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A method is described for the determination of residues of the herbicide diclofop-methyl and its metabolite, diclofop, in soil and crops. The residues were extracted with acetone-light petroleum and extracts were concentrated (diclofop was derivatized to its pentafluorobenzyl derivative), and then the products were purified on a chromatographic column containing alumina, silver-alumina and Florisil. Finally, they were determined by gas chromatography using an electron-capture detector. The detection limits of diclofop-methyl and diclofop were between 0.01 and 0.05 mg/kg. The average recoveries were 76.4-97.2% and 72.8-105.2%, respectively, making the method suitable for statutory residue testing purposes.

A gas chromatographic/mass spectrometric (GC/MS) screening method has been developed for the determination of pesticide residues in a variety of crop samples. Samples are extracted with acetonitrile and partitioned with sodium chloride saturated aqueous solution. Targeted pesticide analytes are separated on a short, narrow bore capillary column, identified by electron ionization MS scanned from 100 to 400 amu, and quantitated by the monitoring of base ions and internal standards. The accuracy of the quantitative determination measured in terms of average percentage recovery of 143 compounds in 13 crop samples was 92% with a relative standard deviation of 22%.

For the incidence of non-volatile nitrosamines in the staple foods and vegetables, corn, millet, turnip and turnip chips collected from Linxian County Henan Province, a high incidence area of esophageal cancer, were collected, analyzed and compared with the foods from Huairou County Beijing, a low risk area. Nitrososarcosine (NSAR), nitrosoproline (NPRO) and two unknown non-volatile compounds were found in the food samples from Linxian, and the levels of NSAR in corn ranged 0.7-1.1 ppb and in turnip chips ranged 20.5-962.5 ppb. NSAR level detected in corn samples from Huairou County was not significantly different from that of Linxian. The possibility that the high content of nitrosamines in turnip chips is due to microbial infections is discussed.

Malate, which plays many essential roles in plant metabolism, is a potent in vitro inhibitor of the cytosolic enzyme phosphoenolpyruvate carboxylase (PEPC). Because PEPC activity leads to malate biosynthesis, malate is assumed to attenuate its own synthesis in situ. To test this hypothesis, we measured directly the malate content of picoliter samples of Raphanus root-hair cytoplasm using quantitative histochemical techniques. We also obtained an estimate for malate accumulation in these cells. These values were compared with the PEPC activity of individual root hairs (less than 2 ng). The results indicate that high cytoplasmic malate concentration does not severely inhibit PEPC in situ. We suggest that the focus for studies on the regulation of organic anion accumulation be on the interactive effects of malate and other PEPC effectors.

Significantly higher nitrate content was detected in drinking water and vegetables grown by the rural population in the regions where industrial enterprises producing chemical fertilizers are located, as compared to the control regions. It has been concluded that a special attention should be paid to the daily level of nitrates ingested by the population (especially by children) in the industrial regions of the Republic and to their health state.

The ethylenebisdithiocarbamate (EBDC) fungicide, nabam, was determined in several crop matrixes using liquid chromatography with postcolumn reaction detection. After separation by micellar liquid chromatography, nabam (EBDC sodium salt) was acid hydrolyzed to ethylenediamine and fluorigenically labeled with o-phthalaldehyde-mercaptoethanol (OPA-MERC). Standard curves were linear from the detection limit of ca 1 ng to 1000 ng. Nabam was recovered in high yield (89 plus or minus 7.7%) over a range of concentrations (0.1 to 20 ppm) from fortified samples of papaya, lettuce, cucumber, spinach, and applesauce using a simple extraction method. Efforts to convert the more popular EBDC fungicides, maneb and mancozeb, to nabam are discussed.

A selective method for the determination of altertoxin-I and altertoxin-II by high-performance liquid chromatography with electrochemical detection is described. Altertoxins were separated on a reversed-phase column with methanol-water containing 0.1 M sodium nitrate and 1 mM nitric acid (60:40) as eluent and detected with dual in-series electrodes operating in the "redox" mode (generator electrode +1.0 V, indicator electrode -0.1 V). The method was applied successfully to the determination of sub-ppm levels of altertoxins in samples of maize, rice and tomatoes infected by Alternaria alternata.

This paper describes a set of multipathway, multimedia models for estimating potential human exposure to environmental contaminants. The models link concentrations of an environmental contaminant in air, water, and soil to human exposure through inhalation, ingestion, and dermal-contact routes. The relationship between concentration of a contaminant in an environmental medium and human exposure is determined with pathway exposure factors (PEFs). A PEF is an algebraic expression that incorporates information on human physiology and lifestyle together with models of environmental partitioning and translates a concentration (i.e., mg/m3 in air, mg/liter in water, or mg/kg in soil) into a lifetime-equivalent chronic daily intake (CDI) in mg/kg-day. Human, animal, and environmental data used in calculating PEFs are presented and discussed. Generalized PEFs are derived for air----inhalation, air----ingestion, water----inhalation, water----ingestion, water----dermal uptake, soil----inhalation, soil----ingestion, and soil----dermal uptake pathways. To illustrate the application of the PEF expressions, we apply them to soil-based contamination of multiple environmental media by arsenic, tetrachloroethylene (PCE), and trinitrotoluene (TNT).

