Provisional Tolerable Weekly Intake Research Articles

Dietary exposure of the Korean population to arsenic, cadmium, lead and mercury

Due to increasing concern about the intake of contaminants in foods, this study was performed to monitor the exposure of the Korean population to heavy metal contaminants (arsenic, cadmium, mercury and lead) from typical diets, and to estimate the health risk. A food list representing typical dietary practices of Koreans was developed, based on the results of the 1998 National Health and Nutrition Survey and the 1999 Seasonal Nutrition Survey, which included a nationwide sample of 4000 and 3000 households, respectively, including everyone 1 year and older. Foods were prepared for consumption (table-ready) according to representative recipes and typical cooking methods, and were chemically analysed to measure the levels of heavy metals by inductively coupled plasma–emission spectrometry (arsenic, cadmium and lead) and gold amalgamation (mercury). Then, the dietary intake of each heavy metal was estimated based on the mean food intake of the population, and the associated risk was evaluated by comparing intakes with the provisional tolerable weekly intakes (PTWIs). Although seaweeds and fishes were highest in heavy metal content, the contribution of foods to total heavy metal intake was more influenced by the amount of food consumed, so that cooked rice was the most important contributor to mercury intake, and vegetables the most important contributor of lead. Nevertheless, the estimated dietary intakes of arsenic (38.5 μg/person/day), cadmium (14.3 μg/person/day), lead (24.4 μg/person/day) and mercury (1.61 μg/person/day) from the 116 foods tested were well within the safe limits (under 30% of PTWIs). It appears that there is no imminent health risk due to heavy metals examined in this study for the total diet of the Korean population.

Essential and Toxic Elements in Seafood Available in Poland from Different Geographical Regions

The concentrations of 15 elements (Cu, Fe, Mn, Zn, Co, Ni, Cr, Se, Cd, Pb, Hg, Ca, Na, K, and Mg) were determined in the edible parts of shellfish on sale in the local market in Gdańsk. The samples consisted of three groups--crustaceans, molluscs, and surimi--that are processed to different degrees. For the purposes of this analysis, they were dried, homogenized, and digested in an automatic microwave system. The samples were analyzed quantitatively for Cu, Zn, Fe, Mn, Co, Ni, Cr, Mg, Na, K, and Ca (F-AAS), Cd and Pb (GF-AAS), Se (HG-AAS), and Hg (CV-AAS). The elemental levels detected in shellfish were compared to those in cod, herring, pork, beef, chicken, and eggs. The recommended dietary allowance (RDA) of essential elements and the provisional tolerable weekly intake (PTWI) of toxic elements were estimated. With factor analysis of the data, taxonomically different groups of raw and processed shellfish could be distinguished.

Intake of arsenic from water, food composites and excretion through urine, hair from a studied population in West Bengal, India

To evaluate the main intake source of arsenic by the villagers from arsenic-affected families in Jalangi and Domkol blocks in Mushidabad district, West Bengal—India, we determined the concentrations of arsenic in tubewell water and in food composites, mainly including vegetables and cereals collected from the surveyed families which were cultivated in that region. The daily dietary intakes of arsenic by the villagers were estimated and the excretions of arsenic through urine and hair were determined. The arsenic concentrations in hair and urine of the studied population living in mild (2.78 μg/L), moderate (30.7 μg/L) and high (118 μg/L) arsenic-affected families were 133, 1391 and 4713 μg/kg and 43.1, 244 and 336 μg/L, respectively. The linear regressions show good correlations between arsenic concentrations in water vs hair ( r 2 = 0.928, p < 0.001) and water vs urine ( r 2 = 0.464, p < 0.01). Approximately 29.4%, 58.1% and 62.1% of adult population from mild, moderate and high arsenic-affected families were suffering from arsenical skin manifestations. The mean arsenic concentrations of food composites (vegetables and cereals) in high arsenic-affected families are not significantly different from mild arsenic-affected families. The daily dietary intakes of arsenic from water and food composites of the studied population, living in high, moderate and mild arsenic-affected families were 568, 228 and 137 μg, respectively. The linear regressions show good correlations between arsenic concentrations in hair vs daily dietary intake ( r 2 = 0.452, p < 0.001) and urine vs daily dietary intake ( r 2 = 0.134, p < 0.001). The water for drinking contributed 6.07%, 26.7% and 58.1% of total arsenic in our study from mild, moderate and high arsenic-affected families. The result suggested that the contaminated water from high arsenic-affected families should be the main source for intake of arsenic. On contrary, the contribution of arsenic-contaminated food composites from mild and moderate arsenic-affected families might be the main source for intake of arsenic. The Food and Agriculture Organization/World Health Organization (FAO/WHO) provisional tolerable weekly intake (PTWI) values of arsenic in our study were 3.32, 5.75 and 12.9 μg/kg body weight/day from mild, moderate and high arsenic-affected families, respectively, which is higher than the recommended PTWI value of arsenic (2.1 μg/kg body weight/day).

