Chlorine from water and salt during cooking could create toxic molecules

Chlorination of tap water brought a revolution in the prevention of infectious diseases. At the waterworks either chlorine or hypochlorites are added to the water, or for the disinfection chlorine and ammonia is used which react together to create chloramine. Chlorine is highly reactive and disrupts vital organic molecules in cells. Thus they reliably exterminate all germs which got into the water.

The reaction of chlorine with other substances present in the water is a varied range of compounds that are still only partially explored. Their effects on the human body is the big unknown. Chinese scientists published in the scientific journal Water Research the results of analysis of substances formed during cooking of food in the chlorinated water.

Scientists warmed chlorinated water blended with wheat flour and iodized table salt. Iodine from the salt is reacted with chlorine from the water on hypoiodous acid.

 

This in itself isn't cause for concern, but the acid can then react with the food and other organic matter in the tap water to create cooking iodinated disinfection byproducts (I-DBPs) - molecules that are almost completely new to researchers. For the new study, the team identified some molecules and tested their toxicity.
Some of the substances formed during the cooking of food in chlorinated water are apparently harmless. Others however have toxic effects.

"Considering that these molecules could have an adverse effect on our health, we need to study them more to determine exactly what effects they might have," said Dr. Yang Pan, one of the study's authors and Assistant Professor at Nanjing University.
 

The results show that the formation of potentially hazardous substances can significantly reduce the cooking conditions. It is generally recommended to cook at lower temperatures, thus avoiding these effects e.g. cooking by using pressure cookers, and cooking for shorter periods. The risk of potentially toxic substances is lower in the disinfected water with chlorine or hypochlorites in comparison with chloramine disinfection. It depends also on the form in which iodine is added to table salt. There is a lower risk of toxic substances when using salt with the addition of potassium iodate than the salt, wherein iodine is supplemented in the form of potassium iodide.
 

It might help add salt after the meal is cooked or get some good quality home water filter.
 

More information: Yang Pan et al. Identification, toxicity and control of iodinated disinfection byproducts in cooking with simulated chlor(am)inated tap water and iodized table salt, Water Research (2016). DOI: 10.1016/j.watres.2015.10.002