Erika Mitchell | Norwich University (original) (raw)

Papers by Erika Mitchell

PLOS ONE

Evidence-based public health policy often comes years or decades after the underlying scientific ... more Evidence-based public health policy often comes years or decades after the underlying scientific breakthrough. The World Health Organization’s (WHO’s) provisional 10 μg/L arsenic (As) drinking water guideline was set in 1993 based on “analytical achievability.” In 2011, an additional proviso of “treatment performance” was added; a health-based risk assessment would lead to a lower and more protective guideline. Since the WHO does not require United Nations member states to submit copies of national drinking water regulations, there is no complete database of national drinking water standards or guidelines. In this study, we collated and analyzed all drinking water regulations for As from national governments worldwide. We found regulations for 176 countries. Of these countries, 136 have drinking water regulations that specify 10 μg/L As or less, while 40 have regulations that allow more than 10 μg/L of As; we could not find any evidence of regulations for 19 countries. The number of...

Environmental Health Perspectives, 2002

Geographic, Demographic, and Economic Overview of Bangladesh The People's Republic of Bangladesh ... more Geographic, Demographic, and Economic Overview of Bangladesh The People's Republic of Bangladesh is a developing country overburdened with an enormous population, severe poverty, common illiteracy, and frequent natural disasters. It is located at one of the largest river deltas in the world: The Ganges, Brahmaputra, and Meghna rivers flow through Bangladesh to the Bay of Bengal. Very little of the country is more than 12 m (40 feet) above sea level, and in a normal monsoon season one-third of its cultivated land is flooded (1). Bangladesh has 127 million people (2) living on 144,000 km 2 (1); this would be equivalent to one-half the population of the United States living in an area the size of Wisconsin. The infant mortality rate is 58 per 1,000 live births (2). There is one doctor per 5,200 people; by comparison, the United Kingdom has one doctor per 650 people (1). The adult literacy rate is 63% for men and 48% for women. The average annual income is equivalent to US$370 per capita (2). The life expectancy is 55 years (1). Bangladesh is an agricultural country with the vast majority of its people involved in food production. Rice is grown during the rainy season and is used primarily for domestic consumption. In irrigated areas, a second rice crop is possible, followed by wheat and vegetables in the short, dry winter from November to February. Bangladesh is the world's leading producer of jute, a strong natural fiber used in the carpet and sacking industries. The principal exports of Bangladesh from largest to smallest are garments, jute and its products, shellfish, tea, and leather (1).

Journal of Environmental and Public Health, 2022

Residents of Nepal’s Kathmandu Valley draw drinking water from tube wells, dug wells, and stone s... more Residents of Nepal’s Kathmandu Valley draw drinking water from tube wells, dug wells, and stone spouts, all of which have been reported to have serious water quality issues. In this study, we analyzed drinking water samples from 35 tube wells, dug wells, stone spouts, and municipal tap water for bacterial and chemical contaminants, including total and fecal coliform, aluminum, arsenic, barium, beryllium, boron, cadmium, cobalt, chromium, copper, fluoride, iron, mercury, manganese, molybdenum, nickel, lead, antimony, selenium, thallium, uranium, vanadium, and zinc. We also asked a sampling of households who used these specific water sources to rate the taste of their water, list any waterborne diseases they were aware of, and share basic health information about household members. This survey provided us with information from 146 households and 603 individuals. We found widespread bacterial contamination of water sources, with 94% of sources having detectable total or fecal coliform....

BackgroundAlthough manganese (Mn) is an essential nutrient, recent research has revealed that exc... more BackgroundAlthough manganese (Mn) is an essential nutrient, recent research has revealed that excess Mn in early childhood may have adverse effects on neurodevelopment.MethodsWe estimated daily total Mn intake due to breast milk at average body weights by reviewing reported concentrations of breast milk Mn and measurements of body weight and breast milk intake at 3 weeks, 4.25 months, 7 months, and 18 months. We compared these figures to the Mn content measured in 44 infant, follow-up, and toddler formulas purchased in the United States and France. We calculated Mn content of formula products made with ultra-trace elemental analysis grade water (0 µg Mn/L) and with water containing 250 µg Mn/L, a concentration which is relatively high but less than the World Health Organization Health-based value of 400 µg Mn/L or the United States Environmental Protection Agency Health Advisory of 350 µg Mn/L.ResultsEstimated mean daily Mn intake from breast milk ranged from 1.2 µg Mn/kg/day (3 wee...

Environmental …, 2012

Background: The World Health Organization (WHO) released the 4th edition of Guidelines for Drinki... more Background: The World Health Organization (WHO) released the 4th edition of Guidelines for Drinking-water Quality in July, 2011. In this edition, the 400 µg/L drinking water guideline for manganese (Mn) was discontinued with the assertion that since “this health-based ...