Incomplete Generalized U‐Statistics for Food Risk Assessment

This article proposes statistical tools for quantitative evaluation of the risk due to the presence of some particular contaminants in food. We focus on the estimation of the probability of the exposure to exceed the so-called provisional tolerable weekly intake (PTWI), when both consumption data and contamination data are independently available. A Monte Carlo approximation of the plug-in estimator, which may be seen as an incomplete generalized U-statistic, is investigated. We obtain the asymptotic properties of this estimator and propose several confidence intervals, based on two estimators of the asymptotic variance: (i) a bootstrap type estimator and (ii) an approximate jackknife estimator relying on the Hoeffding decomposition of the original U-statistics. As an illustration, we present an evaluation of the exposure to Ochratoxin A in France.

Lead levels in retail samples of Spanish infant formulae and their contribution to dietary intake of infants

Lead concentrations in 82 different types of infant formulae (cow's milk and soy based) marked in Spain were analysed by acid-microwave decomposition and anodic stripping voltammetry. Dietary lead intake from infant formula and tap water used for powder formula reconstitution were estimated in comparison with the provisional tolerable weekly intake (PTWI). Additionally, the influence of physical state (powder and ready-to-use formulae), the type of container used and the impact of the industrial process from different manufacturers on lead levels were evaluated. According to the results, lead exposure from drinking water was negligible with respect to formulae investigated; where soya formulae contributed the highest intake (58–73% PTWI), non-adapted starter and specialized formulae gave an moderate intake (31–42 and 26–37% PTWI, respectively), and, finally, pre-term, adapted starter and follow-up formulae provided the lowest lead intake (22–25, 22–26 and 16–22% PTWI, respectively). Based on the current state of knowledge about lead toxicity, manufacturers are called to make an additional effort in order to keep a maximum lead level at 20 µg l−1 for all infant formulae, although it is recommendable that these formulations supply the upper limit (5 µg l−1) of ‘normal' human milk.

Health risks of dietary intake of environmental pollutants by elite sportsmen and sportswomen

The dietary intake of arsenic (As), cadmium (Cd), mercury (Hg), lead (Pb), hexachlorobenzene (HCB), polychlorinated naphthalenes (PCNs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated diphenyl ethers (PCDEs), polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), and polychlorinated dibenzo- p-dioxins and dibenzofurans (PCDD/Fs) by elite sportsmen and sportswomen of Catalonia, Spain, was assessed. In 2000, food samples were randomly acquired in various cities of Catalonia. Analysis of the above pollutants were determined according to the appropriate analytical techniques (ICP-MS, HRGC/HRMS, HPLC). In general terms, elite sportsmen and sportswomen showed a higher intake of Cd, Hg, Pb, HCB, PCNs, PCDD/Fs and PAHs than the general population, while it was lower for PCDEs (both sexes), and PCBs and PBDEs (women). According to the FAO/WHO provisional tolerable weekly intake (PTWI) for metals, the WHO tolerable daily intake (TDI) for HCB, and the US EPA’s reference dose (RfD) for PAHs, the dietary intakes of environmental pollutants should not mean a potential toxic hazard. However, the WHO-TDI for PCDD/Fs and “dioxin-like” PCBs is exceeded in sportsmen. The current results indicate that the consumption of those food groups showing the highest contribution to the intake of these pollutants should be diminished. In relation to this, the reduction of the consumption of dairy products and cereals would be important.

