Heinz E. Braun

Investigations of pesticide contaminations in rural wells, 1979–1984, Ontario, Canada

Between the years 1979 and 1984, investigations were conducted into 311 events of suspected contaminations of wells with pesticides. This involved the analyses of water from 359 wells where the suspected contamination originated from (i) spills (ii) spray drift or (iii) surface runoff waters carrying pesticides into wells. Investigations covered 83 spill events involving 104 rural wells; tests revealed 79 of these became contaminated. The contaminations were caused by (i) spills of pesticide concentrates (ii) back-siphoning of spray solutions and/or (iii) spills from overfilling, emptying or rinsing spray equipment. The pesticides either entered directly into the wells or contaminated the area in the vicinity of the wells. In spite of cleanup attempts, difficulty was experienced in decontaminating most well waters and some had to be abandoned. The longest period of monitoring a contaminated well was 1, 117 days; during that time the decline in residue was slow.Investigations were made into 228 events involving 255 wells where spray drift and/or surface runoff waters with pesticides were observed as entering the well; however, only 55 were found to contain detectable residues. The highest proportion of these events was associated with surface runoff or spray drift from cornfields; of 86 wells involved only 26 contained measurable residues and all involved atrazine. Fifty-seven well investigations were associated with spraying right-of-ways and 16 waters were contaminated with 2,4-D and dichlorprop. The remaining 13 well contaminations were associated with various other land-use activities. It required 45 to 347 days to decontaminate these 55 wells.

Survey of farm wells for pesticides residues, Southern Ontario, Canada, 1981-1982, 1984

Water samples from 11 wells located in an area of intensive vegetable production on an organic soil were collected in 1981 and 1982, and analyzed for pesticide residues. Residues of diazinon, malathion, allidochlor, linuron, and prometryne were identified in four of the wells.Water samples from 91 wells were collected from farms on mineral soils across Southern Ontario during 1984 and analyzed for pesticide residues. Atrazine residues (0.1 to 74 μg/L) were present in 11 wells and trifluralin residues (41μg/L) contaminated one well. The highest residue of atrazine (74 μg/L) was present in one well along with contamination of three other herbicides and one insecticide. This was the result of a spill into the drilled well that gave residues of each component between 22 and 125μg/L. After 10 months of cleaning, this well was still contaminated.

Residues of organochlorine insecticides, industrial chemicals, and mercury in eggs and in tissues taken from healthy and emaciated common loons, Ontario, Canada, 1968-1980.

Between 1968 and 1980, 98 eggs were collected from active nests of the common loon (Gavia immer) in Ontario. Residues of ⌆DDT and PCB declined over this period while dieldrin and Hg appeared unchanged. Eggs collected in 1969 and 1970 had significantly thinner shells than eggs from a collection made before 1947. Between 1969 and 1979, 215 common loon carcasses were collected across Ontario, the result of having been drowned or shot or having died of diseases or unknown causes. Chemical analyses of 174 carcasses taken from healthy birds showed that adult loons accumulated higher levels of organochlorine and Hg residues than did juveniles. Tissues with high fat contents contained higher organochlorine levels while kidney, liver, and feathers had the highest Hg levels. Thirty loons were found to be emaciated with visibly lesser amounts of body fat and significantly lower levels of lipids in pectoral muscle tissue. Organochlorine but not Hg residues were one to two orders of magnitude higher in the wet tissues of emaciated birds than healthy birds. Higher residues of organochlorine chemicals were found in the uropygial gland, the oil secreted by this gland and belly and back feathers of emaciated birds when compared to healthy birds. It was concluded that losses of organochlorine chemical residues could occur through this gland. While Hg levels in feathers were elevated, Hg did not accumulate in the uropygial gland or in the secreted oil and was not the route for Hg content in feathers.In emaciated birds, mean brain levels of ⌆DDT (primarily DDE) were between 25 and 49 Μg/g, dieldrin 0.5 to 1.2 Μg/g, PCB 39 to 63 Μg/g, and mercury 1.0 to 1.8 Μg/g. The mean brain levels in healthy birds were between 0.2 and 0.9 Μg/g ⌆DDT, 0.01 and 0.05 Μg/g dieldrin, 0.6 and 2.0 Μg/g PCB, and 0.4 and 0.6 Μg/g mercury.

Residues of insecticides, and fungicides in fruit produced in Ontario, Canada, 1986-1988.

Between 1986 and 1988, 306 composite samples of fruit representing eight commodities were collected from farm deliveries to the marketplace in Ontario, Canada. All samples were analysed for insecticides and fungicides. The analysis procedure included tests for organochlorine, organophosphorus, synthetic pyrethroid and methylcarbamate insecticides and dithiocarbamate, dicarboximide and organochlorine fungicides. The commodities tested included apples, blueberries, cherries, grapes, peaches, pears, raspberries and strawberries. In 14% of all fruit samples, pesticide residues were below the detection limits, which ranged between 0.005 and 0.02 mg/kg. A further 14% had total combined pesticide residues below 0.1 mg/kg. Total combined fungicide and insecticide residues ranged from 0.1 to 11 mg/kg in 72% of samples. Six different pesticides were in violation of maximum residue limits (MRL) on 11 (3.6%) of fruit samples. Captan exceeded the 5 mg/kg MRL in five samples and EBDC exceeded the 7 mg/kg MRL in two. Other violations included single fruit samples with dicofol, endosulphan, phosalone and iprodione above the MRL. Raw grapes harvested for wine contained residues of 10 pesticides and the number changed little following the crushing of the grapes; however, fermentation into wine significantly reduced residues. Six insecticides and four fungicides were present on the raw grapes and 4/105 were above the MRL. Following crushing, four insecticides and five fungicides were identified and 4/40 were above the MRL. In wine only three insecticides were identified and all were well below the MRL. Carbaryl appeared to be the most persistent, declining very little between raw grapes and wine.