It has become apparent that removing dairy products from the diets of patients with galactosaemia does not sufficiently diminish the deleterious signs. We have determined the amount of soluble monomeric galactose in 45 fruits and vegetables using capillary gas chromatography and selective ion monitoring. Galactose contents ranged from less than 0.1 mg per 100 g of tissue in artichoke, mushroom, olive, and peanut to 35.4 mg per 100 g in persimmon. Fruits and vegetables with over 10 mg per 100 g included date, papaya, bell pepper, tomato and watermelon. These results will provide important data for planning the diets of patients with galactosaemia.

Raw carrot juice contains a considerable amount of alpha- and beta-carotene, which makes carrot an excellent source of vitamin A. Heat treatment of the juice at temperatures comparable to those at pasteurization and boiling does not change the carotenes, while heating at temperatures used during sterilization results in rearrangement of the carotene molecules and a decrease in total carotenes. The all-trans alpha- and beta-carotenes appear partly as cis-isomers, especially the 13-cis-isomer. Isomerization of the carotenes leads to a decrease in their vitamin A activity. Carotenes also seem to be anticarcinogens but the extent to which this property is influenced by isomerization is still unknown.

A duplicate diet study has been carried out on a group of Harwell employees in order to investigate the food types in which radiocaesium from Chernobyl was most likely to be found, and also the intake of radiocaesium in food with relation to observed whole-body levels. The duplicate diet study indicated that the highest levels of radiocaesium were in milk and meat or fruit and vegetables. Radiocaesium concentrations in food of all types are small compared to the most restrictive generalized derived limit. Daily intakes of radiocaesium measured by the diet study, of the order of 2-3 Bq day-1, generally agreed with values calculated from whole-body measurements. Committed does from radiocaesium have been estimated from dietary intakes to be in the range 3-29 muSv year-1, while whole-body measurements indicate a range of 6-18 muSv year-1; these doses are small compared to other sources of internal irradiation and to recommended limits.

The seeds of lesser-known species - Cucumeropsis mannii, Lagenaria sicceraria varieties 1 and 2 and Telfairia occidentalis, of Cucurbitaceae family were studied. The protein content of C. mannii was 36.1% and the varieties 1 and 2 of L. sicceraria had 32.1% and 33.3% respectively. Telfairia occidentalis had protein content of 33.2%. The fat contents of C. mannii, L. Sicceraria var. 1 and 2 and T. occidentalis were 44.4%, 44.6%, 46.9% and 42.3% respectively. The crude fibre content for each of the two varieties of L. sicceraria was 3.6% and T. occidentalis had 5.5%. Cucumeropsis mannii had the lowest (2.4%) fibre content. The carbohydrate contents for L. Sicceraria var. 2, C. mannii, and T. occidentalis were 12.6%, 13.2% and 14.4% respectively. Lagenaria sicceraria var. 1 had the highest value of carbohydrate (15.8%). The species were relatively rich in potassium and magnesium with range of values of 0.56% to 0.68% and 434 ppm to 444 ppm respectively. Cucumeropsis mannii and Lagenaria sicceraria var. 2 had relatively high contents of calcium (117 ppm) and iron (109 ppm) respectively. The kernels of these species exhibited lipase activity. Telfairia occidentalis showed the highest degree of lipase activity.

We have quantitatively analyzed human plasma for the following carotenoids: all-trans-lutein, all-trans-zeaxanthin, alpha-cryptoxanthin, beta-cryptoxanthin, the sum of all-trans-lycopene and its cis isomers, alpha-carotene and beta-carotene. In addition, we have tentatively identified and quantified 13-cis-lutein and 13-cis-zeaxanthin in human plasma. The latter two cis isomers are also apparent in samples of two common food items, spinach and corn meal. We have analyzed the ratios of all of the members of the beta, beta family of carotenoids (zeaxanthin, beta-cryptoxanthin and beta-carotene) to their corresponding beta, epsilon structural isomers (lutein, alpha-cryptoxanthin and alpha-carotene) in human plasma. There are marked differences in these ratios, with beta-carotene and beta-cryptoxanthin predominating in the carotene and monohydroxy-xanthophyll classes and lutein predominating in the dihydroxy-xanthophyll class. These differences could be attributable to dietary intake or to specific mechanisms in the way humans absorb and utilize these compounds.

