Lead is a toxin that can cause high blood pressure in pregnancy, which in turn can predispose women to pre-eclampsia during pregnancy and heart disease later in life. Lead accumulates in the bones and can remain there for up to 30 years.
Exposure to high levels of lead while in the womb, when it is transferred from the mother, can affect the unborn baby’s developing nervous system. It can also have a longer-term detrimental effect on the child’s health, academic performance and behaviour.
Lead is widespread in the environment, particularly in areas with smelters, lead works, and battery manufacturing and recycling. Food, water, dust and soil are other important sources of exposure.
There are no recommendations for blood lead levels in pregnancy and childhood in the UK but the Centers for Disease Control and Prevention (CDC) in the US recommend levels are kept below 5 micrograms per decilitre (µg/dl).
The research published today in PLOS ONE looked at 4,285 mother–child pairs in the Children of the 90s study and found that women with blood lead levels above five µg/dl were more likely to have attended university, and to smoke and consume alcohol and coffee.
The researchers say that the unexpected finding that higher educational levels were associated with higher lead levels supports recent evidence that we shouldn’t assume that more disadvantaged populations have higher exposure to environmental pollutants.
The study produced some other unexpected findings:
- The average blood lead level in this group of pregnant women is higher than has been found in similar groups in other developed countries;
- Women who had lived in the area of Avon all their lives had lower blood lead levels than those who had not;
- Women of Indian, Pakistani and Bangladeshi ethnicity had higher blood lead levels than white women.
Although the analysis was conducted on data that were gathered in 1991, it is the largest study of blood lead levels ever undertaken in the UK. Levels in pregnancy in the UK have only been reported four times in the past: the last time was in 1996 on a small sample of 138 women also studied in 1991.
Dr Caroline Taylor, the lead author from Bristol’s School of Social and Community Medicine, said: “Pregnant women should not be concerned by this new report. Our research reinforces the current advice to women who are pregnant or planning a pregnancy that they should stop or reduce their alcohol and caffeine intake and give up smoking if they can. They should follow a healthy diet with good sources of calcium and iron.
“Even though lead levels may have dropped since our data were gathered in 1991, due to the removal of lead from paint and petrol, there is no existing evidence to back this up in the UK. Our research highlights the need for an up-to-date study of lead levels in pregnant women in the UK.”
The paper, ‘Environmental Factors Predicting Blood Lead Levels in Pregnant Women in the UK: The ALSPAC Study’ by Taylor, C et al is published today in PLOS One, doi 10.1371/journal.pone.0072371