Magnetic flux density associated with power lines was measured in three communities within the Ci... more Magnetic flux density associated with power lines was measured in three communities within the City of Kingston (population 123,000), Ontario, Canada during a two-week period in August 2003. Spot measurements were taken during the day (0900-1700 h) and in the evening (1700-2100 h) Monday to Friday at intersections, along the sidewalk, and at the front door of buildings on both sides of the street. The mean magnetic flux density for downtown commercial, downtown residential, and suburban residential was 28, 3.2, and 4.0 mG respectively. Of the almost 4000 measurements taken in this study, 76% were above 2 mG, the lower limit associated with childhood leukemia in epidemiological studies. More specifically, the downtown commercial, downtown residential, and suburban communities had 97%, 68% and 42% of readings above 2 mG respectively. As many as 64% of the measurements in the commercial district were above 12 mG, which has been associated with enhanced growth of human breast cancer cells in vitro and 54% were above 16 mG, which has been associated with increased risk of miscarriages. Day and evening measurements within each community were similar with some exceptions. Magnetic flux densities at intersections were similar or slightly higher than values measured along residential streets and were significantly higher than street values in the Kingston's commercial district. Exposure to street level magnetic fields may be considerable in some communities posing a potential risk to delivery personnel, street vendors, utility employees, maintenance workers, police, and others who spent time in this environment. These outdoor environments are important sources of electromagnetic field exposure for certain types of occupations but they may also contribute signficiantly to non-occupational exposure and should be included when calculating exposure estimates.
Biological Effects of EMFs, 3rd International Workshop, 2004
Abstract
Magnetic flux density associated with power lines was measured in three communities wit... more Abstract
Magnetic flux density associated with power lines was measured in three communities within the City of Kingston (population 123,000), Ontario, Canada during a two-week period in August 2003. Spot measurements were taken during the day (0900–1700 h) and in the evening (1700–2100 h) Monday to Friday at intersections, along the sidewalk, and at the front door of buildings on both sides of the street. The mean magnetic flux density for downtown commercial, downtown residential, and suburban residential was 28, 3.2, and 4.0 mG respectively. Of the almost 4000 measurements taken in this study, 76% were above 2 mG, the lower limit associated with childhood leukemia in epidemiological studies. More specifically, the downtown commercial, downtown residential, and suburban communities had 97%, 68% and 42% of readings above 2 mG respectively. As many as 64% of the measurements in the commercial district were above 12 mG, which has been associated with enhanced growth of human breast cancer cells in vitro and 54% were above 16 mG, which has been associated with increased risk of miscarriages. Day and evening measurements within each community were similar with some exceptions. Magnetic flux densities at intersections were similar or slightly higher than values measured along residential streets and were significantly higher than street values in the Kingston’s commercial district. Exposure to street level magnetic fields may be considerable in some communities posing a potential risk to delivery personnel, street vendors, utility employees, maintenance workers, police, and others who spent time in this environment. These outdoor environments are important sources of electromagnetic field exposure for certain types of occupations but they may also contribute signficiantly to non-occupational exposure and should be included when calculating exposure estimates.
The effect of aluminum on the survival of Daphnia catawba, Holopedium gibberum, Chaoborus punctip... more The effect of aluminum on the survival of Daphnia catawba, Holopedium gibberum, Chaoborus punctipennis, and Chironomus anthrocinus was determined. Experiments were conducted in soft water adjusted to pH 6.5 (original), 5.0, 4.5, 4.0, and 3.5, at three concentrations of aluminum (0.02, 0.32, 1.02 mg/L) which cover the range typical of soft-water lakes exposed to acidic precipitation in eastern North America. Our results indicate that D. catawba was the most acid sensitive of the four species tested. It died rapidly below pH 5.0, whereas the others could survive at pHs as low as 4.0 (H. gibberum) and 3.5 (C. punctipennis and C. anthrocinus). None of the invertebrates were particularly sensitive to aluminum. Mortality, attributable to aluminum, occurred only at pH 6.5 for D. catawba at the highest aluminum concentration tested (1.02 mg/L). Most of the aluminum in this treatment was present as a solid-phase aluminum hydroxide complex. Based on our results, these species should be able to tolerate aluminum concentrations in excess of those which now occur in recently acidified oligotrophic lakes. If they are eliminated from acidic environments it is likely to be due to competition for food and (or) prédation pressure rather than direct aluminum toxicity.