Dietary exposure estimates of 18 elements from the 1st French Total Diet Study

To estimate the dietary exposure of the main minerals and trace elements from retail food typically consumed by the French population, samples were purchased and then prepared and cooked prior to analysis. A total of 1080 individual food composites samples were collected and analysed for 18 elements (arsenic, lead, cadmium, aluminium, mercury, antimony, chrome, calcium, manganese, magnesium, nickel, copper, zinc, lithium, sodium, molybdenum, cobalt and selenium). Intakes were calculated from different food consumption patterns found in France for average and high consumers among adults and children. Dietary exposures of those consumers estimated from the France 2000 Total Diet Study (FTDS) are reported, and compared with existing nutritional reference values (Lowest threshold Intake, LTI) or toxicological reference values (Provisional Tolerable Weekly Intake, PTWI or Upper Level, UL) of the respective element and from previous French studies. This study confirms for the populations concerned, the low probability of nutritional or health risks due to food consumption.

Assessment of trace elements in canned fishes (mackerel, tuna, salmon, sardines and herrings) marketed in Georgia and Alabama (United States of America)

The concentrations of mercury and 13 other trace metals in 104 canned fish samples purchased within the states of Georgia and Alabama (United States of America) were determined using the direct mercury analyzer (DMA) and the inductively coupled plasma-optical emission spectrometer (ICP-OES). The ranges obtained for the elements analyzed in mg/kg (wet weight) are as follows: Hg (0.02–0.74), Ag (0.0–0.20), As (0.0–1.72), Cd (0.0–0.05), Cr (0.0–0.30), Fe (0.01–88.4), Pb (0.0–0.03), Mn (0.01–2.55), Ni (0.0–0.78), Co (0.0–0.10), Cu (0.01–5.33), Sn (0.04–28.7), V (0.0–0.31) and Zn (0.14–97.8). Three tuna samples had Hg level above the European dietary limit of 0.5 mg Hg/kg. The mean Hg concentrations in the tuna (285 μg/kg) and sardine (107 μg/kg) brands were higher than the averages posted by the pink salmon (36.1 μg/kg), red salmon (32.8 μg/kg) and mackerel (36.4 μg/kg) brands. Two tuna samples and a sardine sample exceeded the Australian permissible limit of 1 μg/g inorganic arsenic (wet weight). Two samples (brand 15: herring) had zinc levels exceeding the Food and Agriculture Organization (FAO) recommended limit of 40 mg/kg and two pink salmons also exceeded the Brazilian regulatory limit of 0.1 mg Cr/kg. One tuna sample had a cadmium level slightly exceeding the Codex Committee on Food Additives and Contaminants draft guideline of 0.50 mg Cd/kg. However, the concentrations of lead, cadmium and copper were below the corresponding MAFF guidelines of 2.0, 1.0 and 30 mg/kg, respectively. Also, based on the United States Environmental Protection Agency (US EPA) health criteria for carcinogens, there are no health risks with respect to Pb, Cr, Cu and Zn concentrations in canned fishes analyzed. The result of the one-way analysis of variance (ANOVA) conducted on the data suggested that significant variations ( P < 0.05 ) existed in the concentrations of Hg, As, Co, Cr, Cu, Fe, Mn, Sn, V, and Zn across the various fish species and canned fish brands analyzed. The estimated weekly intakes of Hg, As, Cd, Pb, Sn, Fe, Cu and Zn for a 60 kg adult consuming 350 g of fish/week were below the respective provisional tolerable weekly intakes (PTWI) in μg/kg body weight for: Hg: 5; As: 15; Cd: 7; Pb: 25; Sn: 14000; Fe: 5600; Cu: 3500; and Zn: 7000.

