How and why does lead chromate (a poison) find its way int0 turmeric powder (an edible spice)?
| Lead chromate | Turmeric |
Lead Chromate. C.I.77600-77603, historical dye collection of the Technical University of Dresden, Germany, Shisha-Tom via commons.wikimedia.org
Turmeric Powder. Sanjay Acharya, en.wikipedia via https://commons.wikimedia.org/
Central Food Technology Research Institute (CFTRI), India, on turmeric processing (Business Standard, 2014)
“In the conventional method of processing raw turmeric tubers for improving their appearance and colour, they are first boiled in cow dung extract and subsequently treated with an emulsion made of castor seed paste, alum and Chemichrome (a brand of lead chromate). The first treatment is neither hygienic nor aesthetic, and the latter contaminates the tubers with lead which is a cumulative poison.”
CFTRI introduced a new method* in 2014 that uses neither cow dung nor lead chromate to prepare turmeric. There certainly was earlier awareness of the problem, as an early paper from CFTRI by Desikachar et al. (1959) shows. [Periodic “discoveries” of the problem reflect periodic awareness in the global context, often related to policy decisions on imports (2013-
Yet, a recent (2019) publication from CFTRI describes the processing of turmeric tubers as using “middle chrome” (aka lead chromate). Is the new method not used generally? Apparently not, as Agmarknet (“connecting farmer to market”) link showed in 2016.
| **Lead chromate | Turmeric whole and powdered, mixed spices | Anemia, abortion, paralysis, brain damage |
[**Update 11 Nov 2023 — this site no longer seems to have information about adulterants]
The Food Safety and Standards Authority of India (FSSAI) is certainly aware of the problem and prescribes a method to detect lead chromate in turmeric.
A quick search using the terms “turmeric” and “lead chromate” reveals the following:
| Year From | Year To | Hits |
| 01/01/71 | 31/12/80 | 0 |
| 01/01/81 | 31/12/90 | 0 |
| 01/01/91 | 31/12/95 | 1 |
| 01/01/96 | 31/12/00 | 2 |
| 01/01/01 | 31/12/05 | 33 |
| 01/01/06 | 31/12/10 | 70 |
| 01/01/11 | 31/12/15 | 136 |
So, are we more alert now? Has the problem become more prevalent?
In the news item linked above, it is mentioned that it is “conventional” to use lead chromate. Surely not–must be after those pesky inorganic chemicals made their way across the world following the world wars…(see the legend to the lead chromate picture above)
How far back do “conventions” and “traditions” have to go before being called that — one generation?
Bits of history: Chromium the metal, “a thoroughly modern metal,” has been known only since 1797. Different chromium salts were commonly used in painting, but it was supposedly in early 1800s that lead chromate made its appearance.
The story about inorganic dyes and a German connection starting in the last part of the 19th century is well known.
And so on to the Victorian era, when (poisonous) chemicals were added to sweets to make them brightly coloured — lead chromate for yellow, vermilion (mercury salt) for red, copper acetate (verdigris) for green.
In an interesting twist, turmeric (and lead chromate) was detected as an adulterant of custard powder in the 1850s:
| Product | Adulterants [bulk] | Adulterants [colour, taste, smell] |
| Custard powders | Wheat, potato and rice flour | Lead chromate, turmeric to enhance the yellow colour |
So it’s no wonder that lead chromate made its way to the preparation of the humble, ubiquitous turmeric. There must be “conventions” that went back before the 1800’s — or are currently used in small scale production. Processing of turmeric in Chhattisgarh, with or without cow dung and nary a mention of lead chromate, is described in this thesis from Indira Gandhi Krishi Vidyalaya, Raipur (2015)
**When, and where, did the addition of lead chromate to turmeric start? How far did it spread? How find out? ICAR records? Wealth of India? Trade records? Grandparents, diaries, letters?