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Biological effects of a 765‐kV transmission line: Exposures and thresholds in honeybee colonies
Author(s) -
Greenberg Bernard,
Bindokas Vytautas P.,
Gauger James R.
Publication year - 1981
Publication title -
bioelectromagnetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.435
H-Index - 81
eISSN - 1521-186X
pISSN - 0197-8462
DOI - 10.1002/bem.2250020404
Subject(s) - biology , transmission (telecommunications) , zoology , telecommunications , engineering
Honeybee colonies exposed under a 765‐kV, 60‐Hz transmission line at 7 kV/m show the following sequence of effects: 1) increased motor activity with transient increase in hive temperature; 2) abnormal propolization; 3) impaired hive weight gain; 4) queen loss and abnormal production of queen cells; 5) decreased sealed brood; and 6) poor winter survival. When colonies were exposed at 5 different E fields (7, 5.5, 4.1, 1.8, and 0.65–0.85 kV/m) at incremental distances from the line, different thresholds for biologic effects were obtained. Hive net weights showed significant dose‐related lags at the following exposures: 7 kV/m, one week; 5.5 kV/m, 2 weeks; and 4.1 kV/m, 11 weeks. The two lowest exposure groups had normal weight after 25 weeks. Abnormal propolization of hive entrances did not occur below 4.1 kV/m. Queen loss occurred in 6 of 7 colonies at 7 kV/m and 1 of 7 at 5.5 kV/m, but not below. Foraging rates were significantly lower only at 7 and 5.5 kV/m. Hive weight impairment and abnormal propolization occur at lower E‐field intensity than other effects and limit the “biological effects corridor” of the transmission line to approximately 23 m beyond a ground line projection of each outer phase wire. Intrahive E fields of 15–100 kV/m were measured with a displacement current sensor. Step‐potential‐induced currents up to 0.5 μA were measured in an electrically equivalent bee model placed on the honeycomb in a hive exposed at 7 kV/m. At 1.8 kV/m body currents were a few nanoamperes, or two orders of magnitude lower, and these colonies showed no effects. E‐field versus electric shock mechanisms are discussed.