16.2
2.5 < 5 μ/dL	25	12.3	26	13.8	30	18.2	81	14.5
5 < 7.5 μ/dL	47	23.0	40	21.3	23	13.9	110	19.7
7.5 < 10 μ/dL	56	27.5	43	22.9	41	24.8	140	25.1
≥10 μ/dL	9	4.4	11	5.8	11	6.7	31	5.6

Notes: Values are expressed as means ± standard deviation or percentage scores. The sample size of each school level was calculated according to the number of students in each school grade level.

a Elementary: school grade levels from grade 1 to grade 6.

b Intermediate: school grade levels from grade 7 to grade 9.

c Secondary: school grade levels from grade 10 to grade 12.

Abbreviation: BLL, blood lead level.

Figure 1 Education and work status of father and mother.

Notes: Values are expressed as means ± standard deviation or percentage scores. Odds ratios with 95% CI are reported for all variables entered into multivariate analysis (P < 0.05).

Table 3 Association between blood lead level and family and personal habits

	<10 μg/dL, n = 533		≥10 μg/dL, n = 24		OR*	CI at 95%
	N	%	N	%
Use of bakhoora
No	100	18.8	1	4.2	5.3	5.0–6.1
Yes	433	81.2	23	95.8
Passive smoking
No	313	58.7	9	37.5	2.4	1.2–5.5
Yes	220	41.3	15	62.5
Putting colored toys in the mouth
No	313	58.7	2	8.3	15.7	3.6–16.2
Yes	220	41.3	22	91.7
Using colored pencils
No	117	22.0	1	4.2	6.5	4.8–8.7
Yes	416	78.0	23	95.8
Some food habits
Eating canned food
No	159	29.8	1	4.2	9.8	7.0–10.1
Yes	374	70.2	23	95.8
Drinking canned juice
No	88	16.5	2	8.4	2.2	1.4–3.8
Yes	445	83.5	22	91.6
For females only (n = 262)
Cosmetic use
No	127	52.0	1	5.6	18.5	14.4–19.8
Yes	117	48.0	17	94.4
Use of kohlb
No	64	26.2	1	5.6	6.0	5.7–8.3
Yes	180	73.8	17	94.4
Use of lip gloss
No	68	27.9	1	5.6
Yes	176	72.1	17	94.4	6.6	6.1–7.4
Use of toothpaste
No	121	22.7	1	4.2	6.8	5.8–7.8
Yes	412	77.3	23	95.8
Use of newspapers in:
Playing
No	473	88.7	21	87.5	1.1	1.1–3.9
Yes	60	11.3	3	12.5
During food preparation
No	356	66.8	5	20.8	7.6	6.3–8.2
Yes	177	33.2	19	79.2
Wrapping and preserving food
No	416	78.0	10	41.7	5.0	2.2–3.5
Yes	117	22.0	14	58.3
As table mats
No	333	62.5	5	20.8	6.3	5.2–7.6
Yes	200	37.5	19	79.2

Notes: Values are expressed as means ± standard deviation or percentage scores.

a “Bakhoor,” from the Arabic language, is today used to describe most incense resins or fragranced wood chips.

b Kohl is an ancient eye cosmetic.

* Odds ratios (OR] with 95% confidence interval (CI) are reported for all variables entered into multivariate analysis (P < 0.05).

Table 4 Correlation between blood lead level and some studied characters (cluster analysis)

Parameters	< 10μg/dL		≥ 10μg/dL		All studied groups
	Ra	Significance	Ra	Significance	Ra	Significance
Housing construction characteristics	0.023	0.603	0.024	0.580	0.046	0.282
Family habits	0.278**	0.000	0.051	0.811	0.255**	0.000
Personal habits	0.208**	0.000	0.060	0.781	0.321**	0.000
Eating habits	0.078	0.073	0.248	0.243	0.128**	0.002
School building characteristics	0.016	0.704	0.093	0.664	0.469**	0.000

Notes:

a Spearman’s correlation was used;

** correlation is significant at 0.01 (two tailed).

Figure 2 Association between BLL and scores of possible lead exposure (odds ratios [OR]).