PLOS ONE, 2019

Exposure to high levels of manganese (Mn) in children has recently been associated with adverse n... more Exposure to high levels of manganese (Mn) in children has recently been associated with adverse neurodevelopmental effects. Current infant formula regulations for Mn content were set between 1981 (United States), 2006 (European Union, France), and 2007 (Codex Alimentarius) prior to the publication of much of the growing body of research on the developmental neurotoxicity of Mn. In this study, we sought to measure the concentrations of Mn in some infant formulas and young child nutritional beverages available on the United States (US) and French markets using ion beam analysis by particle induced X-ray emission (PIXE) spectrometry and then compare the analytical results to concentrations reported in the literature for breast milk and applicable infant formula regulations and guidelines. We were particularly interested in measuring Mn concentrations in product types for which there is very little data from previous surveys, especially soy-based, rice-based, goat-milk based, chocolate-flavored, and nutritional beverages for young children that are not regulated as infant or follow-on formulas (e.g. "toddler formulas" and "toddler powders"). We purchased 44 infant formulas and young child nutritional beverage products in the US and France with varying protein sources (cow-milk, goat-milk, soy, rice) labelled for birth to 3 years. We selected these samples using maximum variation sampling to explore market extremes to facilitate comparisons to regulatory limits. Since this sampling method is non-probabilistic, other inferences cannot be made beyond this set of samples to the overall markets. We used ion beam analysis to measure the concentrations of Mn in each product. The range of measured Mn concentrations in the products is 160-2,800 μg/L, substantially higher than the 3-6 μg/L mean Mn concentration reported in human breast milk. All products satisfied national and Codex Alimentarius Commission (CAC) international standards for minimum Mn content in infant formulas; however, 7/25 of the products purchased in the US exceeded the CAC Guidance Upper Level of 100 μg Mn/kcal for infant formula.

Linguistic Inquiry, 1991

... Erika Mitchell, (1) [TPNP [TP T[NegP Neg [AgrP Agr [vp (Adv) V]]]] Cornell University Pollock... more ... Erika Mitchell, (1) [TPNP [TP T[NegP Neg [AgrP Agr [vp (Adv) V]]]] Cornell University Pollock presents syntactic reasons for ordering AgrP within TP based on verb movement phenomena. He does this with the proviso that this ordering is not meant to be universal, but in-stead is ...

Abstract: Cabbage (Brassica oleracea) seeds were germinated and grown for 35 days in an organic s... more Abstract: Cabbage (Brassica oleracea) seeds were germinated and grown for 35 days in an organic standard substrate contained in either plastic, peat, paper, or newspaper containers to determine whether the container material might affect growth. Days to emergence, days to first leaf, and developmental morphological traits and physiological characteristics were monitored. Differences in evaporation and pH of water in contact with the containers were measured in separate experiments. Evaporation was lowest from plastic and highest from peat containers, while pH was lowest with water in contact with peat containers. Plant growth was fastest and most robust in plastic containers as demonstrated by their shoot height, stem diameter, and root and shoot dry weights. Seedlings grown in newspaper containers presented exceedingly poor growth and showed signs of stress.

International Journal of Applied Mathematics and Theoretical Physics

Calibration curves are commonly used for quantitative analysis in analytical chemistry to calcula... more Calibration curves are commonly used for quantitative analysis in analytical chemistry to calculate the concentrations of chemicals in samples. Typically, the concentration of the analyte, the chemical being quantified, is the independent variable and is plotted on the x-axis. The detector response, the reading from the instrument, is the dependent variable and is plotted on the y-axis. A calibration curve is made by plotting the known concentration of analyte versus the detector response. After a calibration curve is made, the unknown concentration of analyte in any sample is calculated from its detector response. Unfortunately, there is no standard procedure for objectively testing the fit of calibration curves in analytical chemistry. For example, the World Health Organization (WHO) and the United States Environmental Protection Agency (U.S. EPA) do not provide guidance for testing the linearity or curvature of calibration curves. Moreover, this important topic is not broached in at least 5 of the leading analytical chemistry textbooks. However, there is a simple and effective way to fix this deficiency. In this paper, the use of polynomial regression to objectively test the fit of calibration curves in drinking water analysis is demonstrated. Polynomial regression was used to test the linearity of a representative calibration curve for the spectrophotometric determination of arsenic in drinking water by the arsenomolybdate method. And polynomial regression was used to test the curvature of a representative calibration curve for the determination of arsenic in drinking water by graphite furnace atomic absorption spectroscopy. Microsoft® Excel® 2010 and 2016, MiniTab® 17.2.1, and RStudio® 0.99.441 were used to calculate these calibration curves; in all cases, the calibration curves from these 3 programs agreed with each other to at least 3 significant figures.