A 65-year-old woman developed a severe, generalized phototoxic reaction following a visit to a suntan parlor. History taking revealed that she had consumed a large quantity of celery root (Apium graveolens) 1 hour earlier. With the use of thin-layer chromatography, methoxsalen (8-methoxypsoralen) and 5-methoxypsoralen were identified in the extract from a similar celery root. The biologic activity of this extract, as evaluated with the semiquantitative Candida albicans inhibition technique, indicated a total psoralen dose of approximately 45 mg. Substantial amounts of psoralen may be absorbed from vegetables, such as celery, and under unusual circumstances, this may constitute a health hazard.

Ascorbate oxidase was immobilised on cyanogen bromide activated-Sepharose 4B and incorporated in a flow-injection system with amperometric detection at a glassy carbon electrode at +0.6 V. On passage through the immobilised ascorbate oxidase a fraction of the L-ascorbic acid was converted into dehydroascorbic acid and the decrease in signal was measured. This could be directly related to the amount of L-ascorbic acid present. The calibration graph was linear over the range 0-400 ng ml(-1) with a correlation coefficient of 0.9994. The detection limit (2 sigma) in phosphate buffer (0.08 M, pH 5.5) was 4.0 ng ml(-1). The relative standard deviation for a 200 ng ml(-1) standard was 1.0% (n = 10) and the sampling throughput was 30 samples h(-1). The method was used for the simple and rapid determination of L-ascorbic acid in fruit and vegetable juice.

A new taste-modifying protein named curculin was extracted with 0.5 M NaCl from the fruits of Curculigo latifolia and purified by ammonium sulfate fractionation, CM-Sepharose ion-exchange chromatography, and gel filtration. Purified curculin thus obtained gave a single band having a Mr of 12,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the presence of 8 M urea. The molecular weight determined by low-angle laser light scattering was 27,800. These results suggest that native curculin is a dimer of a 12,000-Da polypeptide. The complete amino acid sequence of curculin was determined by automatic Edman degradation. Curculin consists of 114 residues. Curculin itself elicits a sweet taste. After curculin, water elicits a sweet taste, and sour substances induce a stronger sense of sweetness. No protein with both sweet-tasting and taste-modifying activities has ever been found. There are five sets of tripeptides common to miraculin (a taste-modifying protein), six sets of tripeptides common to thaumatin (a sweet protein), and two sets of tripeptides common to monellin (a sweet protein). Anti-miraculin serum was not immunologically reactive with curculin. The mechanism of the taste-modifying action of curculin is discussed.

Radiation and hygienic appraisal of vegetables cultivated under various kinds of irrigation is presented. Critical radionuclides are determined along with major vegetable products owing to which the great amount of radionuclides is absorbed. Contribution of vegetables and potato cultivated under irrigation into the total body intake of radionuclides by local residents has been evaluated.

PIXE (Proton inducted X-ray emission) analysis of food samples was carried out with 2 Mev protons. The measured seven trace elements for 62 food samples are listed in tables.

A total of 244 samples of cereals (wheat flour, rice, and maize), pulses (arhar, moong, gram, lentil, and black gram), spices (turmeric, chili, coriander, and black pepper), vegetables (potato, onion, spinach, cabbage, brinjal, and tomato), fruits (mango, guava, apple, and grape), milk, butter, Deshi ghee, and edible oils (vegetable, mustard, groundnut, and sesame) collected from different cities of Northern Province (Utter Pradesh) were analyzed by gas liquid chromatography for the presence of organochlorine pesticide residues. Residues of hexachlorocyclohexane (HCH) and 2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane (DDT) were detected in about 85% of the total samples of cereals, spices, milk, butter, Deshi ghee, and edible oils analyzed in the present study. However, the residue levels were either very small (less than 0.06 ppm) or not detected at all in pulses, vegetables, and fruits as compared with very high concentrations in wheat flour (4.42 and 0.12 ppm), butter (1.19 and 4.85 ppm), mustard oil (1.26 and 2.42 ppm), Deshi ghee (1.10 and 3.84 ppm), vegetable oil (1.02 and 0.59 ppm), groundnut oil (0.51 and 1.49 ppm), and chili (0.48 and 1.92 ppm). The levels of HCH and DDT residues detected in rice, maize, turmeric, corlander, black pepper, and all the vegetables and fruits were also lower than those found in wheat flour, oil, and fat samples analyzed in the present study. These findings suggest that a restricted and controlled use of such persistent pesticides may be useful for decreasing their contamination levels in different food items.

