This site is intended for healthcare professionals

Go to /sign-in page

You can view 5 more pages before signing in


Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

Authoring team

Calabash Chalk (Calabar stone, La Craie, Argile, Nzu, Mabele) is traditionally consumed by the Nigerian and wider west African community (and some Asian women) as a remedy for morning sickness.

  • samples of chalk analysed by the Food Standards Agency (FSA) have been found to contain high concentrations of lead
  • consumption of this product would result in an undesirable increase in lead intakes. At the highest lead levels found, women taking 60g a day of the most contaminated product would exceed the safety guideline for lead 4.5 fold, before taking into account any additional exposure from other sources
  • exposure to lead may result in a number of harmful effects, and the developing child is particularly at risk of effects on the nervous system. Studies have shown that prolonged exposure to elevated levels of lead can impair intellectual performance in children
  • patients consuming the product should be advised that:
    • consuming Calabash chalk will increase lead intakes which is undesirable
    • pregnant and breastfeeding women should stop Calabash chalk immediately because exposure to high levels of lead poses a risk to the mental development of their developing foetus and child
    • women who are breastfeeding and who have been taking Calabash chalk should not stop breastfeeding. The transfer of lead into breast milk is low, and the benefits of breastfeeding outweigh the risks. Breastfeeding is accepted as the best form of nutrition for infants to ensure a good start in life. Breastfeeding confers significant short and long term health benefits for both mother and infants beyond the period of breastfeeding itself
    • once consumption of the chalk is stopped the levels of lead in the body will gradually return to normal


  1. Message from Chief Medical Officer, Department of Health (15th October 2002). CEM/CMO/2002/13



Create an account to add page annotations

Add information to this page that would be handy to have on hand during a consultation, such as a web address or phone number. This information will always be displayed when you visit this page