International Journal of Applied Mathematics and Theoretical Physics

The equation promulgated by 40 Code of Federal Regulations (CFR) to calculate method detection li... more The equation promulgated by 40 Code of Federal Regulations (CFR) to calculate method detection limit (MDL) and used since 1981 in the United States and other countries to protect public health and the environment is incorrect. As a result, toxic chemicals in a large number of air, food, water, wastes, and other environmental samples may in fact be present at measurable concentrations even though they are currently being reported as "not detected". That is, the air we breathe, the food we eat, and the water and other liquids we drink may have measurable concentrations of toxic chemicals, despite being reported as not detected and assumed to be absent. Furthermore, many chemicals, such as arsenic (As) in drinking water, are so toxic that they cannot be measured to safe levels and the allowable limits must be set at the lowest reportable concentrations. As a result, the allowable limits for some extremely toxic chemicals may be incorrectly set too high. Therefore, the consequences of this error pose a risk to public health and the environment. The sources of this error are explained and two improved ways of calculating method detection limit are presented.

PLOS ONE

Spectrophotometers are commonly used to measure the concentrations of a wide variety of analytes ... more Spectrophotometers are commonly used to measure the concentrations of a wide variety of analytes in drinking water and other matrixes; however, many laboratories with limited resources cannot afford to buy these very useful instruments. To meet this need, an accurate, precise, and affordable light emitting diode (LED) spectrophotometer was designed and built using best engineering practices and modern circuit design. The cost and performance of this LED spectrophotometer was compared against 4 common commercial spectrophotometers. More specifically, the performance of these spectrophotometers was evaluated from the upper limits of linear range, upper limits of operational range, calibration sensitivities, R 2 values, precisions of standards, estimated limits of detection, and percent calibration check standard recoveries for the determinations of iron (Fe), manganese (Mn), and fluoride (F −) in drinking water. This evaluation was done in the United States (U.S.

Applications in Plant Sciences

The Polypodium vulgare complex (Polypodiaceae) is a group of Northern Hemisphere fern species onc... more The Polypodium vulgare complex (Polypodiaceae) is a group of Northern Hemisphere fern species once recognized as a single species, P. vulgare L. During the 20th century, this single species was eventually split into 16 species and numerous sterile hybrids based on evidence from cytological, hybridization, geographical, and morphological studies (e.g., Haufler et al., 1995). Ten of these species have been described as diploids, and they form four lineages that are supported by multiple molecular markers and morphological evidence. Six more species are considered allopolyploids, derived from hybridization between two or more diploid progenitor species, likely within the last 15 million years (Bryan and Soltis, 1987; Haufler et al., 1995; Sigel et al., 2014). The patterns and mechanisms of evolution at the population level are not well understood, and no microsatellite markers have been previously developed for the P. vulgare complex, impeding progress toward understanding these recently derived species. One primarily North American lineage ('Clade A' in Sigel et al., 2014) is composed of three diploid species (P. appalachianum Haufler & Windham, P. amorphum Suksd., and P. sibiricum Sipliv.) and two allopolyploid species (P. saximontanum Windham and P. virginianum L.). The Appalachian rockcap fern, P. appalachianum, is distributed across the Appalachian Mountains, from Ontario to northern Georgia, and is a diploid (2n = 74; Haufler and Wang, 1991). The common rockcap fern, P. virginianum, is a tetraploid (2n = 148; Haufler et al., 1993) derived from hybridization between P. appalachianum and P. sibiricum. Polypodium virginianum overlaps the distribution of P. appalachianum in the Appalachian Mountains and is also found in the Ozark Mountains and the Great Lakes region (Haufler and Wang, 1991). Polypodium amorphum and P. saximontanum occur in the western United States, whereas P. sibiricum is distributed across northern Canada into Alaska and northern Asia. All species in this lineage tend to be found on rocky outcrops or cliffs, and P. appalachianum and P. virginianum are nearly morphologically indistinguishable where they co-occur (Haufler et al., 1993). Development of microsatellite markers focused on the diploid P. appalachianum will yield a novel genetic tool for use in evolutionary studies within the P. appalachianum-P. virginianum complex, within the broader Clade A complex, and possibly across the P. vulgare complex.

Cogent Food & Agriculture

Cabbage (Brassica oleracea) seeds were germinated and grown for 35 days in an organic standard su... more Cabbage (Brassica oleracea) seeds were germinated and grown for 35 days in an organic standard substrate contained in either plastic, peat, paper, or newspaper containers to determine whether the container material might affect growth. Days to emergence, days to first leaf, and developmental morphological traits and physiological characteristics were monitored. Differences in evaporation and pH of water in contact with the containers were measured in separate experiments. Evaporation was lowest from plastic and highest from peat containers, while pH was lowest with water in contact with peat containers. Plant growth was fastest and most robust in plastic containers as demonstrated by their shoot height, stem diameter, and root and shoot dry weights. Seedlings grown in newspaper containers presented exceedingly poor growth and showed signs of stress.

Calibration curves are commonly used for quantitative analysis in analytical chemistry to calcula... more Calibration curves are commonly used for quantitative analysis in analytical chemistry to calculate the concentrations of chemicals in samples. Typically, the concentration of the analyte, the chemical being quantified, is the independent variable and is plotted on the x-axis. The detector response, the reading from the instrument, is the dependent variable and is plotted on the y-axis. A calibration curve is made by plotting the known concentration of analyte versus the detector response. After a calibration curve is made, the unknown concentration of analyte in any sample is calculated from its detector response. Unfortunately, there is no standard procedure for objectively testing the fit of calibration curves in analytical chemistry. For example, the World Health Organization (WHO) and the United States Environmental Protection Agency (U.S. EPA) do not provide guidance for testing the linearity or curvature of calibration curves. Moreover, this important topic is not broached in...