Studies of the lead and cadmium content of soils and vegetables from 126 allotments in 12 towns in a polluted region of Poland are described. Metal concentrations in parsley, celery, carrots and red beet were determined using AAS. In most cases, metal concentrations in soils and vegetables exceeded accepted standards and concentrations found in rural regions. A total of 756 vegetable samples were studied and only 170 met the standard for lead and 17 for cadmium. The lowest lead content was found in parsley roots and the highest in celery leaves. Cadmium content between species did not differ greatly and the highest concentrations were recorded for celery. The metal intake by the consumer was also calculated using questionnaire data concerning vegetable consumption. In relation to the reference area, the metal intake in the polluted area was 2-5 times higher for lead and 2-16 times higher for cadmium. The main species responsible for the high metal concentrations were carrots and red beet. Replacing carrots and red beet with the same species grown in an unpolluted region would reduce the consumer's metal intake from vegetables considerably.

We extended the study of oxalate bioavailability by testing 7 additional food items: brewed tea, tea with milk, turnip greens, okra, peanuts and almonds. Nine normal subjects ingested a large serving of each of these items. The bioavailable oxalate was calculated from the increment in urinary oxalate during 8 hours after ingestion and bioavailability was determined as the percentage of total oxalate content in a given food item represented by bioavailable oxalate. Brewed tea and tea with milk, with a high oxalate content, had a low bioavailable oxalate level (1.17 and 0.44 mg. per load) because of the low oxalate availability (bioavailability of 0.08 and 0.03%). Turnip greens, with a satisfactory oxalate bioavailability (5.8%), had a negligible effect on urinary oxalate excretion, since oxalate content was relatively low (12 mg. per load). Okra, with a moderate oxalate content (264 mg. per load) had a negligible bioavailable oxalate (0.28 mg. per load). Only peanuts and almonds provided a moderate increase in oxalate excretion (3 to 5 mg. per load) due to the modest oxalate content (116 and 131 mg. per load) and oxalate bioavailability (3.8 and 2.8%). Thus, the ability of various oxalate-rich foods to augment urinary oxalate excretion depends not only on oxalate content but on the bioavailability.

True protein digestibilities of 17 protein sources were estimated by 6 laboratories using an in vitro, 3-enzyme digestion system in a pH stat. Samples from animal, vegetable, and mixed food sources were freeze-dried (if not already dried), ground, mixed, and shipped to each collaborator along with a sodium caseinate standard and trypsin, chymotrypsin, and peptidase. The uptake of titrant during enzymatic digestion was used to calculate estimates of digestibility. Digestibilities ranged from 100% for casein to 89.9% for whole wheat cereal. Mean relative standard deviations for repeatability were 1.4% for rolled oats and less than 1% for the remaining 16 samples. Mean relative standard deviations for reproducibility ranged from 5.0 to 0.8%; values were less than 2.5% for 13 of the 17 samples.

Proteins in solution need not exist in a single rigid structure but can exist in a dynamic equilibrium among structural forms. The problems that this poses for structure determination using nuclear Overhauser effect data from two-dimensional NMR experiments are discussed and illustrated with data on functionally equivalent proteins from two different species. One of these proteins, acyl carrier protein from Escherichia coli, shows a single set of resonances, easily interpreted on the basis of a single rigid structure. However, the related protein, acyl carrier protein from spinach, shows two sets of resonances, suggesting that two conformers in dynamic equilibrium would be a better structural model.

Between 1986 and 1988, 433 composite vegetable samples representing 16 commodities were collected from farm deliveries to the marketplace in Ontario, Canada. All samples were analysed for insecticides and fungicides. The analyses included organochlorine, organophosphorus, synthetic pyrethroid, and N-methylcarbamate insecticides and dithiocarbamate, dicarboximide, and organochlorine fungicides. The commodities tested included asparagus, beans, carrots, celery, cole crops, cucumbers, lettuce, onions, peppers, potatoes, radishes, rutabagas and tomatoes. In 64% of samples, no pesticide residues were identified to the limits of detection which ranged from 0.005 to 0.05 mg/kg. A further 22% had combined insecticide and fungicide residues below 0.1 mg/kg. Most of the positive findings were a fraction of the Maximum Residue Limit permitted for each commodity under the Canadian Food and Drugs Act and Regulation. Three samples (0.7%) had residues that exceeded the MRL. These involved diazinon and parathion on celery and chlorothalonil on peppers. While some commodities had no detectable residues others had measurable residues of up to three separate pesticides. The most were found on celery, lettuce and field tomatoes.