Management options to reduce exposure to methyl mercury through the consumption of fish and fishery products by the French population

This paper presents an updated assessment of exposure in France to methyl mercury through the consumption of fish and fishery products, and proposes several management scenarios which could reduce this exposure through changes to fish contamination levels or fish consumption patterns. The exposure model was applied in line with previous methodological results [Tressou, J., Crépet, A., Bertail, P., Feinberg, M.H., Leblanc J.Ch., 2004a. Probabilistic exposure assessment to food chemicals based on extreme value theory: application to heavy metals from fish and sea products. Food Chem. Toxicol. 42, 1349–1358; Tressou, J., Leblanc, J.Ch., Feinberg, M., Bertail, P., 2004b. Statistical methodology to evaluate food exposure to a contaminant and influence of sanitary limits: application to ochratoxin A. Regul. Toxicol. Pharmacol. 40, 252–263] so as to obtain a realistic estimate of probability and confidence intervals (95% CI) concerning French consumers exposed to levels exceeding the revised fixed provisional tolerable weekly intake (PTWI) for methyl mercury of 1.6 μg/week/kg of body weight, established by the Joint FAO/WHO Expert Committee on Food Additives in 2003. The results showed that young children aged between 3 and 6 years old or 7 and 10 years old, and women of childbearing age were at the risk groups. With respect to these groups and according to the fish consumers patterns (consumers of predatory fish only or consumers of predatory and nonpredatory fish), the results suggested that strategies to diminish MeHg exposure by reducing the amount of predatory fish consumed would be more efficient in significantly decreasing the probability of exceeding the PTWI than the implementation of international standards.

Environmental assessment of mercury contamination from the Rwamagasa artisanal gold mining centre, Geita District, Tanzania

This study presents the results of an environmental assessment of mercury (Hg) contamination in the Rwamagasa artisanal gold mining area, northwest Tanzania, and the potential downstream dispersion along the River Malagarasi to Lake Tanganyika. At the time of sampling, generally low concentrations of Hg (<0.05 mg/kg) occurred in most cultivated soils although higher Hg (0.05–9.2 mg/kg) was recorded in urban soils and vegetable plot soils where these are impacted by Hg-contaminated water and sediment derived from mineral processing activities. Hg in vegetable and grain samples is mostly below the detection limit of 0.004 mg/kg Hg, apart from 0.007 and 0.092 mg/kg Hg in two yam samples and 0.011 to 0.013 mg/kg Hg in three rice samples. The standardized (i.e., standardized to 10 cm length) Hg concentrations in Clarias spp. increase from about 0.01 mg Hg/kg for the River Malagarasi delta to 0.07, 0.2, and 1.6 mg/kg, respectively, for the Rwamagasa ‘background’, moderately and most contaminated sites. For piscivorous ( Lates, Brycinus, and Hydrocynus spp.), insectivorous ( Barbus spp.), and planktivorous ( Haplochromis spp.) fish species, the 10-cm standardized Hg concentrations increase from about 0.006 mg/kg for the River Malagarasi-Lake Tanganyika area to 0.5 and 3.5 mg/kg, respectively, for the Rwamagasa moderately and most contaminated sites. The low concentrations of Hg in fish from the Malagarasi River delta and Lake Tanganyika indicate that Hg contamination from the Rwamagasa area does not have a readily discernible impact on the biota of Lake Tanganyika. Many of the fish samples from Rwamagasa exceed guidelines for human consumption (0.5 mg/kg) as well as the WHO recommended limit for vulnerable groups (0.2 mg/kg). Tissue total Hg (THg) of all fish collected from the River Malagarasi-Lake Tanganyika subarea is well below these guidelines. Potential human exposure through consumption of 300 g/day of rice grown on Hg-contaminated soils is 5.5 μg/week. Consumption of 250 g Nile perch ( Lates spp.), 500 g tilapia ( Oreochromis spp.), and 250 g of catfish ( Clarias spp.) each week would result in an intake of 65 μg Hg/week for people consuming only fish from the Mara and Mwanza regions of Lake Victoria and 116 μg Hg/week for people in the Rwamagasa area consuming tilapia and Nile perch from Lake Victoria and catfish from mining-impacted streams. This is lower than the Provisional Tolerable Weekly Intake (PTWI) of 300 μg for Hg in the diet set by the WHO and the FAO. Inadvertent ingestion of soil containing 9 mg Hg/kg at a rate of 80 mg/day would give an additional estimated weekly intake of 5 μg THg, whereas the persistent and purposeful consumption of soil (geophagia) at a rate of 26 g soil/day would produce an additional chemical exposure of 230 μg Hg/day.