The equation promulgated by 40 Code of Federal Regulations (CFR) to calculate method detection li... more The equation promulgated by 40 Code of Federal Regulations (CFR) to calculate method detection limit (MDL) and used since 1981 in the United States and other countries to protect public health and the environment is incorrect. As a result, toxic chemicals in a large number of air, food, water, wastes, and other environmental samples may in fact be present at measurable concentrations even though they are currently being reported as "not detected". That is, the air we breathe, the food we eat, and the water and other liquids we drink may have measurable concentrations of toxic chemicals, despite being reported as not detected and assumed to be absent. Furthermore, many chemicals, such as arsenic (As) in drinking water, are so toxic that they cannot be measured to safe levels and the allowable limits must be set at the lowest reportable concentrations. As a result, the allowable limits for some extremely toxic chemicals may be incorrectly set too high. Therefore, the consequences of this error pose a risk to public health and the environment. The sources of this error are explained and two improved ways of calculating method detection limit are presented.

Environmental Health, 2015

The World Health Organization (WHO) has established guidelines for drinking-water quality that co... more The World Health Organization (WHO) has established guidelines for drinking-water quality that cover biological and chemical hazards from both natural and anthropogenic sources. In the most recent edition of Guidelines for Drinking-water Quality (2011), the WHO withdrew, suspended, did not establish, or raised guidelines for the inorganic toxic substances manganese, molybdenum, nitrite, aluminum, boron, nickel, uranium, mercury, and selenium. In this paper, we review these changes to the WHO drinking-water guidelines, examining in detail the material presented in the WHO background documents for each of these toxic substances. In some cases, these WHO background documents use literature reviews that do not take into account scientific research published within the last 10 or more years. In addition, there are instances in which standard WHO practices for deriving guidelines are not used; for example, rounding and other mathematical errors are made. According to published meeting reports from the WHO Chemical Aspects Working Group, the WHO has a timetable for revising some of its guidelines for drinking-water quality, but for many of these toxic substances the planned changes are minimal or will be delayed for as long as 5 years. Given the limited nature of the planned WHO revisions to the inorganic toxic substances and the extended timetable for these revisions, we suggest that governments, researchers, and other stakeholders might establish independent recommendations for inorganic toxic substances and possibly other chemicals to proactively protect public health, or at the very least, revert to previous editions of the Guidelines for Drinking-water Quality, which were more protective of public health.

Environmental Health

The World Health Organization (WHO) has established guidelines for drinking-water quality that co... more The World Health Organization (WHO) has established guidelines for drinking-water quality that cover biological and chemical hazards from both natural and anthropogenic sources. In the most recent edition of Guidelines for Drinking-water Quality (2011), the WHO withdrew, suspended, did not establish, or raised guidelines for the inorganic toxic substances manganese, molybdenum, nitrite, aluminum, boron, nickel, uranium, mercury, and selenium. In this paper, we review these changes to the WHO drinking-water guidelines, examining in detail the material presented in the WHO background documents for each of these toxic substances. In some cases, these WHO background documents use literature reviews that do not take into account scientific research published within the last 10 or more years. In addition, there are instances in which standard WHO practices for deriving guidelines are not used; for example, rounding and other mathematical errors are made. According to published meeting reports from the WHO Chemical Aspects Working Group, the WHO has a timetable for revising some of its guidelines for drinking-water quality, but for many of these toxic substances the planned changes are minimal or will be delayed for as long as 5 years. Given the limited nature of the planned WHO revisions to the inorganic toxic substances and the extended timetable for these revisions, we suggest that governments, researchers, and other stakeholders might establish independent recommendations for inorganic toxic substances and possibly other chemicals to proactively protect public health, or at the very least, revert to previous editions of the Guidelines for Drinking-water Quality, which were more protective of public health.

The Science of the total environment, 2015

In South Asia, the technological and societal shift from drinking surface water to groundwater ha... more In South Asia, the technological and societal shift from drinking surface water to groundwater has resulted in a great reduction of acute diseases due to water borne pathogens. However, arsenic and other naturally occurring inorganic toxic substances present in groundwater in the region have been linked to a variety of chronic diseases, including cancers, heart disease, and neurological problems. Due to the highly specific symptoms of chronic arsenic poisoning, arsenic was the first inorganic toxic substance to be noticed at unsafe levels in the groundwater of West Bengal, India and Bangladesh. Subsequently, other inorganic toxic substances, including manganese, uranium, and fluoride have been found at unsafe levels in groundwater in South Asia. While numerous drinking water wells throughout Myanmar have been tested for arsenic, relatively little is known about the concentrations of other inorganic toxic substances in Myanmar groundwater. In this study, we analyzed samples from 18 d...