Notes: Values are expressed as means ± standard deviation or percentage scores. Odds ratios with 95% confidence intervals (CI) are reported for all variables entered into multivariate analysis (P < 0.05).

Table 5 Mean percent score of possible sources of lead exposure

	<10 μg/dL	≥10 μg/dL	P valuea
Household exposure	51.36 ± 12.67	54.69 ± 12.67	0.205
School exposure	66.94 ± 6.60	65.83 ± 6.53	0.420
Family habits	43.04 ± 19.09	75.83 ± 22.06	0.000*
Personal habits	55.56 ± 17.74	78.70 ± 10.32	0.000*
Eating habits	30.89 ± 21.35	72.22 ± 30.56	0.000*
Total exposure score	49.56 ± 8.78	69.46 ± 8.69	0.000*

Notes:

a P for t-test;

* P value significant below 0.05.

Table 6 Relationship between blood lead level and hemoglobin level by age group

	<10 μg/dL, mean ± SD	≥10 μg/dL, mean ± SD	P value
6 ≤ 12 years (both sexes)
All group (N = 235)	12.40 ± 1.17	9.33 ± 0.94	0.000*
Non-anemic group (N = 204)	12.77 ± 0.58	10.66 ± 0.68	0.000*
a Anemic group (N = 31)	10.09 ± 1.28	8.87 ± 0.75	0.000*
12 ≤ 18 years
Males
All group (N = 172)	13.45 ± 0.90	10.55 ± 1.27	0.000*
Non-anemic group (N = 129)	13.85 ± 0.49	–**	–
b Anemic group (N = 43)	12.13 ± 0.67	9.00 ± 0.00***	0.000*
Females
All group (N = 150)	12.31 ± 1.11	10.42 ± 1.26	0.000*
Non-anemic group (N = 103)	12.86 ± 0.61	12.0 ± 0.00***	0.165
c Anemic group (N = 47)	10.26 ± 1.21	10.89 ± 0.74	0.041*

Notes:

* P value for t-test significant below 0.05;

** number = 0;

*** number = 1;

a normal range for this age: 11.5–13.5 mg/dL;

b normal range for age and sex (male): 13–14.5 mg/dL;

c normal range for age and sex (females): 12–14 mg/dL.

Table 7 Predictors of high blood lead level among schoolchildren

	B	β	t	Significance	95% of CI for B**
Use of bakhoora	0.006	0.012	0.309	0.757	−0.034 to 0.046
Use of toothpaste	0.074	0.151	3.710	0.000*	0.035–0.113
Use of kohlb	0.080	0.194	4.671	0.000*	0.046–0.114
Passive smoking	0.027	0.065	1.693	0.091	−0.004 to 0.57
Putting colored toys in mouth	0.057	0.140	3.613	0.000*	0.026–0.088
Use of canned food	0.051	0.113	2.674	0.008*	0.014–0.088
Use of canned juice	0.056	0.101	2.366	0.018*	0.010–0.102
Use of cosmetics	0.019	0.039	0.720	0.472	0.071–0.033
Use of lip gloss	0.118	0.270	4.587	0.000*	0.067–0.168
Use of newspapers
Food preparation	0.062	0.146	3.509	0.000*	0.027–0.097
Table mats	0.130	0.312	6.999	0.000*	0.093–0.166
Wrapping	0.960	0.200	4.940	0.000*	0.058–0.134
Use of colored pencils	0.027	0.054	1.400	0.162	−0.011–0.065

Notes:

* Significance below level of 0.05;

** Confidence interval (CI).

a “Bakhoor,” from the Arabic language, is today used to describe most incense resins or fragranced wood chips.

b Kohl is an ancient eye cosmetic.

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