The lead and cadmium content of 20 species of edible vegetable collected in Tarragona Province (Spain) was investigated. Samples consisting of bulbs, and leaves and soft stalks (chard, parsley, spinach and lettuce) contained the highest levels of both metals. In contrast, fruits and similar garden produce (tomato, green pepper, cucumber, artichoke, green bean and broad bean) contained the lowest concentrations of lead and cadmium in both the northern and southern area of the province. Most species analyzed did not show any significant differences between the two study areas. The mean daily intakes of lead and cadmium by man have been estimated to be: 47.5 micrograms Pb and 15.3 micrograms Cd (north), and 37.5 micrograms Pb and 32.5 micrograms Cd (south). These values do not pose a health risk for consumers, according to the levels proposed by FAO/WHO.

Cadmium and lead were determined in fresh asparagus, as a function of diameter and portions, by atomic absorption spectrophotometry to evaluate the contribution of these vegetables to the daily intake of cadmium and lead in Spain. Cadmium content of the asparagus ranged from less than 0.006 mg/kg to 0.062 mg/kg, whereas lead content varied from 0.059 to 0.409 mg/kg. The concentration of cadmium and lead was compared statistically for the different diameters and portions of asparagus. The asparagus tip/remainder ratio metal concentration was determined and a greater concentration of cadmium and lead in the tip relative to the remainder of the asparagus was observed. If we take into account the mean level of cadmium and lead (0.022 mg/kg and 0.165 mg/kg respectively), the daily intake contribution of these metals in Spain is 0.04 micrograms/day for cadmium and 0.3 microgram/day for lead.

Several oxidant media were evaluated for the generation of lead hydride from slurry samples and their application to the determination of lead in vegetables and fish by hydride generation atomic absorption spectrometry. Three oxidant - acid media were compared: hydrogen peroxide - nitric acid, ammonium persulphate - nitric acid and potassium dichromate - lactic acid. The powdered samples were suspended in Triton X-100 and shaken with 10.0 g of blown zirconia spheres until a slurry was formed. The potassium dichromate - lactic acid medium was the most satisfactory for the determination of lead in fish and vegetables, providing the lowest detection limits as a result of its high sensitivity and low blank values. The ammonium persulphate - nitric acid medium gave good accuracy, precision and selectivity for vegetables (1-2 p.p.m. of lead); however, with fish (0.1-1 p.p.m. of lead) it was only a semi-quantitative medium for the determination of lead owing to its lack of sensitivity and selectivity. The hydrogen peroxide - nitric acid medium was unsatisfactory for the generation of lead hydride from slurry samples because of decomposition of hydrogen peroxide by the organic matter in the sample.

Three outbreaks of food poisoning involving watermelons or cucumbers and caused by the carbamate pesticide aldicarb occurred in California between 1985 and 1988. For each outbreak, and for an outbreak of aldicarb poisoning associated with English cucumbers previously reported in the literature, dosages of aldicarb sulfoxide that caused the illnesses were estimated. Estimated dosages ranged between 0.0023 [corrected] and 0.06 mg/kg body weight, and most were well below the 0.025 mg/kg Lowest Observed Effect Level (LOEL) for subclinical blood cholinesterase depression previously reported for humans. These findings are consistent with aldicarb sulfoxide (ASO) illnesses that have occurred in other states. Aldicarb appears to be more toxic than previously suspected. Scientific and regulatory implications are discussed.

A reproducible and sensitive gas chromatographic method has been developed for the trace analysis of fluazifop-butyl, haloxyfop-ethoxyethyl and quizalofop-ethyl as well as their main metabolites (corresponding acids analysed after conversion to methyl esters) in some fruits and vegetables treated with herbicidal sprays. Comparable detection limits (0.01 mg/kg) were achieved when mass fragmentography and/or the electron capture detector were employed. However, in the latter case, bromination of fluazifop esters had to be carried out prior to GC analysis. By means of the nitrogen-phosphorus detector, determination of residues at a level of 0.05 mg/kg was possible. The residue values found in strawberries, cabbages, cauliflower and carrots were used to discuss the degree of metabolic hydrolysis of parent esters, i.e. active ingredients of herbicides.

Glucarate is normally present in tissues and body fluids and is in equilibrium with D-glucaro-1,4-lactone, a natural inhibitor of beta-glucuronidase activity. Dietary calcium glucarate, a sustained-release from of glucarate, elevates the blood level of D-glucaro-1,4-lactone which suppresses blood and tissue beta-glucuronidase activity. A single dose of CaG (4.5 mmole/kg body weight) inhibited beta-glucuronidase activity in serum and liver, lung, and intestinal microsomes by 57, 44, 37, and 39%, respectively. A chronic administration of calcium glucarate (4% in diet) also decreased beta-glucuronidase activity in intestinal and liver microsomes. Maximal inhibition of beta-glucuronidase activity in serum was observed from 12 noon to 2:00 PM. In contrast, maximum inhibition of beta-glucuronidase activity in intestinal and liver microsomes occurred during mornings, although a secondary depression in intestinal microsomes also occurred around 4 PM. A 4% calcium glucarate supplemented diet also inhibited beta-glucuronidase activity by 70% and 54%, of the bacterial flora obtained from proximal (small intestine) and distal (colon) segments of intestine, respectively. Due to the potential effect of dietary glucarate on net glucuronidation and on other metabolic pathways, glucaric acid levels in various foods were determined. The glucaric acid content varied from a low of 1.12-1.73 mg/100 g for broccoli and potatoes to a high of 4.53 mg/100 g for oranges.

