Pregnant women in the country’s rural areas are exposed to toxic lead due to the use of lead-soldered food cans and intake of foods produced in agricultural fields where herbicide and pesticides have been used, according to a study.
The study titled ‘Prevalence of elevated blood lead levels among pregnant women and sources of lead exposure in rural Bangladesh: A case-control study’ was conducted by International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b) in collaboration with Stanford University, USA.
Lead poisoning is a threat for mothers and their developing fetus as well as for the newborn as lead deposits in the mother’s body are released in blood and subsequently into breast milk. Lead exposure in pregnancy interferes with children’s brain development. In adults, lead exposure increases the risk of heart and brain disease.
“The study found lead in the blood cells of the human body, particularly the pregnant women. The study identified various sources of the lead including oil cans and powdered spices such as turmeric powder and agrochemicals,” Sarker Masud Parvez, co-author of the study and a research investigator at icddr,b told the daily sun.
He said they examined the blood lead levels (BLL) among 430 pregnant women and found one-third of them had elevated BLL greater than 5 micrograms per deciliter (DL) while 6 percent 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 Center for Disease Control and Prevention (CDC).
“Compared to women with low blood lead levels, women with the highest blood lead levels were more likely to be exposed to foods from lead-soldered metal food containers (cans), foods from agricultural fields where herbicide and pesticides have been used and ground rice containing a higher level of lead,” Masud Parvez said.
He said since women with higher blood lead levels were more likely to have been exposed to possible lead sources in the environment, the researchers examined soil, 382 agrochemical samples including herbicides and pesticides and 127 ground and unground rice samples.
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). One unpackaged and unbranded sample contained over 265 microgram/gram lead, according to the study.
Experts involved in the study said elevated blood lead levels in pregnant women is a cause for public health concern.
The study report said as a potent neurotoxin, lead poses a serious threat to public health and human intellectual capital worldwide. After exposure via inhalation or ingestion, lead circulates in the blood and is either excreted via urine or deposited in soft tissue or bone. The mean half-life of lead in blood is approximately 21–28 days, whereas lead accumulates in bones with a mean half-life of 5–19 years.
During pregnancy, lead is mobilized from bones back into the maternal blood and readily crosses the placenta into the blood of the developing fetus. Prenatal and early childhood lead exposures affect the developing central nervous system and produce irreversible cognitive damage that leads to adverse outcomes in adulthood. However, there is no known safe level of lead in the body, the study said.
Bangladesh phased out lead in gasoline in 1999, yet BLLs above 5 μg/dL persist across the country. Blood Lead Levels are comparatively higher in urban versus rural areas, though Blood Lead Levels are higher than expected in non-industrial rural agrarian regions. In Dhaka, the capital city of Bangladesh, studies since 2000 have shown mean BLLs between 11.5 and 15 μg/dL among children under 16 years of age.
The experts said for the small percentage of the population that stores food in cans, solder from cans may be a source of persistent low doses of lead that accumulate over many years. Taking action to reduce exposure via this pathway will involve exploring the mechanism by which lead gets from the can to the food, why households store food in lead-soldered cans, where the lead solder comes from, what alternative lead-free solders exist, and what actions by government or other actors could limit the use of lead in repair and recycling activities.
They suggested that that the issue of lead-adulterated turmeric be explored further since we were underpowered to assess this exposure and yet contaminated turmeric consumption could deliver high doses of lead, impacting not only South Asians but the rest of the world through the global supply chain.
“Further investigation on turmeric is underway,” Masud Parvez said.
“The issue of lead exposure was found higher in our study. The lead in the blood can be contaminated. If the lead sources are not stopped it will continuously affect the human body,” a member of the research team and head of ICDDR, B’s Immunobiology, Nutrition and Toxicology Laboratory, Rubhana Raqib, told daily sun.
The experts suggested for ensuring reduction of lead in food and consumer products and lead-free pesticides and fertilizers and sought for legislation and ensuring punishment for the crimes of food adulteration and other sorts of contamination (land, air, water) by industries etc.