Element and radionuclide concentrations in food: FDA Total Diet Study 1991-1996.

Food purchased throughout the United States during 1991-1997 under the U.S. Food and Drug Administration's Total Diet Study (TDS) program were analyzed for elements and radionuclides. The program is described with emphasis on food analysis and quality control, including independent interlaboratory exercises. Analytical results are summarized for Cd, Pb, Ni, As, Hg, Se, Cu, Zn, Mn, Fe, Mg, Ca, P, K, and Na and for 137Cs, 131I, 106Ru, and 90Sr. Concentration data are provided to expand the information base used to support assessments of the safety and nutritive value of the U.S. food supply and for their potential use in food composition databases. For selected foods, comparisons were made with past TDS results and with those reported in the literature. An extensive listing of the analytical data is available on the FDA CFSAN Website.

Determination of sodium in biological materials by instrumental neutron activation analysis.

A formalized method for determining sodium in biological materials by instrumental neutron activation analysis is presented. The method includes common procedures from the numerous options available to this historically nonformalized analytical technique. The number of procedural options is restricted to minimize the method's complexity, yet the method is still applicable to a variety of neutron activation facilities. High accuracy and precision are achieved by placing bounds on allowed uncertainty at critical stages of the analysis. Analytical results from the U.S. Food and Drug Administration laboratory and 4 other laboratories demonstrate the method's performance.

US Food and Drug Administration survey of cadmium, lead and other elements in clams and oysters.

In Fiscal Years 1985/1986, the US Food and Drug Administration conducted a survey of cadmium, lead and other elements in fresh clams and oysters collected from US coastal areas in use for shellfish production. Shellfish were analysed for cadmium and lead by using a dry ash-anodic stripping voltammetric method. Other elements (aluminium, arsenic, beryllium, calcium, chromium, cobalt, copper, iron, magnesium, manganese, molybdenum, nickel, phosphorus, potassium, selenium, sodium, strontium, vanadium and zinc) were determined by using inductively coupled plasma-atomic emission spectrometry, direct current plasma-atomic emission spectrometry or hydride generation atomic absorption spectrometry. A total of 75 hardshell clam, 59 softshell clam, 104 Eastern oyster and 40 Pacific oyster samples were analysed for cadmium and lead. Average levels found were 0.09, 0.05, 0.51 and 1.1 mg/kg wet weight for cadmium and 0.24, 0.30, 0.11 and 0.06 mg/kg wet weight for lead in hardshell clams, softshell clams, Eastern oysters and Pacific oysters, respectively. The other 19 elements were determined in 10-104 samples of the four types of shellfish. These data provide baseline values for elements in clams and oysters harvested from US coastal waters.

History of the Food and Drug Administration's Total Diet Study (Part II), 1987-1993.

The Total Diet Studies conducted by the U.S. Food and Drug Administration (FDA) provide yearly information on levels of pesticide residues, contaminants, and nutrients in the food supply and diets of specific age-sex groups. They also identify trends and changes in the levels of these substances in the food supply and in diets over time. Results are useful in making policy decisions regarding the safety of the food supply, food additives, pesticide use, nutrient fortification, and food labeling. This paper provides information on studies performed by FDA from 1987 to 1993.

Sensitivity of the quick color test for indicating lead release from ceramicware.

A quick color test (QCT) for indicating the presence of leachable Pb on ceramicware was evaluated as a screening tool. Fourteen sets of cups and mugs (197 pieces) of undecorated glazed ceramicware were tested. The QCT indicated the presence of leachable Pb on 95% of the cups and mugs at or above approximately 2 micrograms/mL. The QCT is an inexpensive and rapid qualitative test for Pb that can be conducted with a portable kit.

Survey of lead and cadmium in adult canned foods eaten by young children.

A U.S. Food and Drug Administration survey of lead and cadmium in 10 adult canned foods commonly eaten by children less than 5 years old was conducted between October 1981 and September 1985. The survey, which included foods preserved by a commercial canning process and packaged in metal containers, found the highest mean levels of lead (0.32 micrograms/g) in tuna and of cadmium (0.02 micrograms/g) in tuna and tomatoes. Lead levels in foods packaged in lead-soldered cans were about 5 times as high as those in foods packaged in nonlead-soldered cans. Mean lead levels appeared to decline over the 4 years of the study. Cadmium levels were usually below the data reporting limit (0.01 micrograms/g).

Influence of automatic dishwashings and scrubbings on release of lead from glazed ceramicware.

