Exposure to lead especially in childhood can have a lifetime of negative consequences:
According to the WHO, there is no known safe level of lead exposure. Relatively low levels of lead exposure that were previously considered ‘safe’ have been shown to damage children’s health and impair their cognitive development. Lead is a potent neurotoxin that, with even low-level exposure, is associated with a reduction in IQ scores, shortened attention spans and potentially violent and even criminal behaviour later in life. Children under the age of 5 years are at the greatest risk of suffering lifelong neurological, cognitive and physical damage and even death from lead poisoning.
In recent decades, some countries have begun to address the problem by removing lead from gasoline, paint, and pipes. Lead poisoning, however, remains a serious problem in South Asian countries such as Bangladesh. But where is the lead coming from?
Incredibly, one small study that examined the blood of pregnant women in Bangladesh for lead isotopes concluded that a major source of lead exposure is from turmeric consumption. Turmeric is a spice used in India and Bangladesh and other South East Asian both in cooking and for health. Lead from the soil could enter turmeric but the major cause seems to be lead pigments that are illegally added to turmeric to give it a pleasing looking yellow color. Lead in spices can exceed national limits by hundreds of times.
Our results indicate that turmeric Pb concentrations were as high as 1151 μg/g (Table 2). Eight of 28 market turmeric samples contained Pb above the 2.5 μg/g Government of Bangladesh limit for Pb in turmeric (Table S6). Using the simplified bioaccessibility extraction test, prior studies reported that the bioaccessible fraction of Pb in turmeric varied from 42.9 to 70% of total Pb. (12,39) Given that turmeric is used in dishes containing tamarind and other acidic ingredients, cooking could further increase the bioaccessibility of the Pb. (40) Other researchers hypothesized that PbCrO4 is added to turmeric to enhance its color or weight, but they did not test any turmeric processing powders to assess molar Pb/Cr ratios or Pb speciation. (12) We found that the yellow pigment powders used in turmeric processing contained 6–10% Pb by weight (61 870–101 300 μg/g Pb). Both pigment and turmeric samples also contained elevated chromium (Cr) concentrations, with average Pb/Cr molar ratios of 1.3 ± 0.06 (2 SD) and 1.1 ± 0.8 (2 SD), respectively. X-ray diffraction analyses indicated that all three pigment samples contained lead chromate (PbCrO4, 10–15%), that two of the pigments also contained lead carbonate (PbCO3, 2–3%), and that one also contained lead sulfate (PbSO4, 3%). Because PbCO3 and PbSO4 have a greater bioaccessibility than PbCrO4, our results support the parallel findings of high turmeric bioaccessibility reported in other studies. (12,39,41)
Respondents described turmeric, primarily purchased as a loose powder, as one of three essential spices consumed daily, alongside chili powder and cumin. Women reported adding turmeric in heaping spoonfuls to curries and other dishes for at least one meal per day.
I’d also worry about lead adulteration of safron, another yellow spice. The problem is not limited to Bangladesh, significant amounts of lead have been found in spices sold in in New York.
Addendum: Givewell has a good rundown on Pure Earth a charity working to address this problem.
Hat tip: Alexander Berger.
Photo Credit: MaxPixel.
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