PLOS ONE

Evidence-based public health policy often comes years or decades after the underlying scientific ... more Evidence-based public health policy often comes years or decades after the underlying scientific breakthrough. The World Health Organization’s (WHO’s) provisional 10 μg/L arsenic (As) drinking water guideline was set in 1993 based on “analytical achievability.” In 2011, an additional proviso of “treatment performance” was added; a health-based risk assessment would lead to a lower and more protective guideline. Since the WHO does not require United Nations member states to submit copies of national drinking water regulations, there is no complete database of national drinking water standards or guidelines. In this study, we collated and analyzed all drinking water regulations for As from national governments worldwide. We found regulations for 176 countries. Of these countries, 136 have drinking water regulations that specify 10 μg/L As or less, while 40 have regulations that allow more than 10 μg/L of As; we could not find any evidence of regulations for 19 countries. The number of...

Environmental Health Perspectives, 2002

Geographic, Demographic, and Economic Overview of Bangladesh The People's Republic of Bangladesh ... more Geographic, Demographic, and Economic Overview of Bangladesh The People's Republic of Bangladesh is a developing country overburdened with an enormous population, severe poverty, common illiteracy, and frequent natural disasters. It is located at one of the largest river deltas in the world: The Ganges, Brahmaputra, and Meghna rivers flow through Bangladesh to the Bay of Bengal. Very little of the country is more than 12 m (40 feet) above sea level, and in a normal monsoon season one-third of its cultivated land is flooded (1). Bangladesh has 127 million people (2) living on 144,000 km 2 (1); this would be equivalent to one-half the population of the United States living in an area the size of Wisconsin. The infant mortality rate is 58 per 1,000 live births (2). There is one doctor per 5,200 people; by comparison, the United Kingdom has one doctor per 650 people (1). The adult literacy rate is 63% for men and 48% for women. The average annual income is equivalent to US$370 per capita (2). The life expectancy is 55 years (1). Bangladesh is an agricultural country with the vast majority of its people involved in food production. Rice is grown during the rainy season and is used primarily for domestic consumption. In irrigated areas, a second rice crop is possible, followed by wheat and vegetables in the short, dry winter from November to February. Bangladesh is the world's leading producer of jute, a strong natural fiber used in the carpet and sacking industries. The principal exports of Bangladesh from largest to smallest are garments, jute and its products, shellfish, tea, and leather (1).

Journal of Environmental and Public Health, 2022

Residents of Nepal’s Kathmandu Valley draw drinking water from tube wells, dug wells, and stone s... more Residents of Nepal’s Kathmandu Valley draw drinking water from tube wells, dug wells, and stone spouts, all of which have been reported to have serious water quality issues. In this study, we analyzed drinking water samples from 35 tube wells, dug wells, stone spouts, and municipal tap water for bacterial and chemical contaminants, including total and fecal coliform, aluminum, arsenic, barium, beryllium, boron, cadmium, cobalt, chromium, copper, fluoride, iron, mercury, manganese, molybdenum, nickel, lead, antimony, selenium, thallium, uranium, vanadium, and zinc. We also asked a sampling of households who used these specific water sources to rate the taste of their water, list any waterborne diseases they were aware of, and share basic health information about household members. This survey provided us with information from 146 households and 603 individuals. We found widespread bacterial contamination of water sources, with 94% of sources having detectable total or fecal coliform....

BackgroundAlthough manganese (Mn) is an essential nutrient, recent research has revealed that exc... more BackgroundAlthough manganese (Mn) is an essential nutrient, recent research has revealed that excess Mn in early childhood may have adverse effects on neurodevelopment.MethodsWe estimated daily total Mn intake due to breast milk at average body weights by reviewing reported concentrations of breast milk Mn and measurements of body weight and breast milk intake at 3 weeks, 4.25 months, 7 months, and 18 months. We compared these figures to the Mn content measured in 44 infant, follow-up, and toddler formulas purchased in the United States and France. We calculated Mn content of formula products made with ultra-trace elemental analysis grade water (0 µg Mn/L) and with water containing 250 µg Mn/L, a concentration which is relatively high but less than the World Health Organization Health-based value of 400 µg Mn/L or the United States Environmental Protection Agency Health Advisory of 350 µg Mn/L.ResultsEstimated mean daily Mn intake from breast milk ranged from 1.2 µg Mn/kg/day (3 wee...

Environmental …, 2012

Background: The World Health Organization (WHO) released the 4th edition of Guidelines for Drinki... more Background: The World Health Organization (WHO) released the 4th edition of Guidelines for Drinking-water Quality in July, 2011. In this edition, the 400 µg/L drinking water guideline for manganese (Mn) was discontinued with the assertion that since “this health-based ...

