A study on the different routes of absorption of chloroform A team with the public health research unit at CHUQ undertook a two-part study to estimate the combined effect of all routes of absorption of chloroform. First, under actual exposure conditions, the researchers set out to measure the internal chloroform doses resulting from showers and baths taken by adults and children in Great Quebec City municipalities that get their drinking water from the St Lawrence or one of its main tributaries. Then, based on the internal doses obtained, the research team designed a health risk analysis model for assessing chloroform exposure linked to residential water. For the group of participants, the researchers measured the chloroform concentration in exhaled air before and immediately after the bath or shower, as well as 15 and 30 minutes later. The participants had to breathe into a bag, and the trapped air was then analysed to determine the chloroform concentration.
Most chloroform is eliminated by the body via the lungs.
This reading thus constitutes a biological indicator of exposure to chloroform. The reading taken before the bath or shower provided a baseline internal dose for the participants. The difference between the chloroform concentration expelled before and then after the bath or shower indicated the internal dose associated with the shower or bath. Similarly, the difference between the concentrations measured 15 and then 30 minutes later and the baseline reading were used to determine the residual internal doses for those periods. The internal doses recorded were used to design a model that was subsequently employed in estimating the cancer risk for all routes of exposure to chloroform contained in the drinking water of dwellings.