Ground current commonly referred to as "stray voltage" has been... more Ground current commonly referred to as "stray voltage" has been an issue on dairy farms since electricity was first brought to rural America. Equipment that generates high-frequency voltage transients on electrical wires combined with a multigrounded (electrical distribution) system and inadequate neutral returns all contribute to ground current. Despite decades of problems, we are no closer to resolving this issue, in part, due to three misconceptions that are addressed in this study. Misconception 1. The current standard of 1 V at cow contact is adequate to protect dairy cows; Misconception 2. Frequencies higher than 60 Hz do not need to be considered; and Misconception 3. All sources of ground current originate on the farm that has a ground current problem. This case study of a Wisconsin dairy farm documents, 1. how to establish permanent monitoring of ground current (step potential) on a dairy farm; 2. how to determine and remediate both on-farm and off-farm sources contributing to step potential; 3. which step-potential metrics relate to cow comfort and milk production; and 4. how these metrics relate to established standards. On-farm sources include lighting, variable speed frequency drives on motors, radio frequency identification system and off-farm sources are due to a poor primary neutral return on the utility side of the distribution system. A step-potential threshold of 1 V root mean square (RMS) at 60 Hz is inadequate to protect dairy cows as decreases of a few mV peak-peak at higher frequencies increases milk production, reduces milking time and improves cow comfort.
Magnetic flux density associated with power lines was measured in three communities within the Ci... more Magnetic flux density associated with power lines was measured in three communities within the City of Kingston (population 123,000), Ontario, Canada during a two-week period in August 2003. Spot measurements were taken during the day (0900-1700 h) and in the evening (1700-2100 h) Monday to Friday at intersections, along the sidewalk, and at the front door of buildings on both sides of the street. The mean magnetic flux density for downtown commercial, downtown residential, and suburban residential was 28, 3.2, and 4.0 mG respectively. Of the almost 4000 measurements taken in this study, 76% were above 2 mG, the lower limit associated with childhood leukemia in epidemiological studies. More specifically, the downtown commercial, downtown residential, and suburban communities had 97%, 68% and 42% of readings above 2 mG respectively. As many as 64% of the measurements in the commercial district were above 12 mG, which has been associated with enhanced growth of human breast cancer cells in vitro and 54% were above 16 mG, which has been associated with increased risk of miscarriages. Day and evening measurements within each community were similar with some exceptions. Magnetic flux densities at intersections were similar or slightly higher than values measured along residential streets and were significantly higher than street values in the Kingston's commercial district. Exposure to street level magnetic fields may be considerable in some communities posing a potential risk to delivery personnel, street vendors, utility employees, maintenance workers, police, and others who spent time in this environment. These outdoor environments are important sources of electromagnetic field exposure for certain types of occupations but they may also contribute signficiantly to non-occupational exposure and should be included when calculating exposure estimates.
Biological Effects of EMFs, 3rd International Workshop, 2004
Abstract
Magnetic flux density associated with power lines was measured in three communities wit... more Abstract
Magnetic flux density associated with power lines was measured in three communities within the City of Kingston (population 123,000), Ontario, Canada during a two-week period in August 2003. Spot measurements were taken during the day (0900–1700 h) and in the evening (1700–2100 h) Monday to Friday at intersections, along the sidewalk, and at the front door of buildings on both sides of the street. The mean magnetic flux density for downtown commercial, downtown residential, and suburban residential was 28, 3.2, and 4.0 mG respectively. Of the almost 4000 measurements taken in this study, 76% were above 2 mG, the lower limit associated with childhood leukemia in epidemiological studies. More specifically, the downtown commercial, downtown residential, and suburban communities had 97%, 68% and 42% of readings above 2 mG respectively. As many as 64% of the measurements in the commercial district were above 12 mG, which has been associated with enhanced growth of human breast cancer cells in vitro and 54% were above 16 mG, which has been associated with increased risk of miscarriages. Day and evening measurements within each community were similar with some exceptions. Magnetic flux densities at intersections were similar or slightly higher than values measured along residential streets and were significantly higher than street values in the Kingston’s commercial district. Exposure to street level magnetic fields may be considerable in some communities posing a potential risk to delivery personnel, street vendors, utility employees, maintenance workers, police, and others who spent time in this environment. These outdoor environments are important sources of electromagnetic field exposure for certain types of occupations but they may also contribute signficiantly to non-occupational exposure and should be included when calculating exposure estimates.
The effect of aluminum on the survival of Daphnia catawba, Holopedium gibberum, Chaoborus punctip... more The effect of aluminum on the survival of Daphnia catawba, Holopedium gibberum, Chaoborus punctipennis, and Chironomus anthrocinus was determined. Experiments were conducted in soft water adjusted to pH 6.5 (original), 5.0, 4.5, 4.0, and 3.5, at three concentrations of aluminum (0.02, 0.32, 1.02 mg/L) which cover the range typical of soft-water lakes exposed to acidic precipitation in eastern North America. Our results indicate that D. catawba was the most acid sensitive of the four species tested. It died rapidly below pH 5.0, whereas the others could survive at pHs as low as 4.0 (H. gibberum) and 3.5 (C. punctipennis and C. anthrocinus). None of the invertebrates were particularly sensitive to aluminum. Mortality, attributable to aluminum, occurred only at pH 6.5 for D. catawba at the highest aluminum concentration tested (1.02 mg/L). Most of the aluminum in this treatment was present as a solid-phase aluminum hydroxide complex. Based on our results, these species should be able to tolerate aluminum concentrations in excess of those which now occur in recently acidified oligotrophic lakes. If they are eliminated from acidic environments it is likely to be due to competition for food and (or) prédation pressure rather than direct aluminum toxicity.
