Urinary excretion half life of trichloroacetic acid as a biomarker of exposure to chlorinated drinking water disinfection by-products.

AIMS: To measure accurately urinary elimination half life of trichloroacetic acid (TCAA). METHODS: A longitudinal pilot exposure/intervention study measured the elimination half life of TCAA in urine. Beverage consumption was limited to a public water supply and bottled water of known TCAA concentration, and ingestion volume was managed. The five participants limited fluid consumption to only the water provided. Consumption journals were kept by each participant and their daily first morning urine (FMU) samples were analysed for TCAA and creatinine. TCAA elimination half life curves were generated from a two week washout period using TCAA-free bottled water. RESULTS: Individual elimination half lives ranged from 2.1 to 6.3 days, for single compartment exponential decay, the model which fit the data. CONCLUSION: Urinary TCAA is persistent enough to be viable as a biomarker of medium term (days) exposure to drinking water TCAA ingestion within a range of realistic concentrations.

Marriage as a stage in the family life cycle.

The life cycle of a family goes through well recognized developmental stages, each of which causes some disruption. At certain stages, preventive intervention by the family physician would be most fruitful. The transition to marriage is a case in point. Knowing the tasks of this stage can help the family physician anticipate any problems, particularly ones which may affect health. Research into the effects of education for marriage has shown that such education helps couples resolve conflicts constructively. Research is now focusing on the next stage of family development: the birth of the first child.