Organochlorine and organophosphorus residues in the fat of domestic farm animal species, Ontario, Canada 1986-1988.

During the period 1986-1988 a total of 602 samples of animal products were analysed for organochlorine and organophosphorus pesticides and industrial organic pollutants. Samples of abdominal fat were collected from avian, bovine, caprine, lupine, ovine and porcine species together with hen eggs. The following six compounds were identified in animal tissues: DDE, dieldrin, lindane, PCB, pentachlorophenol and tetrachlorophenol. Pentachlorophenol was the most frequently found contaminant, being identified in 35% of samples, and DDE was the second in 21%. All other contaminants were present in less than 10% of samples. The residues of all six compounds detected were added to give a combined residue. Forty-three per cent of samples had non-detectable residues. A further 31% had combined residues adding to less than 0.01 mg/kg. The highest combined residues ranged between 0.1 and 1.0 mg/kg and were present in 2.8% of samples. One egg sample had a residue of 0.16 mg/kg that exceeded the 0.1 mg/kg maximum residue limit for pentachlorophenol. Residues of chlordane and its metabolites, heptachlor and its epoxide, endosulphan and its sulphate metabolite, dicofol, HCB and mirex were below their detection limits in all samples and no residues of the organophosphorus insecticide listed as applied to livestock were found in meat, fat or egg tissues.

Removal of captan from treated apples

Apples were dipped in a captan solution and allowed to equilibrate for 60 to 120 hr. Apples were then washed, diced, peeled, and cooked in several combinations to determine how the initial residues were removed. Rinsing, thorough washing, wiping, and combinations of these procedures reduced residues of captan by 43 to 94%. Boiling the whole apple or cooking the peeled and diced apple removed and destroyed 70 to 98% of the residue. The combination of thorough washing and cooking gave almost 100% removal. Peeling the unwashed apple transferred 30% of the captan residue to the pulp. The half-life of captan in water at pH 8.5 was found to be less than one hr at 22°C and 13 hr at 5°C; at pH 5.5 the half-life was 13 hr at 22°C and 208 hr at 5°C.

Monitoring Ontario‐grown apples for pest control chemicals used in their production, 1978–86

Between 1978 and 1986, 305 samples of apples were monitored for the residues of a wide range of pesticides used in their production. Three (1%) contained residues above the maximum residue limits (MRL) permitted under the Canadian Food and Drug Act and regulations; two involved phosalone at 5.9 and 6.2 mg/kg respectively and one involved diphenylamine at 6.7 mg/kg when the MRL was 5.0 mg/kg for both compounds. Low residues of dicofol, endosulfan, phosalone, phosmet, captan, daminozide and diphenylamine were frequently found; however they were well below the MRLs. These residue levels were correlated with survey data on the areas of the apple crop treated with specific pesticides. Residues of carbaryl, diazinon, ethion, azinophosmethyl, parathion, and dithiocarbamate fungicides were found occasionally; all were well below the MRLs and correlated with the pattern of use. No residues of PCB were found to a limit of detection of 0.01 mg/kg.

PCB and DDE Residues in Milk Supplies of Ontario, Canada 1985-1986

Concerns on the presence of PCBs in milk have arisen because of spills of these industrial chemicals on roads, around storage sites, and because of their presence in waste oils used to treat gravel roads with up to 25 ppm being allowed up to 1970 and 5 ppm up to 1984. The possibility of the spread of PCB into water supplies of rural areas of the province has been a constant concern and the presence of PCB in bovine milk serves as a reliable indicator of the degree of contamination. Milk supplies in Southern Ontario have been monitored for PCB and DDE since 1970-71. In 1985-86 the monitoring program was extended to include all regions of the province where milk is produced in order to further assess the incidence, levels, and trends of PCB in the provincial milk supply.

Residues of insecticides, fungicides and herbicides in fruit produced in Ontario, Canada, 1980-1984

Resultats de dosages systematiques realises sur des peches, cerises et fraises, en relation avec la reglementation sur les taux de residus de pesticides

Efficiency of water rinsing for the decontamination of used pesticide containers

The efficiency of water rinsings for the decontamination of emptied pesticide containers was investigated in the period 1979–1981; nineteen formulations representing seven insecticides and two fungicides were studied. Following normal emptying procedures, the amount of retained pesticides ranged from a low of 0.06% to a high of 7.48%. By successively rinsing with volumes of water equal to one-tenth of the volume of the containers, as many as five rinses were required to remove 99% of the retained formulation. When containers were held in an inverted position and allowed to drain one minute prior to rinsing, three successive rinsings were sufficient for most formulations to remove 99% of the retained pesticide. Decontamination by rinsing was achieved most readily with water-soluble concentrates and wettable powders while flowable suspensions appeared to be the most difficult to remove.