Toddlers less able to detox arsenic than infants.

Feb 06, 2009

Fangstrom B, J Hamadani, B Nermell, M Grander, B Palm and M Vahter. 2009. Impaired arsenic metabolism in children during weaning. Toxicology and Applied Pharmacology doi:10.1016/j.taap.2008.12.019.

Synopsis by Abby D. Benninghoff, Ph.D.

As babies grow into toddlers, their ability to alter arsenic into less harmful forms changes, leaving them less able to get rid of the cancer-causing metal and perhaps, more susceptible to its effects.

The results of this study of 18-month-old Bangladeshi children show for the first time that arsenic metabolism changes as infants grow into toddlers and replace breastfeeding with eating food and drinking water. The children face a double whammy: they are less able to detoxify the poison at a time when their exposure through food and water is most likely increasing.

Levels of arsenic in drinking water and the soil are particularly high in Bangladesh. More than half the wells have concentrations higher than 10 micrograms per liter (the international standard set by the World Health Organization). 

Arsenic is a naturally-occurring metal found worldwide. In humans, it can cause cancer and can affect pregnancies and development. The metal is more toxic in its orginal form than its main metabolized forms, which are excreted in urine.

Children may be exposed to arsenic in the womb, by their mother's milk or via their water and diet after weaning.  During pregnancy and breastfeeding, though, the mother's strong metabolism helps get rid of most of the harmful form of arsenic. 

In this study, researchers measured levels of arsenic and two breakdown products, methylarsonic acid (MA) and dimethylarsinic acid (DMA), in the urine of 18-month old children. They compared their levels to those found in mothers and in a group of 3-month-old, breastfeeding babies.

When compared to the infants, the relative amounts of the two metabolites changed for the worse in the 18-month-old toddlers.  The higher amounts of MA found indicate that the older children were less able to rid their body of arsenic. 

These children may be more susceptible to the harmful effects of arsenic when their exposures increase as they start to drink water and eat solid food.