Hans Løkke

Ecoepidemiology—A casuistic discipline describing ecological disturbances and damages in relation to their specific causes: Exemplified by chlorinated phenols and chlorophenoxy acids☆

Ecoepidemiology is a new concept created in analogy to human epidemiology, and aims at the study of ecotoxicological effects at the levels of ecosystems, biological communities, and populations in relation to causative environmental exposures, mostly by chemicals. By way of example, ecoepidemiology is described by presenting an example of unintentional dissipation and possible discharges of chlorophenols and phenoxy acids into the terrestrial environment and--as a more specific case--a marine, aquatic area, viz., the Køge Bay immediately to the south of Copenhagen, Denmark. The examples are illustrative of the complex situation which characterizes most ecoepidemiological cases. Difficulties with which the ecoepidemiologist are confronted are not only the identification of possible causative and confounding chemicals, and the description of ecoepidemiological effects per se, but also the assessment of critical pathways of multimedium pollutants. Biomonitoring, computer-based handling of data from natural localities, and determination of a variety of anthropogenic impact factors are necessary elements of ecoepidemiological studies.

Accumulation of chlorinated hydrocarbons in moss from artificial rainwater

Simulation experiments on the sorption, uptake, accumulation and evaporation of hexachlorobenzene (HCB), y-hexachlorocyclohexane (y-HCH) and a-hexachlorocyclohexane (a-HCH) were carried out with the moss species Pleurozium schreberi. The experimental findings were computed in mathematical models and validated by comparison with the findings others have obtained in field studies using chlorinated hydrocarbons in naturally growing moss for air pollution monitoring. From the present experiments it could be concluded that organic hydrocarbons are accumulated in moss by a dynamic equilibrium between moss and environment due to the sorption-evaporation balance. The actual contents in the moss are a reflection of the exposure of the moss during a period of about one month only. The use of concentrations of chlorinated hydrocarbons in moss as an indication of the air pollution level in general is a difficult technique and its application demands great caution.

Leaching of ethylene glycol and ethanol in subsoils

The use of the heat pumps connected to ground coils wins widespread interest in the heating of buildings, but in cases of leakage it may involve a risk of ground water pollution caused by anti-freeze mixture components. The adsorption of individual components, such as ethylene glycol, ethanol, methanol, and benzoic acid onto different soil types was studied at 6 °C by use of a batch procedure. No adsorption (or only slight) was observed for any of the test compounds onto samples of subhorizons of sandy till, clayey till, and melt water sand.Leaching experiments with undisturbed soil cores of sandy till showed that 14C-labelled ethylene glycol or ethanol closely followed the movement of water when cloride was used as a tracer. The percolation experiments were conducted during 79 to 154 day periods at 10 °C and under anaerobic conditions. Darcy velocities varied between 1 and 3 mm day−1. About 100% of the added amounts of 14C were recovered in the effluents, although only 74 to 77% of ethylene glycol and 84 to 89% of ethanol were determined as the parent compounds by gas chromatography. Experiments on leaching of ethanol under controlled oxygen supply showed that degradation took place dependent on oxygen availability.

Phytotoxicological effects of Di-(2-ethyl hexyl)-phthalate and Di-n-butyl-phthalate on higher plants in laboratory and field experiments

Abstract Climate chamber experiments on the deposition, uptake and phytotoxic effects of di-(2-ethyl hexyl)-phthalate (DEHP) and di-(n-butyl)-phthalate (DBP) were carried out by foliar application on Sinapis alba, Brassica napus and Achillea millefolium. The laboratory experiments were transposed to the field and compared with similar field studies on Sinapis and Brassica. Experimental results were validated in relation to findings obtained on naturally growing Achillea and snow samples around a known phthalate emission source. DEHP caused no visible effects on the plants under the experimental conditions used in the present laboratory and field studies. DBP caused chlorosis on the leaves of both Sinapis and Brassica in laboratory experiments whereas Achillea was not affected. In field experiments the phytotoxic effects of DBP were reduced and chlorotic spots could be observed on Brassica only. On the basis of the DEHP and DBP contents in snow samples it appeared probable that the concentrations of the two compounds found in the air might not cause any injury to the growth of higher plants, either around an emission source in an industrial area or elsewhere.