Ground current commonly referred to as "stray voltage" has been... more Ground current commonly referred to as "stray voltage" has been an issue on dairy farms since electricity was first brought to rural America. Equipment that generates high-frequency voltage transients on electrical wires combined with a multigrounded (electrical distribution) system and inadequate neutral returns all contribute to ground current. Despite decades of problems, we are no closer to resolving this issue, in part, due to three misconceptions that are addressed in this study. Misconception 1. The current standard of 1 V at cow contact is adequate to protect dairy cows; Misconception 2. Frequencies higher than 60 Hz do not need to be considered; and Misconception 3. All sources of ground current originate on the farm that has a ground current problem. This case study of a Wisconsin dairy farm documents, 1. how to establish permanent monitoring of ground current (step potential) on a dairy farm; 2. how to determine and remediate both on-farm and off-farm sources contributing to step potential; 3. which step-potential metrics relate to cow comfort and milk production; and 4. how these metrics relate to established standards. On-farm sources include lighting, variable speed frequency drives on motors, radio frequency identification system and off-farm sources are due to a poor primary neutral return on the utility side of the distribution system. A step-potential threshold of 1 V root mean square (RMS) at 60 Hz is inadequate to protect dairy cows as decreases of a few mV peak-peak at higher frequencies increases milk production, reduces milking time and improves cow comfort.
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Papers by Magda Havas
Magnetic flux density associated with power lines was measured in three communities within the City of Kingston (population 123,000), Ontario, Canada during a two-week period in August 2003. Spot measurements were taken during the day (0900–1700 h) and in the evening (1700–2100 h) Monday to Friday at intersections, along the sidewalk, and at the front door of buildings on both sides of the street. The mean magnetic flux density for downtown commercial, downtown residential, and suburban residential was 28, 3.2, and 4.0 mG respectively. Of the almost 4000 measurements taken in this study, 76% were above 2 mG, the lower limit associated with childhood leukemia in epidemiological studies. More specifically, the downtown commercial, downtown residential, and suburban communities had 97%, 68% and 42% of readings above 2 mG respectively. As many as 64% of the measurements in the commercial district were above 12 mG, which has been associated with enhanced growth of human breast cancer cells in vitro and 54% were above 16 mG, which has been associated with increased risk of miscarriages. Day and evening measurements within each community were similar with some exceptions. Magnetic flux densities at intersections were similar or slightly higher than values measured along residential streets and were significantly higher than street values in the Kingston’s commercial district. Exposure to street level magnetic fields may be considerable in some communities posing a potential risk to delivery personnel, street vendors, utility employees, maintenance workers, police, and others who spent time in this environment. These outdoor environments are important sources of electromagnetic field exposure for certain types of occupations but they may also contribute signficiantly to non-occupational exposure and should be included when calculating exposure estimates.
Magnetic flux density associated with power lines was measured in three communities within the City of Kingston (population 123,000), Ontario, Canada during a two-week period in August 2003. Spot measurements were taken during the day (0900–1700 h) and in the evening (1700–2100 h) Monday to Friday at intersections, along the sidewalk, and at the front door of buildings on both sides of the street. The mean magnetic flux density for downtown commercial, downtown residential, and suburban residential was 28, 3.2, and 4.0 mG respectively. Of the almost 4000 measurements taken in this study, 76% were above 2 mG, the lower limit associated with childhood leukemia in epidemiological studies. More specifically, the downtown commercial, downtown residential, and suburban communities had 97%, 68% and 42% of readings above 2 mG respectively. As many as 64% of the measurements in the commercial district were above 12 mG, which has been associated with enhanced growth of human breast cancer cells in vitro and 54% were above 16 mG, which has been associated with increased risk of miscarriages. Day and evening measurements within each community were similar with some exceptions. Magnetic flux densities at intersections were similar or slightly higher than values measured along residential streets and were significantly higher than street values in the Kingston’s commercial district. Exposure to street level magnetic fields may be considerable in some communities posing a potential risk to delivery personnel, street vendors, utility employees, maintenance workers, police, and others who spent time in this environment. These outdoor environments are important sources of electromagnetic field exposure for certain types of occupations but they may also contribute signficiantly to non-occupational exposure and should be included when calculating exposure estimates.