Factors influencing uncertainties of in vivo bone lead measurement using a (109)Cd K X-ray fluorescence clover leaf geometry detector system
- DOI
- Language of the publication
- English
- Date
- 2014-12-01
- Type
- Article
- Author(s)
- Behinaein, Sepideh
- Chettle, David R.
- Marro, Leonora
- Malowany, Morie
- Fisher, Mandy
- Fleming, David E. B.
- Healey, Norm
- Inskip, Mike
- Arbuckle, Tye E.
- McNeill, Fiona E.
- Publisher
- Royal Society of Chemistry
Abstract
A (109)Cd K X-ray fluorescence (KXRF) measurement system consisting of four detectors in clover-leaf geometry is a non-invasive, low-radiation-dose method of measuring bone lead concentration. Its high precision in estimating the bone lead content makes it a promising tool for the determination of the low levels of lead currently found in the general population. After developing the clover-leaf geometry system, the system was used for the first time in a major survey in 2008 to measure the lead levels of 497 smelter employees (an occupationally exposed group with high lead levels). Since the delivered effective dose of the bone lead system in clover-leaf geometry is small (on the order of nSv), the technique can be used to measure the bone lead of sensitive populations such as the elderly and children. This detector system was used from 2009 to 2011, in a pilot study that measured the bone lead concentration of 263 environmentally exposed individuals (termed the EG group) residing in Toronto, Ontario, Canada. In this paper, the factors that influence uncertainties in lead content in tibia (cortical bone) and calcaneus (trabecular bone) are discussed based on gender, age, and body mass index (BMI) by using analysis of variance (ANOVA) and multiple linear regression models. Results from the two study groups (the EG group versus the occupationally exposed smelter employees) are compared where appropriate (i.e. for males older than 20). Results from univariate analyses showed that females have higher tibia uncertainty compared to males. We observed significant differences for both calcaneus and tibia uncertainty measures (p < 0.0005) among different age groups, where the uncertainties were highest in the lowest age group (<11 years). Lastly, and perhaps most significantly, we found that the product of source activity and measurement time influenced the precision of measurements greatly, and that this factor alone could account for the higher uncertainties observed for the male cohort of the EG group versus the smelter employees.
Plain language summary
Health Canada helps to protect the health of Canadians by assessing and managing the health risks associated with exposure to environmental contaminants such as lead. Blood lead levels in Canadians have declined over the past 30 years as a result of measures to reduce exposure, making them amongst the lowest in the world. However, lead is still widely detected in Canadians, and evidence shows that even low levels can cause adverse health effects; thus, research and monitoring continues to support health impact assessments of lead. Lead can be stored in the bone for long periods and subsequently be released back into the blood over time, affecting blood lead levels. This means that blood lead levels reflect both recent exposure to lead in the environment, as well as long-term exposure. Furthermore, lead stored in bone is released during pregnancy as a result of physiological changes, increasing the levels to which a developing baby may be exposed. Thus, it is important to be able to accurately measure levels of lead in bone as well as in blood in order to determine whether there are any associated health risks. In this study, bone lead levels were measured in 263 men, women and children from Toronto, Canada between September 2009 and January 2011 in order to assess the feasibility of monitoring lead levels in a population survey and to assess the reliability of the measurement technique. These volunteers ranged in age from 1-82 years and were compared to an occupationally exposed group of lead smelter workers. Bone lead levels were measured using109Cd K x-ray fluorescence (KXRF) – a measurement technique that is rapid, safe and painless. Factors that influence uncertainties in bone lead measurements, including gender, age, and body mass index (BMI), were assessed. The results of this study will be helpful in designing approaches to improve the precision of bone lead measurements to inform assessments of the efficacy of measures to reduce lead exposure.
Subject
- Health,
- Health and safety