Ochratoxin A: Previous risk assessments and issues arising

Ochratoxin A (OTA) causes nephropathy in all species tested with large sex and species differences in potency, pigs being most sensitive. It has been linked to Balkan endemic nephropathy (BEN) in humans. Embryotoxicity, teratogenicity, and immunotoxicity occur only at doses higher than those causing nephrotoxicity. OTA has long serum half-lives in various species including humans. OTA produced renal tumours in mice and rats. The male rat was most sensitive, renal carcinomas occurring after 70 µg/kg bw per day but not 21 µg/kg bw per day. OTA was not mutagenic in most studies in bacteria and mammalian cells, but produced DNA damage and chromosomal aberrations in mammalian cells in vitro, and in mice in vivo. DNA adducts found in the kidneys of mice and rats dosed with OTA, did not contain fragments of OTA. OTA in food has been evaluated by the Joint FAO/WHO Expert Committee on Food Additives (JECFA), and by the EC Scientific Committee on Food (SCF). JECFA established a provisional tolerable weekly intake (PTWI) of 100 ng/kg bw based on the LOEL for renal effects in pigs. Conversely, SCF recommended reducing exposure to OTA as much as possible, e.g. below 5 ng/kg bw per day. Both committees recommended further studies to clarify the mechanism by which OTA induces nephrotoxicity and carcinogenicity.

Human Exposure to Metals Through the Diet in Tarragona, Spain: Temporal Trend

The concentrations of arsenic (As), beryllium (Be), cadmium (Cd), chromium (Cr), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb), tin (Sn), thallium (Tl), and vanadium (V) were determined in a number of food items purchased in zones of Tarragona County (Catalonia, Spain) near a hazardous waste incinerator (HWI), which has been operating since 1999. Food samples corresponded to the following groups: meat, fish and seafood, pulses, cereals, vegetables, fruits, tubers, whole milk, yogurt, eggs, and sugar. Be and Tl were under their respective limits of detection in all samples. For the analyzed trace elements, the dietary intake by the general population of Tarragona was 458.5 microg/d for As, 14.3 microg/d for Cd, 88.3 microg/d for Cr, 5.3 microg/d for Hg, 2421.4 microg/d for Mn, 138.3 microg/d for Ni, 44.8 microg/d for Pb, 34.6 microg/d for Sn, and 28.9 microg/d for V. Results were compared with those found in a baseline survey carried out in the same area during the construction of the HWI (1996-1998). In general terms, the dietary intake of metals in 2003 was comparatively similar to those found in the baseline survey. For the most toxic elements (As, Cd, Hg, and Pb), it was under their respective Provisional Tolerable Weekly Intake (PTWI) established by the FAO/WHO.

Some recent advances in modelling dietary exposure to ochratoxin A

One of the key questions when assessing the exposure to contaminants is the choice of the method and the impact of this choice on the result to be compared with the toxicological reference value. This problem is particularly significant in the case of ochratoxin A (OTA) for which the use of crude estimates can provide results close to the current provisional tolerable weekly intake (PTWI). This paper compares different exposure assessment models for OTA using the same data set for food consumption (i.e. French INCA survey 1999) for the same groups of the population (i.e. adults excluding under-reporters and children 3–14 years-old) but with various ways of handling the occurrence of OTA in food. The consumption and contamination data were combined through 11 different scenarios based on parametric and non-parametric modelling and on the use of analytical results obtained on raw commodities or on foodstuffs ready-to-eat. In order to assess exposure to OTA using data on consumption of processed and composite foods it was necessary to use recipe information in order to utilize available contamination data which only exists for raw materials. The impact of such an adjustment appears to be essential to avoid an overestimation of the exposure. The impact of the other assumptions and the choice of mathematical models influence the results less but should be considered and detailed carefully in future dietary exposure assessments.

