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Dhaka Tribune

What could be the source of higher blood lead level in pregnant women?

A study was conducted on 430 pregnant women of Bangladesh to analyse BLL in their bodies

Update : 18 Jul 2018, 11:00 AM

A recent study has found higher blood lead levels (BLL) among pregnant women in rural Bangladesh. 

The information was published by a collaborative study by International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b) and Stanford University titled “Prevalence of elevated blood lead levels among pregnant women and sources of lead exposure in rural Bangladesh: A case control study” in Environmental Research.

The study analysed BLL among 430 pregnant women and found multiple possible sources, including food and non-food sources.

 “Surprisingly, rather than evidence of a single source causing the elevated lead levels in pregnant women, the study identified multiple possible sources of lead exposure from the environment and food sources,” Stephen P Luby, senior author of the study and professor of medicine at Stanford University, said.

The study found one third of the pregnant women had elevated BLL greater than 5 micrograms per deciliter (DL) while 6% of them had more than 10 micrograms per DL. One sample was found at 29.1 micrograms per DL, which is 6 times greater than the threshold noted by the Centers for Disease Control and Prevention (CDC).

Why and where is the lead coming from?

Of the food and agrochemical samples analysed, seven out of 17 turmeric powder samples had excess lead than the tolerable limit at 2.5 micrograms per gram, designated by Bangladesh Standards and Testing Institution (BSTI), while one unpackaged and unbranded sample contained over 265 microgram/gram lead.

“Compared to women with low blood lead levels, women with the highest blood lead levels were more likely to be exposed to consuming food from lead-soldered metal food containers (cans), consuming food from agricultural fields where herbicide and pesticides have been used and consuming ground rice,” Sarker Masud Parvez, co-author of the study and research investigator at icddr,b, said.

Since women with higher BLL were more likely to have been exposed to possible lead sources in the environment, the researchers examined soil, 382 agrochemical (herbicide and pesticide) samples, and 127 ground and unground rice samples.  

As these cans are old and rusty, it is possible that old and rusted oxidised particles flake off into puffed rice and then inadvertently consumed, according to the study.

 “It is possible that food stored in these cans absorbs lead from the soldered seams, depending on the chemical composition of the food, especially liquid,” said author of the study Jenna E Forsyth, a doctoral researcher at Stanford University.

Since there was insignificant lead level in the soil, rice, and agrochemical samples analysed, the study notes that currently banned agrochemicals may have contributed to lead exposure in the past.

“Lead exposure over time results in lead deposit in the bones and it may be released in the blood during pregnancy,” Dr Rubhana Raqib, co-author of the study and senior scientist and head of immunobiology, nutrition and toxicology laboratory at icddr,b, said.

Therefore, it cannot be ruled out that exposure to lead for these women could have taken place over a decade prior to sample collection, notes the study. 

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