Use of lead glazes on ceramicware and the release of lead from finished glazes are reviewed. Single units of ceramicware with initial lead leach levels from less than 0.1 to 470 micrograms/mL were subjected to multiple automatic dishwashings with intermediate scrubbing of the ware by plastic fiber pads. Ware was periodically leached with 4% acetic acid solution at room temperature for 24 h, and the solutions were analyzed for lead. Release of lead under these conditions is discussed. Results indicated that neither passive leachings nor multiple dishwashings and scrubbings can predict future lead-release characteristics of glazes and decorations.

Determination of copper, iron, and nickel in oils and fats by direct graphite furnace atomic absorption spectrometry: summary of collaborative study.

A collaborative study of a method for the determination of copper, iron, and nickel in edible oils and fats by direct graphite furnace atomic absorption spectrometry was recently conducted by the International Union of Pure and Applied Chemistry. The quantitation limits of the method are 5 micrograms/kg for copper and 10 micrograms/kg for iron and nickel. The method has been adopted official first action as an IUPAC-AOAC method.

Thimble glass frit nebulizer for atomic spectrometry.

A thimble-shaped glass frit nebulizer has been developed for atomic spectrometry. The thimble glass frit was pressurized internally by gases such as helium (He) or argon (Ar) while the test solution was applied externally to the frit. The pressurized gas exited through the pores of the glass frit and shattered the thin liquid film flowing on the surface of the thimble-shaped device to form small droplets. A small spray chamber surrounded the nebulizer to remove the large droplets. Small droplets were then introduced into inductively coupled plasmas (ICP) sustained in either Ar or He. To reduce the memory effect noted in the frit-type nebulizers, a clean-out system was also devised. Detection limits, signal-to-background ratios (S/B), precision, memory effects, noise power spectra (NPS), and particle size distributions measured with the new nebulizer were compared to those of disk and cylindrical glass frit nebulizers and the commonly used pneumatic nebulizer for Ar ICP atomic emission spectrometry (AES). Analytical performance was also measured for He ICP by using frit-type nebulizers and an ultrasonic nebulizer.

Survey of lead in canned evaporated milk.

A Food and Drug Administration survey of lead in canned evaporated milk conducted in fiscal year 1985/86 found a mean level of 0.006 micrograms Pb/g. This level is much lower than that found in previous surveys and is attributed to the use of nonlead-soldered cans for packaging evaporated milk.

Evaluation of electron capture gas chromatographic method for determination of methyl mercury in freezer-case seafoods.

A method was recently adopted by AOAC for determination of methyl-bound mercury in canned and fresh-frozen seafood by electron capture gas chromatography. That method was applied to the analysis of commercially prepared freezer-case seafoods. None of the commercially added ingredients produced electron capture responses that interfered in the analysis for methyl mercury. Recoveries of 95.7-114% were obtained in fortification studies of methyl mercury at 0.2 and 1.0 ppm levels. The applicability of aqueous methyl mercuric chloride solution for fortification studies was demonstrated.

Electron capture gas-liquid chromatographic determination of methyl mercury in fish and shellfish: collaborative study.

A method for determining methyl mercury in fish and shellfish was collaboratively studied in 8 laboratories. Methyl mercury is isolated from acetone-washed, homogenized tissue by adding hydrochloric acid and extracting into benzene the methyl mercuric chloride that is formed. The benzene extract is concentrated and analyzed for methyl mercuric chloride by electron capture gas-liquid chromatography on 5% DEGS-PS treated with inorganic mercuric chloride solution. The quantitation limit for the method is 0.05 micrograms Hg/g. Each collaborator determined methyl mercury at 2 levels in blind duplicate samples of swordfish, tuna, oyster, and shrimp tissues. Both fortified and unfortified samples were analyzed. Methyl-bound mercury in the samples ranged from 0.15 to 2.48 micrograms Hg/g. The reproducibility coefficients of variation for the 8 samples ranged from 3 to 13%. The accuracy, measured by comparison to reference values, ranged from 99 to 120%. Reference values were determined in the Associate Referee's laboratory by replicate analyses of the fortified and unfortified samples. The method has been adopted official first action.

Defining a lowest level of reliable measurement for lead in foods.