PLOS ONE, 2019

Exposure to high levels of manganese (Mn) in children has recently been associated with adverse n... more Exposure to high levels of manganese (Mn) in children has recently been associated with adverse neurodevelopmental effects. Current infant formula regulations for Mn content were set between 1981 (United States), 2006 (European Union, France), and 2007 (Codex Alimentarius) prior to the publication of much of the growing body of research on the developmental neurotoxicity of Mn. In this study, we sought to measure the concentrations of Mn in some infant formulas and young child nutritional beverages available on the United States (US) and French markets using ion beam analysis by particle induced X-ray emission (PIXE) spectrometry and then compare the analytical results to concentrations reported in the literature for breast milk and applicable infant formula regulations and guidelines. We were particularly interested in measuring Mn concentrations in product types for which there is very little data from previous surveys, especially soy-based, rice-based, goat-milk based, chocolate-flavored, and nutritional beverages for young children that are not regulated as infant or follow-on formulas (e.g. "toddler formulas" and "toddler powders"). We purchased 44 infant formulas and young child nutritional beverage products in the US and France with varying protein sources (cow-milk, goat-milk, soy, rice) labelled for birth to 3 years. We selected these samples using maximum variation sampling to explore market extremes to facilitate comparisons to regulatory limits. Since this sampling method is non-probabilistic, other inferences cannot be made beyond this set of samples to the overall markets. We used ion beam analysis to measure the concentrations of Mn in each product. The range of measured Mn concentrations in the products is 160-2,800 μg/L, substantially higher than the 3-6 μg/L mean Mn concentration reported in human breast milk. All products satisfied national and Codex Alimentarius Commission (CAC) international standards for minimum Mn content in infant formulas; however, 7/25 of the products purchased in the US exceeded the CAC Guidance Upper Level of 100 μg Mn/kcal for infant formula.

Linguistic Inquiry, 1991

... Erika Mitchell, (1) [TPNP [TP T[NegP Neg [AgrP Agr [vp (Adv) V]]]] Cornell University Pollock... more ... Erika Mitchell, (1) [TPNP [TP T[NegP Neg [AgrP Agr [vp (Adv) V]]]] Cornell University Pollock presents syntactic reasons for ordering AgrP within TP based on verb movement phenomena. He does this with the proviso that this ordering is not meant to be universal, but in-stead is ...

Abstract: Cabbage (Brassica oleracea) seeds were germinated and grown for 35 days in an organic s... more Abstract: Cabbage (Brassica oleracea) seeds were germinated and grown for 35 days in an organic standard substrate contained in either plastic, peat, paper, or newspaper containers to determine whether the container material might affect growth. Days to emergence, days to first leaf, and developmental morphological traits and physiological characteristics were monitored. Differences in evaporation and pH of water in contact with the containers were measured in separate experiments. Evaporation was lowest from plastic and highest from peat containers, while pH was lowest with water in contact with peat containers. Plant growth was fastest and most robust in plastic containers as demonstrated by their shoot height, stem diameter, and root and shoot dry weights. Seedlings grown in newspaper containers presented exceedingly poor growth and showed signs of stress.

International Journal of Applied Mathematics and Theoretical Physics

Calibration curves are commonly used for quantitative analysis in analytical chemistry to calcula... more Calibration curves are commonly used for quantitative analysis in analytical chemistry to calculate the concentrations of chemicals in samples. Typically, the concentration of the analyte, the chemical being quantified, is the independent variable and is plotted on the x-axis. The detector response, the reading from the instrument, is the dependent variable and is plotted on the y-axis. A calibration curve is made by plotting the known concentration of analyte versus the detector response. After a calibration curve is made, the unknown concentration of analyte in any sample is calculated from its detector response. Unfortunately, there is no standard procedure for objectively testing the fit of calibration curves in analytical chemistry. For example, the World Health Organization (WHO) and the United States Environmental Protection Agency (U.S. EPA) do not provide guidance for testing the linearity or curvature of calibration curves. Moreover, this important topic is not broached in at least 5 of the leading analytical chemistry textbooks. However, there is a simple and effective way to fix this deficiency. In this paper, the use of polynomial regression to objectively test the fit of calibration curves in drinking water analysis is demonstrated. Polynomial regression was used to test the linearity of a representative calibration curve for the spectrophotometric determination of arsenic in drinking water by the arsenomolybdate method. And polynomial regression was used to test the curvature of a representative calibration curve for the determination of arsenic in drinking water by graphite furnace atomic absorption spectroscopy. Microsoft® Excel® 2010 and 2016, MiniTab® 17.2.1, and RStudio® 0.99.441 were used to calculate these calibration curves; in all cases, the calibration curves from these 3 programs agreed with each other to at least 3 significant figures.