Concentrations of radionuclides originating from the Chernobyl reactor accident were measured as a function of time in air, rainwater, grass, cow's milk, vegetables and dust by means of high-resolution gamma-ray spectroscopy. Special attention was paid to grass and milk originating from the same meadows. Also, milk of cows temporarily kept inside after the accident was monitored until a few days after their release from the stables. Activity ratios in various types of samples and the implication of the sheltering measures for cows are discussed.

Linear furanocoumarin contents and antibiotic resistance to Liriomyza trifolii (Burgess) were documented for Apium species being investigated in a celery breeding program. In no-choice tests, L. trifolii fed more, produced more offspring, and had the highest pupal and adult productivity on the widely planted cultivar 'Tall Utah' 52-70R (Apium graveolens L.). Antibiotic effects of the commercial cultivar 'Tall Utah' 52-70 HK and University of California families 87A-147 and 87A-338, derived from A. chilense Hook and Arn., were intermediate. Only A. nodiflorum (L.) Lag (accession 87A-236) did not allow survival beyond the larval stage. Concentrations of the carcinogenic and mutagenic linear furanocoumarins varied by location within plants (leaves usually greater than petioles), by specific compound (trend: psoralen less than xanthotoxin less than bergapten or isopimpinellin), and between accessions. A. nodiflorum had the lowest foliar levels of phototoxic furanocoumarins (11.8 micrograms/g fresh weight) and the best potential for use in the breeding program. Foliar levels of phototoxic furanocoumarins (psoralen, bergapten, and xanthotoxin) in plants 87A-147-3 (406 micrograms/g), 87A-147-2 (292.9 micrograms/g), and the family 87A-338 (265.9 micrograms/g) were 22.6, 16.3, and 14.8 times higher, respectively, than the concentration known to produce contact dermatitis (18 micrograms/g). Even with such variability in concentration, the foliar content of linear furanocoumarins (individually or total) and L. trifolii adult production were not correlated.

The Watford and South Mimms sections of the London Orbital (M25) Motorway opened in late 1986. The rate of lead contamination in vegetation, surface soil, dust and airborne fractions since those dates is presented. Lead values were determined by inductively coupled plasma-source mass spectrometry (ICP-MS) with inter-analytical method comparison using flameless atomic absorption spectroscopy (NFAAS). A consistently high level of correlation (r = +0.91) was obtained for analysis of digested reference materials and (r = +0.84) for digested environmental sample solutions using these two methods. Quality control assessment was made using seven international reference materials covering the range of matrices under investigation. Analytical precision values (n = 20 replicates) for ICP-MS measured Pb levels in soil and vegetative reference materials are 6.1 to 11.1% and 3.3 to 7.1%, respectively. Overall accuracy of the analytical procedures used in this study is very good with a high degree of agreement between measured ICP-MS values and those either certified or reported in the literature. A rapid rate of Pb deposition occurs within the first months following the opening of the motorway in relation to emissions from approximately 90,000 vehicles day-1 (Watford) and approximately 75,000 vehicles day-1 (South Mimms). At 12 months elevated Pb levels extend to distances of greater than 100 m from the motorway.(ABSTRACT TRUNCATED AT 250 WORDS)

A rehydratable dry-film plating procedure for aerobic plate counts has been compared to the standard agar plate method (966.23B and C, 15th ed.; 46.014-46.015, 14th ed.) in a collaborative study by 12 laboratories. Each laboratory analyzed the normal microflora of 3 samples in duplicate for 6 products. The aerobic plate counts ranged from 1.0 x 10(3) to 1.0 x 10(8) cfu/g. The products were flour, nuts, frozen raw shrimp, spice, frozen raw ground turkey, and frozen and refrigerated vegetables. Repeatability standard deviations of the 2 methods did not differ significantly for 13 of 18 test samples. For 1 shrimp and 2 turkey samples, the dry-film method had lower repeatability variances (P less than 0.05) and for 1 spice sample the agar method had lower repeatability variances (P less than 0.05). Relative standard deviations of repeatability were between 1.7 and 15.5% for the dry-film method and 1.2 and 16.0% for the agar method. Relative standard deviations of reproducibility ranged from 2.4 to 23.4% for the dry-film method and 2.3 to 18.8% for the agar method. The dry rehydratable film method has been adopted official first action for determination of the aerobic plate count.