Procedures are outlined for defining and demonstrating a lowest level of reliable measurement for Pb in foods. The method of analysis studied was a dry ash sample mineralization with quantitation by differential pulse anodic stripping voltammetry at a hanging mercury drop electrode. Past experience with analyses for Pb in foods indicated that the lowest measurement of Pb in foods was limited by the Pb contributed from the reagents, apparatus, and laboratory environment. The magnitude of contamination from these 3 sources was investigated. Once a specific source of contamination was identified, attempts were made to eliminate or minimize the amount of Pb it contributed to the analysis. After contamination was controlled to the degree our facilities would allow, low level Pb determinations were performed on infant formula.

Determination of lead and cadmium in foods by anodic stripping voltammetry: I. Development of method.

Food samples are dry ashed at 500 +/- 50 degrees C with a 10% aqueous K2SO4 solution used as an ashing aid. The ashed sample is dissolved in 50 mL 2% HNO3. Anodic stripping voltammetry is used to determine lead and cadmium in a mixture of the sample solution and an acetate electrolyte at pH 4.3 +/- 0.3. The estimated quantitation limits, based on a 10 g food sample, are 0.005 ppm for cadmium and 0.010 ppm for lead.

Determination of lead and cadmium in foods by anodic stripping voltammetry: II. Collaborative study.

A dry ash anodic stripping voltammetric method for determining lead and cadmium in foods was collaboratively studied by 20 laboratories. The food commodities studied were strained green beans, beef (baby food), fish (mackerel), infant formula (milk base), apple juice, and cereal (wheat farina). Each collaborator analyzed 3 commodities, each consisting of 2 duplicate lead and cadmium fortification levels, for a total of 4 samples for each commodity. The low fortification levels ranged from 0.03 to 0.08 ppm for cadmium and from 0.05 to 0.15 ppm for lead. The high fortification levels ranged from 0.12 to 0.28 ppm for cadmium and from 0.24 to 0.45 ppm for lead. Each commodity was analyzed by 10 collaborators. The average overall reproducibilities of the low level fortifications were 24% for lead and 21% for cadmium; for the high level fortifications, average overall reproducibilities were 18% for lead and 16% for cadmium. The average accuracies of the collaborative results as measured by comparison to reference values were 96 and 97% for cadmium and lead, respectively. This method has been adopted official first action.

Concurrent exposure to lead, cadmium, and arsenic. Effects on toxicity and tissue metal concentrations in the rat.

Male rats were exposed to dietary Pb (200 ppm), Cd (50 ppm), or As (50 ppm) as arsenate either alone or in combination for 10 weeks using a 2 x 2 x 2 factorial design. Cd and As reduced weight gain even when differences in food intake were taken into account, and administration of both Cd and As depressed weight gain more than did either metal alone. Pb did not adversely affect food consumption or weight gain. Increased RBCs were observed after administration of Pb, Cd, or As, and more cells were observed when two or three metals were concomitantly administered. Despite increased numbers of circulating RBCs, hemoglobin and hematocrit were reduced, especially with the Pb-Cd combination. Analysis of blood chemistries showed normal ranges for blood urea nitrogen, creatinine, cholesterol, calcium, albumin, total protein, and bilirubin. Uric acid was increased by Pb, but not by Cd or As. SGOT activity was reduced by As alone. Serum alkaline phosphatase was reduced by either As or Cd but not Pb. Combinations of As and Cd did not further reduce the activity of this enzyme. Kidney weight and kidney weight/body weight ratios were increased by Pb alone, but Cd or As alone or in combination had no effect. Liver weight/body weight ratios were reduced in animals fed Cd. Kidney histology showed predominantly Pb effects, i.e., intranuclear inclusion bodies and cloudy swelling. Ultrastructural evaluation of kidneys from Pb-treated animals disclosed nuclear inclusion bodies and mitochondrial swelling. Concurrent administration of Cd reduced total mean bone and kidney Pb levels by 50% and 60%, respectively, and this was associated with a decrease in kidney intranuclear inclusions. Cd exposure also reduced renal, femur, and liver concentrations of Fe by 33%, 43%, and 63%, respectively, decreased femur Zn by 27%, but increased renal Zn by 20%. Administration of As produced mild swelling of tubule cell mitochondria, increased mean total renal Cu to 200% of control, and increased liver Fe by 44%. Dietary Pb produced increased urinary excretion of ALA and coproporphyrin. Dietary exposure to As caused increased urinary excretion of uroporphyrin and to a lesser extent coproporphyrin, whereas dietary Cd caused no significant changes in urinary levels of any of the porphyrins measured. Pb plus As produced an additive effect on coproporphyrin excretion but not that of ALA or uroporphyrin. These studies indicate that interactions between common toxic elements do occur and are characterized by alterations in both tissue trace metal levels and toxicity.