Here, we discuss the results of applying this protocol in four example studies. We also conducted literature research to develop a detailed survey about potentially important sources of inorganic arsenic exposures for impacted participants. This is a more health-protective approach than using the existing guidance value of 50 μg/L for total arsenic, while still practical in focusing on the most highly exposed participants for required follow-up. We use 20 µg/L total urinary arsenic to identify urine samples for speciation to ensure that all samples with potentially elevated inorganic arsenic are tested. Any participants with urinary inorganic arsenic at or above 20 µg/L are considered to have elevated levels. statistically determined a “cut-point” of 20 µg/L for urinary inorganic arsenic, which we selected as the LOC for inorganic arsenic. We did not identify an established LOC for urinary inorganic arsenic in the general population, nor an applicable urinary threshold for the toxic effects of inorganic arsenic from the scientific literature. We adopted this value as our program’s LOC for total urinary arsenic. The Centers for Disease Control and Prevention (CDC) established a case definition for inorganic arsenic poisoning, which recommends speciation of urine samples with total arsenic levels > 50 μg/L but does not address inorganic arsenic levels. Inorganic arsenic has been detected in some groundwater sources, public drinking water, and cropland soils in California, making it an ongoing public health concern for the state. Human exposure to inorganic arsenic is also linked with other health effects, such as cardiovascular disease and neurotoxicity. Inorganic arsenic compounds are listed under California’s Proposition 65 (Title 27, California Code of Regulations, § 27001) as known to cause cancer and reproductive toxicity (developmental endpoint). This protocol fills a gap in the clinical literature by providing a more health-protective approach to identify individuals with elevated urinary inorganic arsenic and help determine potentially significant exposure sources. Conclusions: Of 48 participants with elevated inorganic arsenic, 27 would have been missed if we had used the previously published threshold of 50 µg/L total arsenic to identify urine samples for speciation. Consumption of rice and rice-based products was the most commonly identified potential source of inorganic arsenic exposure. Results: 48 participants in the four studies had elevated urinary inorganic arsenic levels. We illustrate the protocol in four Biomonitoring California studies, which collected samples from 2010–2013 in locations across the state. Participants with elevated inorganic arsenic were notified of their level and invited to participate in a telephone survey to help determine possible exposure sources. Methods: We selected 20 μg/L as the level of concern for urinary inorganic arsenic samples with total arsenic ≥20 μg/L were speciated. This can be achieved by using GNSS signals to measure and observe changes in the environment.Objectives: to develop and implement a follow-up protocol for Biomonitoring California study participants with elevated levels of urinary arsenic, particularly inorganic forms. From such a definition, what exactly does the term “monitoring” mean within an environmental perspective? Is it synonymous to measuring or observing? A sound definition of monitoring is essential at this point so as to clearly understand the theme of this book, which intents to highlight the uses of GNSS (Global Navigation Satellite Systems) satellites, which have at times been largely regarded as military assets, to monitor the environment. This entails objective observations that produce sound data, which in turn provide valuable information that is useful, e.g., in supporting the protection of public water supplies, hazardous, non-hazardous, and radioactive waste management, natural resource protection and management, weather forecasting, and global climate change (Artiola et al, Environmental monitoring and characterization, 2004, ) studies. Environmental monitoring has been defined as the observation and study of the environment. © Springer International Publishing AG 2018.
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