International Journal of Applied Mathematics and Theoretical Physics

The equation promulgated by 40 Code of Federal Regulations (CFR) to calculate method detection li... more The equation promulgated by 40 Code of Federal Regulations (CFR) to calculate method detection limit (MDL) and used since 1981 in the United States and other countries to protect public health and the environment is incorrect. As a result, toxic chemicals in a large number of air, food, water, wastes, and other environmental samples may in fact be present at measurable concentrations even though they are currently being reported as "not detected". That is, the air we breathe, the food we eat, and the water and other liquids we drink may have measurable concentrations of toxic chemicals, despite being reported as not detected and assumed to be absent. Furthermore, many chemicals, such as arsenic (As) in drinking water, are so toxic that they cannot be measured to safe levels and the allowable limits must be set at the lowest reportable concentrations. As a result, the allowable limits for some extremely toxic chemicals may be incorrectly set too high. Therefore, the consequences of this error pose a risk to public health and the environment. The sources of this error are explained and two improved ways of calculating method detection limit are presented.

PLOS ONE

Spectrophotometers are commonly used to measure the concentrations of a wide variety of analytes ... more Spectrophotometers are commonly used to measure the concentrations of a wide variety of analytes in drinking water and other matrixes; however, many laboratories with limited resources cannot afford to buy these very useful instruments. To meet this need, an accurate, precise, and affordable light emitting diode (LED) spectrophotometer was designed and built using best engineering practices and modern circuit design. The cost and performance of this LED spectrophotometer was compared against 4 common commercial spectrophotometers. More specifically, the performance of these spectrophotometers was evaluated from the upper limits of linear range, upper limits of operational range, calibration sensitivities, R 2 values, precisions of standards, estimated limits of detection, and percent calibration check standard recoveries for the determinations of iron (Fe), manganese (Mn), and fluoride (F −) in drinking water. This evaluation was done in the United States (U.S.

Applications in Plant Sciences

The Polypodium vulgare complex (Polypodiaceae) is a group of Northern Hemisphere fern species onc... more The Polypodium vulgare complex (Polypodiaceae) is a group of Northern Hemisphere fern species once recognized as a single species, P. vulgare L. During the 20th century, this single species was eventually split into 16 species and numerous sterile hybrids based on evidence from cytological, hybridization, geographical, and morphological studies (e.g., Haufler et al., 1995). Ten of these species have been described as diploids, and they form four lineages that are supported by multiple molecular markers and morphological evidence. Six more species are considered allopolyploids, derived from hybridization between two or more diploid progenitor species, likely within the last 15 million years (Bryan and Soltis, 1987; Haufler et al., 1995; Sigel et al., 2014). The patterns and mechanisms of evolution at the population level are not well understood, and no microsatellite markers have been previously developed for the P. vulgare complex, impeding progress toward understanding these recently derived species. One primarily North American lineage ('Clade A' in Sigel et al., 2014) is composed of three diploid species (P. appalachianum Haufler & Windham, P. amorphum Suksd., and P. sibiricum Sipliv.) and two allopolyploid species (P. saximontanum Windham and P. virginianum L.). The Appalachian rockcap fern, P. appalachianum, is distributed across the Appalachian Mountains, from Ontario to northern Georgia, and is a diploid (2n = 74; Haufler and Wang, 1991). The common rockcap fern, P. virginianum, is a tetraploid (2n = 148; Haufler et al., 1993) derived from hybridization between P. appalachianum and P. sibiricum. Polypodium virginianum overlaps the distribution of P. appalachianum in the Appalachian Mountains and is also found in the Ozark Mountains and the Great Lakes region (Haufler and Wang, 1991). Polypodium amorphum and P. saximontanum occur in the western United States, whereas P. sibiricum is distributed across northern Canada into Alaska and northern Asia. All species in this lineage tend to be found on rocky outcrops or cliffs, and P. appalachianum and P. virginianum are nearly morphologically indistinguishable where they co-occur (Haufler et al., 1993). Development of microsatellite markers focused on the diploid P. appalachianum will yield a novel genetic tool for use in evolutionary studies within the P. appalachianum-P. virginianum complex, within the broader Clade A complex, and possibly across the P. vulgare complex.

Cogent Food & Agriculture

Cabbage (Brassica oleracea) seeds were germinated and grown for 35 days in an organic standard su... more Cabbage (Brassica oleracea) seeds were germinated and grown for 35 days in an organic standard substrate contained in either plastic, peat, paper, or newspaper containers to determine whether the container material might affect growth. Days to emergence, days to first leaf, and developmental morphological traits and physiological characteristics were monitored. Differences in evaporation and pH of water in contact with the containers were measured in separate experiments. Evaporation was lowest from plastic and highest from peat containers, while pH was lowest with water in contact with peat containers. Plant growth was fastest and most robust in plastic containers as demonstrated by their shoot height, stem diameter, and root and shoot dry weights. Seedlings grown in newspaper containers presented exceedingly poor growth and showed signs of stress.

Calibration curves are commonly used for quantitative analysis in analytical chemistry to calcula... more Calibration curves are commonly used for quantitative analysis in analytical chemistry to calculate the concentrations of chemicals in samples. Typically, the concentration of the analyte, the chemical being quantified, is the independent variable and is plotted on the x-axis. The detector response, the reading from the instrument, is the dependent variable and is plotted on the y-axis. A calibration curve is made by plotting the known concentration of analyte versus the detector response. After a calibration curve is made, the unknown concentration of analyte in any sample is calculated from its detector response. Unfortunately, there is no standard procedure for objectively testing the fit of calibration curves in analytical chemistry. For example, the World Health Organization (WHO) and the United States Environmental Protection Agency (U.S. EPA) do not provide guidance for testing the linearity or curvature of calibration curves. Moreover, this important topic is not broached in...