Studies of mobility of di-iso-butyl phthalate (DiBP), di-N-butyl phthalate (DBP), and di-(2-ethyl hexyl) phthalate (DEHP) by plant foliage treatment in a closed terrestrial simulation chamber

Abstract A climate chamber was constructed for model studies of mobility and effects of chemical substances within simplified terrestrial systems. The chamber functions and its performance were tested by foliar applications of phthalates on higher plants. A low elimination rate from foliage was observed for DEHP. More than 95% of DiBP and DBP were eliminated within 15 days. 1.5 μg cm −2 of DBP caused chlorosis on the leaves of Sinapis alba L.

PCDDs, PCDFs, and metals in selected danish soils

Topsoil samples from five locations in Denmark were collected and analyzed for polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and selected heavy metals. The upper soil layers contained elevated concentrations of PCDDs, PCDFs, Pb, Zn, and Cu compared to the lower layers. The soil contents of PCDDs plus PCDFs were closely related to Pb contents. Higher concentrations were found near urban areas relative to strictly rural locations. From the presented data the provisional Danish background content of PCDDs plus PCDFs is estimated to be 4-7 micrograms m-2 in the topsoil of coniferous forests.

Picein and piceol concentrations in Norway spruce

The concentrations of the glucoside picein and its aglucone piceol (4-hydroxy acetophenone) in the needles of Norway spruce (Picea abies (L.) Karsten) are considered indicators of plant stress. By use of two clones and a natural population of Norway spruce it was shown that the picein concentration was dependent on the site and the provenance of the trees. No effects were observed by normal treatment with the herbicides atrazine, glyphosate, and hexazinone, or by drought. The significance of different environmental factors is discussed.

Degradation of 4-nitrophenol in two Danish soils

The degradation of 4-nitrophenol was studied at 10°C and at an initial concentration of 2 mgkg−1 in a topsoil and a subsoil under aerobic and anaerobic conditions. In topsoil the half-life (t12) was 0·7 to 1·2 days under aerobic and 14 days under anaerobic conditions, respectively. Under anaerobic conditions, addition of glucose (50 mgkg−1) reduced t12 to 6 days. After addition of nitrate-N (50 mgkg−1) t12 was 10 days. By combined addition of glucose and nitrate t12 was 11 days. In the subsoil t12 was 40 days under aerobic conditions and abiotic degradation seems to be of some importance. Under anaerobic conditions the degradation in the subsoil was slow.

Uptake of 2,4-D in higher plants from artificial rain

Sinapis alba L., Lapsana communis L., Achillea millefolium L., Brassica napus L., Lactuca sativa L., and Lycopersicum esculentum L. were exposed to 2,4-dichlorophenoxy [2-14C]acetic acid (2,4-D) at 10 micrograms liter-1 in artificial rain, pH 6.5 and 3.3. The 2,4-D was absorbed in all species tested. Concentrations of parent 2,4-D appeared at the highest level in Achillea (0.1 mg kg-1 dry wt), and at zero level in Lycopersicum. Twenty-one daily treatments at pH 6.5 for 30-min periods increased dry-matter concentrations (P less than or equal to 0.05) in the leaves of Achillea and decreased those in Brassica. No change in dry-matter concentration was observed in the leaves of Brassica by seven daily treatments for 30-min periods at pH 3.3.

Effects of 2,4-dichlorophenoxyacetic acid in artificial acid rain on Brassica napus and Sinapis alba

The effect of 2,4-dichlorophenoxyacetic (2,4-D) acid in artificial rain at pH 3.3 was examined for young plants of rape (Brassica napus L.) and white mustard (Sinapis alba L.). Plants were treated in a closed simulation chamber system with varying CO2 supply (198-418 ppm). Single or daily showers were applied for 20-30 min at varying 2,4-D concentrations (0, 0.03, 0.1, 0.5, and 2.5 mg liter-1). The plants were sampled 5 days after the last treatment. Epinasty was observed for Brassica at 0.5 mg liter-1 and for Sinapis at 0.1 mg liter-1 2,4-D. Leaf to stem dry weight ratios increased with increasing CO2 concentrations in the air and decreased following single treatments with 0.5 or 2.5 mg liter-1 2,4-D in the rain. Dose-effect relationships are proposed for both plant species. Leaf dry matter weights per area unit decreased with increasing CO2 concentrations, but were not significantly affected by the 2,4-D treatments.