Testing for X-Ray Contrast Agents
X-ray contrast fluids are used to visualize soft tissue such as intestines, kidneys and blood vessels. There are different types of contrast agents used, including barium suspension, water-soluble iodinated contrast fluids, oil-based iodine contrast fluids and contrast fluids for MRI examinations and ultrasounds.
X-ray contrast agents are excreted via urine and faeces. Hospitals are a major contributor to the levels found in urban waste water. Like medicines, these substances often fail to be completely removed in sewage treatment plants as they are highly soluble and do not biodegrade easily. A considerable amount still enters surface water even after treatment.