Patrick J. Parsons
Postdoctoral training: National Institutes of Health, Bethesda, MD
PhD University of London, England
Dr. Parsons’ research investigates how trace elements affect human health and develops new technologies and tools to measure internal (biomonitoring) and external exposures. The goal of this research is to provide better insights into what is now called the “exposome”. According to the CDC (link is external), the exposome can be defined as “the measure of all the exposures of an individual in a lifetime and how those exposures relate to health.” Each person has a unique exposome, which begins before birth, and continues throughout life with exposures from the environment, diet, lifestyle, etc., interacting with our own unique genetics and physiology. Understanding how trace elements may impact the exposome is important – from the nutritional role of the essential elements, e.g., Cu, Se and Zn, to assessing exposure to non-essential toxic elements such as Pb, Cd, Hg and As.
To support such studies, Dr. Parsons’ laboratory has developed specialized techniques for measuring trace elements at extremely low levels in human tissues and body fluids, as well as in food and environmental matrices, using state-of-the-art analytical techniques based on atomic spectrometry. The laboratory has developed and validated new methods for human biomonitoring based on inorganic mass spectrometry. Trace element analysis at the µg/L to ng/L range is carried by inductively coupled plasma-mass spectrometry (ICP-MS) and graphite furnace atomic absorption spectrometry (GFAAS). Class 100 Clean Rooms are required to ensure contamination is minimized. The laboratory is well equipped with 6 Perkin Elmer and 3 Thermo quadrupole ICP-MS instruments, each having either collision cell (CC) and/or dynamic reaction cell (DRC) technology. Additionally, the laboratory has an Agilent 8800 tandem ICP-MS/MS, and a Thermo Element 2 Sector Field ICP-MS that is used to measure isotope ratios and elements with polyatomic interferences that are not easily resolved by a single quadrupole mass analyzer.
Recent research supported by NIEHS has focused on producing well-characterized bone reference materials certified for lead content that can be used to validate techniques based on GFAAS and ICP-MS, as well as K-shell X-ray fluorescence (XRF) spectrometry that is used for non-invasive, in vivo bone lead measurements. Although the total elemental content is useful, speciation methods can provide a much more detailed picture of how some trace elements behave. The lab has been working with the US National Institute for Standards and Technology (NIST) and the CDC on the speciation of Hg in blood that can distinguish and quantitate methylmercury, ethylmercury and inorganic Hg. The method is based on coupling GC to ICP-MS with stable isotope dilution analysis. In a similar manner, the lab can analyze human urine for up to five arsenic species by coupling LC to ICP-MS. In another collaboration with NIST, the laboratory produced and helped certify SRM 955c Toxic Metals in Caprine Blood.
The Parsons’ laboratory has an on-going collaboration with X-Ray Optical Systems (XOS, East Greenbush) using new instruments based on monochromatic XRF. One project involves assessing environmental exposure to Pb, As, and Hg among ethnic Chinese living in upstate NY, supported by NIEHS. Dr. Parsons is also interested in studying the physiologic distribution of trace elements in bone, teeth and brain samples using Laser Ablation coupled to ICP-MS, with recent work focusing on developing calibration materials for quantification. Other research projects involve collaborations with investigators at the Johns Hopkins Bloomberg School of Public Health, Mt Sinai School of Medicine, NICHD, SUNY Oswego, the University at Albany, and the University of Cincinnati. The Parsons’ lab has a long standing collaboration and student exchange program with the trace elements group at the Universidade de São Paulo – Ribeirão Preto, Brasil. In addition to externally funded research studies, the laboratory also operates a biomonitoring proficiency testing program for trace elements. Well-characterized blood, serum and urine reference materials are developed and certified for trace element content.
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