Environmental Factors Predicting Blood Lead Levels in Pregnant Women in the UK: The ALSPAC Study

Abstract

BackgroundLead is a widespread environmental toxin. The behaviour and academic performance of children can be adversely affected even at low blood lead levels (BLL) of 5–10 µg/dl. An important contribution to the infant's lead load is provided by maternal transfer during pregnancy.ObjectivesOur aim was to determine BLL in a large cohort of pregnant women in the UK and to identify the factors that contribute to BLL in pregnant women.MethodsPregnant women resident in the Avon area of the UK were enrolled in the Avon Longitudinal Study of Parents and Children (ALSPAC) in 1991–1992. Whole blood samples were collected at median gestational age of 11 weeks and analysed by inductively coupled plasma dynamic reaction cell mass spectrometry (n = 4285). Self-completion postal questionnaires were used to collect data during pregnancy on lifestyle, diet and other environmental exposures. Statistical analysis was carried out with SPSS v19.ResultsThe mean±SD BLL was 3.67±1.47 (median 3.41, range 0.41–19.14) µg/dl. Higher educational qualification was found to be one of the strongest independent predictor of BLL in an adjusted backwards stepwise logistic regression to predict maternal BLL <5 or ≥5 µg/dl (odds ratio 1.26, 95% confidence interval 1.12–1.42; p<0.001). Other predictive factors included cigarette smoking, alcohol and coffee drinking, and heating the home with a coal fire, with some evidence for iron and calcium intake having protective effects.ConclusionThe mean BLL in this group of pregnant women is higher than has been found in similar populations in developed countries. The finding that high education attainment was independently associated with higher BLL was unexpected and currently unexplained. Reduction in maternal lead levels can best be undertaken by reducing intake of the social drugs cigarettes, alcohol and caffeine, although further investigation of the effect of calcium on lead levels is needed.

Adverse effects of maternal lead levels on birth outcomes in the ALSPAC study: a prospective birth cohort study

“…One sample had a lead level below the limit of detection (0.29  μ g/dl): this sample was assigned a value of 0.7 times the lower limit of detection. The mean maternal B-Pb was 3.67 ± 1.47  μ g/dl ( n  = 4285; geometric mean 3.43, median 3.42, range 0.41–19.14  μ g/dl) 2. The birth outcomes are summarised in Table 1.…”

“…The removal of lead from water pipes, paint and food cans, and a ban on lead additives to petrol in most countries has reduced exposure to lead in recent years, although industrial activities such as mining, smelting, lead shot manufacture and battery manufacture and recycling are still of concern. Food and drink, water, dust and soil remain as important sources of exposure,1 as does cigarette smoking 2,3…”

The Northern Norway Mother-and-Child Contaminant Cohort (MISA) Study: PCA analyses of environmental contaminants in maternal sera and dietary intake in early pregnancy

“…Bjermo et al (2013) have demonstrated meat intake to be inversely related to blood Cd concentrations. Smoking also contributes to increased blood Pb concentrations (Chelchowska et al, 2013;Taylor et al, 2013), and its uptake is found to be inversely related to Fe-stores (Mahaffey, 1990). Exposure of the general population to Pb has been linked to multiple sources including: dietary (e.g., consumption of foods grown on contaminated soils, some wines, hunted game and waterfowl and the associated use of leaded ammunition); leaded paints; contaminated soils and air; and certain hobbies such as making Pb sinkers Meltzer et al, 2013;Hanning et al, 2003).…”

Pilot study testing a European human biomonitoring framework for biomarkers of chemical exposure in children and their mothers: experiences in the UK

“…Human biomonitoring (HBM) provides a more direct measure of actual personal exposure to environmental chemicals, but interpretation can be limited due to a lack of UK population based reference levels to compare with. There are some health-based projects that have contributed to the understanding of environmental chemical exposures in the UK population, such as the Avon Longitudinal Study of Parents and Children (ALSPAC), which has published, for example, on lead and mercury exposures in pregnancy Taylor et al 2013). A study for the UK population by Bevan and colleagues collected data to develop reference ranges for a number of environmental chemicals in widespread use including benzene, cadmium, mercury and naphthalene (Bevan et al 2013).…”