The equation promulgated by 40 Code of Federal Regulations (CFR) to calculate method detection li... more The equation promulgated by 40 Code of Federal Regulations (CFR) to calculate method detection limit (MDL) and used since 1981 in the United States and other countries to protect public health and the environment is incorrect. As a result, toxic chemicals in a large number of air, food, water, wastes, and other environmental samples may in fact be present at measurable concentrations even though they are currently being reported as "not detected". That is, the air we breathe, the food we eat, and the water and other liquids we drink may have measurable concentrations of toxic chemicals, despite being reported as not detected and assumed to be absent. Furthermore, many chemicals, such as arsenic (As) in drinking water, are so toxic that they cannot be measured to safe levels and the allowable limits must be set at the lowest reportable concentrations. As a result, the allowable limits for some extremely toxic chemicals may be incorrectly set too high. Therefore, the consequences of this error pose a risk to public health and the environment. The sources of this error are explained and two improved ways of calculating method detection limit are presented.

Environmental Health, 2015

The World Health Organization (WHO) has established guidelines for drinking-water quality that co... more The World Health Organization (WHO) has established guidelines for drinking-water quality that cover biological and chemical hazards from both natural and anthropogenic sources. In the most recent edition of Guidelines for Drinking-water Quality (2011), the WHO withdrew, suspended, did not establish, or raised guidelines for the inorganic toxic substances manganese, molybdenum, nitrite, aluminum, boron, nickel, uranium, mercury, and selenium. In this paper, we review these changes to the WHO drinking-water guidelines, examining in detail the material presented in the WHO background documents for each of these toxic substances. In some cases, these WHO background documents use literature reviews that do not take into account scientific research published within the last 10 or more years. In addition, there are instances in which standard WHO practices for deriving guidelines are not used; for example, rounding and other mathematical errors are made. According to published meeting reports from the WHO Chemical Aspects Working Group, the WHO has a timetable for revising some of its guidelines for drinking-water quality, but for many of these toxic substances the planned changes are minimal or will be delayed for as long as 5 years. Given the limited nature of the planned WHO revisions to the inorganic toxic substances and the extended timetable for these revisions, we suggest that governments, researchers, and other stakeholders might establish independent recommendations for inorganic toxic substances and possibly other chemicals to proactively protect public health, or at the very least, revert to previous editions of the Guidelines for Drinking-water Quality, which were more protective of public health.

Environmental Health

The World Health Organization (WHO) has established guidelines for drinking-water quality that co... more The World Health Organization (WHO) has established guidelines for drinking-water quality that cover biological and chemical hazards from both natural and anthropogenic sources. In the most recent edition of Guidelines for Drinking-water Quality (2011), the WHO withdrew, suspended, did not establish, or raised guidelines for the inorganic toxic substances manganese, molybdenum, nitrite, aluminum, boron, nickel, uranium, mercury, and selenium. In this paper, we review these changes to the WHO drinking-water guidelines, examining in detail the material presented in the WHO background documents for each of these toxic substances. In some cases, these WHO background documents use literature reviews that do not take into account scientific research published within the last 10 or more years. In addition, there are instances in which standard WHO practices for deriving guidelines are not used; for example, rounding and other mathematical errors are made. According to published meeting reports from the WHO Chemical Aspects Working Group, the WHO has a timetable for revising some of its guidelines for drinking-water quality, but for many of these toxic substances the planned changes are minimal or will be delayed for as long as 5 years. Given the limited nature of the planned WHO revisions to the inorganic toxic substances and the extended timetable for these revisions, we suggest that governments, researchers, and other stakeholders might establish independent recommendations for inorganic toxic substances and possibly other chemicals to proactively protect public health, or at the very least, revert to previous editions of the Guidelines for Drinking-water Quality, which were more protective of public health.

The Science of the total environment, 2015

In South Asia, the technological and societal shift from drinking surface water to groundwater ha... more In South Asia, the technological and societal shift from drinking surface water to groundwater has resulted in a great reduction of acute diseases due to water borne pathogens. However, arsenic and other naturally occurring inorganic toxic substances present in groundwater in the region have been linked to a variety of chronic diseases, including cancers, heart disease, and neurological problems. Due to the highly specific symptoms of chronic arsenic poisoning, arsenic was the first inorganic toxic substance to be noticed at unsafe levels in the groundwater of West Bengal, India and Bangladesh. Subsequently, other inorganic toxic substances, including manganese, uranium, and fluoride have been found at unsafe levels in groundwater in South Asia. While numerous drinking water wells throughout Myanmar have been tested for arsenic, relatively little is known about the concentrations of other inorganic toxic substances in Myanmar groundwater. In this study, we analyzed samples from 18 d...