A liquid chromatographic (LC) method for determination of total sulfite in foods and beverages by alkali extraction followed by ion exclusion chromatographic separation and electrochemical detection (IEC-EC) was collaboratively studied by 9 laboratories. Blind duplicate samples of starch, diluted lemon juice, wine cooler, dehydrated seafood, and instant mashed potatoes were analyzed without spiking and with added sulfite at 2 levels. The initial sulfite levels varied from 0 to 384 ppm SO2, and the levels added varied from 10 to 400 ppm. The initial sulfite levels determined by the IEC-EC method and the Monier-Williams method were in good agreement. Recovery of added sulfite by the IEC-EC method was generally higher than that by the Monier-Williams method. Within-laboratory repeatability (RSDr) for the IEC-EC method varied from 4.4 to 26.0%, and overall reproducibility (RSDR) varied from 8.5 to 39.3%. The collaborators found the method to be fast, sensitive, and easy to use, which makes it a useful alternative to the Monier-Williams method. The method has been adopted official first action.

We examined the carotenoid content of selected foods consistently found to be associated with a lower risk for various epithelial cancers in epidemiologic studies. Both raw and cooked samples of green, leafy vegetables and yellow or orange vegetables were quantitatively examined by high-performance liquid chromatography for individual carotenoid content. The results indicated that fresh, green, leafy vegetables were moderately high in beta carotene (0.5-14.6 mg/100 g) and very high in oxygenated carotenoids or xanthophylls, primarily lutein and its stereoisomers (2.3-63.0 mg/100g) [corrected]. The fresh, yellow or orange vegetables examined were very high in beta carotene (16.0-120.5 mg/100 g) [corrected] but had no detectable nonhydrocarbon carotenoids. Cooking differentially reduced the lutein content compared with the beta carotene content in green, leafy vegetables. These analyses suggest that consumption of carotenoids in addition to beta carotene may be associated with a lower risk for cancer.

A simple and rapid wet-digestion procedure is described for the determination of total mercury in botanical samples by cold vapour atomic absorption spectrometry. The method is based on the oxidising properties of potassium dichromate in dilute sulphuric acid and was tested on two National Institute of Standards and Technology Standard Reference Materials. The mass of the samples taken for analysis was about 0.5 g in all instances, corresponding to an amount of mercury of the order of 0.075-0.040 micrograms depending on the material. The results were compared with those obtained using the Association of Official Analytical Chemists official digestion technique, which involves the use of nitric and sulphuric acids, and a second technique based on the action of nitric and perchloric acids. The proposed method provided better accuracy and showed good precision. Its ability to achieve the decomposition of two organomercurials for full mercury recovery was verified.

The accumulation of cadmium by four crops (cabbage, carrot, lettuce and radish) grown on soils contaminated from a variety of sources was investigated in greenhouse pot experiments. Stepwise multiple regression analyses of the data revealed that, out of the 23 soil variables determined, only eight were significantly related to cadmium accumulation in the edible plant tissues. The most frequently occurring soil parameter was total cadmium, which was inversely related to plant cadmium accumulation (CdPlant tissue/CdSoil). This implies that, for the heterogeneous group of soils used, as the concentration of cadmium in the soil increases the proportion available to the plant decreases. This may be due to the presence of metallic ore particles and/or the high sorptive capacity of the most contaminated soils. When the data were divided into two groups: sewage sludge amended soils and inorganically contaminated soils, the R-squared values were usually enhanced and some differences occurred in the variables included in the multiple regression equations; this may be indicative of the differences in speciation. Cadmium accumulation by plants grown on sewage sludge amended soils was lower than that for the inorganically contaminated soils. The heterogeneity of the inorganically contaminated group of soils resulted in lower R-squared values for the multiple regression equations; this group of soils exhibited a wide range of soil variables, such as pH, and had been contaminated by a variety of means, such as atmospheric deposition from metal smelters and the dumping of mine wastes.

Three liquid chromatographic (LC) methods employing amperometric detection were compared with the collaboratively studied FDA optimized Monier-Williams distillation method for the determination of total sulfite in 5 food types. The foods included lemon juice, white wine, instant mashed potatoes, golden raisins, and onion flakes. Two of the LC methods (one employing headspace sampling and the other direct injection) used ion-exchange chromatography with a basic mobile phase (pH about 10.8) and a glassy carbon electrode; the third (employing direct injection) used ion-exclusion chromatography with an acidic mobile phase (pH about 2) and a platinum electrode. All 4 methods produced similar results for the wine, lemon juice, and raisins. Results were different for instant mashed potatoes and onion flakes. The headspace-LC method and direct ion-exclusion LC method, both of which employed an alkaline sample extraction, yielded significantly higher values for sulfite in instant potatoes than did the other 2 methods. A large interfering peak with both direct LC methods prevented quantitation of sulfite in the onion flakes. All methods can detect sulfite as low as about 1 microgram/g in 4 of 5 food types examined.

