Levels of tin and organotin compounds in human urine samples from Iowa, United States

Abstract

Exposure to tin in the general US population is near ubiquitous, as determined using urinary tin levels measured by inductively coupled plasma mass spectrometry (ICP-MS). Urinary tin levels are associated with chronic health outcomes, such as diabetes; however, it is unclear if these associations are due to the presence of inorganic and organic forms of tin in urine. To address this knowledge gap, levels of total tin and several organotin compounds (OTCs) were measured in convenience urine samples from pregnant women and adults from Iowa, United States. Total tin and OTC levels in urine samples were quantified using ICP-MS and gas chromatography with pulsed flame photometric detection (GC-PFPD), respectively. ICP-MS detected tin in almost all urine samples from both study populations. Low levels of dibutyltin were detected in two out of fifty human urine samples. Importantly, storage of urine samples in plastic containers, but not HNO₃-pretreated glass vials drastically reduced the recoveries of OTCs, in particular, tributyltin. Although their detection frequency is low, exposures to OTC should be considered when studying associations between human exposures to tin compounds and adverse health outcomes; however, urinary OTC levels measured in banked urine samples may not be suitable as biomarkers of OTC exposure.

Keywords:

• Dibutyltin
• inorganic tin
• monobutyltin
• organotin speciation
• sample storage
• tetrabutyltin
• tributyltin
• urinary tin

Acknowledgments

The findings and conclusions in this manuscript are those of the authors and do not necessarily represent the views of the National Institute of Environmental Health Sciences/National Institutes of Health.

Additional information

Funding

This work was supported by the National Institute of Environmental Health Sciences/National Institutes of Health [grant number P30 ES005605].