The content of lead, cadmium and mercury was determined in various sorts of Polish vegetables grown on soil or in hothouses in the years 1986-1988 using for the determination of Pb and Cd the extraction flame ASA method after dry mineralization at about 400 degrees C and for Hg the flameless ASA method after wet mineralization. In 1988 soil investigations were conducted parallelly in the areas where these vegetables had been grown. Vegetable samples were taken directly from the producers in 18 provinces, from areas not contaminated with these metals by industrial plants and traffic. About 2.5 thousand vegetable samples and about 650 soil samples were investigated. A considerable part of the vegetables, especially those whose roots are consumed, contained excessive amounts of lead--over 0.3 mg/kg (e.g. over 20% of samples of parsley leaves) and cadmium--over 0.3 mg/kg (nearly 40% of carrots samples, and about 30% of beets, lettuce grown on soil or in hothouses, and parsley roots, about 20% of samples of parsley leaves grown on soil). The levels of mercury were usually of the order of thousandths mg/kg. The mean values of these metals in soil were frequently much higher than the values regarded as most frequent in the soils of not contaminated regions of Poland.

The conditions were evolved and checked for simultaneous determination of cadmium and lead levels in plant material using the flame technique of ASA. For decomposition of the organic substances in plant material wet mineralization was used with a mixture of nitric acid, perchloric acid and sulpuric acid in volume proportions 6:2:0.25. The levels of cadmium and lead were determined in the organic phase after extraction with n-butyl acetate of the previously produced complexes with NaDDTK. The obtained limits of cadmium and lead detectability were 0.002 and 0.02 mg/kg respectively. The recovery rate of the method ranged from 96 to 98%, while the variability index was from 2.6 to 10.2%. The correctness of the evolved analytical procedure was confirmed by determination of the content of both elements in the NBS-SRM 1571 standard (orchard leaves) and by participation in the international interlaboratory investigation of the Polish standard (dried cabbage leaves).

Maximal permissible amounts of nitrates in vegetables and potatoes in Poland are proposed. These food products were divided into four groups according to their ability of accumulation of these substances. Moreover, a group of vegetables from special raising plots was isolated, they would be used for feeding small children, patients, and elderly subjects which would have a declared higher health quality.

The contents of cadmium, lead mercury, copper, manganese and zinc in 242 samples of 37 different species of domestic and imported fruits have been determined. Also contents of the same heavy metals, except mercury, have been determined in 205 samples of 7 species of domestic vegetables (lettuce, spinach, endive, beetroots, onions, celeriac and Swedish turnips). The median contents (in mg/kg fresh mass of the edible part) found for fruits are: Cd 0.002; Pb 0.017; Hg 0.002; Cu 0.61; Mn 0.52 and Zn 0.99. In the vegetables median levels have been found (mg/kg) of 0.009-0.073 for Cd, 0.01-0.03 for Pb, less than 0.2-0.3 for Cu, 0.69-1.41 for Mn and 0.95-5.5 for Zn. The contribution of fruits to the tolerable daily intakes of Cd, Pb and Hg is, for an average consumption pattern, less than 1%. On the other hand, the contribution to the recommended amounts of the essential elements Cu, Mn, and Zn is no more than 1%-3%. From the vegetables an average portion of spinach contains 19% and 2.6% of the tolerable daily amounts of Cd and Pb, respectively. For the other species of vegetables these figures are less than 5% for Cd (except for endive, 6.8%) and for lead less than 1%. Spinach contributes considerably to the need for Cu, Mn and Zn, in general more than 10% of the recommended daily amounts. The other species of vegetables contribute only from less than 1% to less than few percents.

Total dietary fiber (TDF) values for cereal grains, fruits, vegetables, processed foods, and purified or semi-purified dietary fiber products were determined by a new method using 8M urea and enzymes (urea enzymatic dialysis, UED, method). The results are compared with the official AOAC procedure. Soluble and insoluble dietary fiber were determined for several of these foodstuffs and compared with the NDF values. Crude protein and ash contamination was usually lower with the UED method compared with the AOAC method, particularly for samples that formed gels during ethanol precipitation. Urea and the heat stable amylase were effective in removing starch even at relatively low temperatures of the assay (50 degrees C). The new assay is relatively economical in use of equipment, enzymes, and reagents. Studies are currently in progress to minimize the assay time for the UED method while further improving its flexibility and robustness. The results of the studies will be discussed.