Consumption of homegrown products does not increase dietary intake of arsenic, cadmium, lead, and mercury by young children living in an industrialized area of Germany

The dietary intake of arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb) was studied among young German children with different food consumption behaviour (consumption of own grown foodstuffs and of products from the supermarket). The study area comprised an industrialized and a rural area of West Germany. Dietary intake of contaminants was measured by the duplicate method according to the WHO guideline. A total 588 duplicate portions were collected daily from 84 individuals between May and September 1998. Intake of food groups was calculated from dietary records. Determination of As, Cd, Hg, and Pb was performed following high-pressure digestion of lyophilized samples by atomic absorption spectrometry (AAS). Geometric mean weekly intake [μg/(kg bw·week)] was as follows: As 1.4, Cd 2.3, Hg 0.16, and Pb 5.3. Geometric mean intake corresponded to the percentage of the provisional tolerable weekly intake (PTWI) as follows: As 9.7%, Cd 32%, Hg 3.3%, Pb 21%. As and Hg intake were mainly influenced by fish consumption. The amount of cereals and bakery wares mainly determined the Cd and Pb intake. Children living in the industrialized area with a substantial food consumption of own grown vegetables or products from domestic animals products had no increased dietary intake of the metals.

Exposure assessment of lead among Japanese children.

Lead intake from possible exposure routes among children residing in the Tokyo Metropolitan Area was estimated. Lead concentrations in house dust samples collected from the houses of the children and those in 24-h duplicate diet samples of the children were determined. The daily lead intake was estimated by multiplying the lead concentrations in the house dust, diet, soil and ambient air (the latter two were from the literatures) by the corresponding intake and/or inhalation rates, and summing all of the products. Bioaccessibility tests were performed on the house dust, soil and diet samples to determine the lead uptake level. Children residing in the Tokyo Metropolitan Area were estimated to be exposed to 21.5 μg of lead on a daily basis, with a maximum intake of up to 70.4 μg. The average weekly intake per kg body weight for a 5-year-old Japanese child was found to be 8.0 μg/kg bw/wk, which is below the Provisional Tolerable Weekly Intake (PTWI) of 25 μg/kg bw/wk. However, the maximum weekly intake was found to be 26 μg/kg bw/wk. House dust and soil ingestion can be the predominant routes of exposure to lead among children in Japan, and the source(s) of lead in such media must be specified to reduce the lead intake level of the children.

Environmental exposure and preventive measures in Sweden and EU*

Environmental exposure to cadmium (Cd) gives rise to renal tubular dysfunction at low cumulative doses of Cd. A possible role of Cd in influencing the occurrence of diseases, e.g., bone, reproductive and cancer in the general population groups environmentally exposed to Cd has been reported from Japan, Belgium, Sweden and China. Authorities have to pay attention to this fact and to act in order to prevent serious outcomes and personal suffering in the population groups at risk. A general approach in setting recommended health based limits and to regulate the occurrence of a substance existing in food stuff is to keep low levels -better to be on the safer side than on the risk side. In the case of cadmium it should be most clear that since cadmium has a very long biological half-life of 20 years in humans, increased cadmium exposure due to human activities can never be accepted. In cases where cadmium exposure can not be avoided the approach should be to limit and decrease exposure. Presently FAO/WHO Expert Committee on Food Additives and Food has a PTWI (provisional tolerable weekly intake) value for adult persons of 7 microg/kg body weight for Cd (WHO 2003) a value corresponding to 1 microg/kg body weight for each day of a week. For children and pregnant or lactating women daily intakes should not exceed 1 microg/kg body weight.

Combined toxic effects of mycotoxins

It is known for many years that several food items, derived from plants infected by fungi in the field during growing of the plant or during harvest and storage of the food item, can contain concomitantly different mycotoxins. As these combined mycotoxins occur simultaneously in the food item, consumption of the food will lead to a combined intake depending on the absorption rates of the different mycotoxins. Therefore, the question is justified whether such a combined intake of mycotoxins would lead to a possible higher risk for adverse health effects than the intake of one of these mycotoxins alone. It will be dealt with on the basis of some practical cases of such combined intake of mycotoxins of which research data are available. This is the case for citrinin and ochratoxin A, but as the workshop focuses on trichotecenes and so this paper concentrates on these. When the mycotoxins are of similar structure and of the same species, or of the same families, it is likely to expect that the mode of action of the mycotoxins and or the toxicity profiles will be quite similar. This indicates that such related mycotoxins are likely to exert only additive effects, which is important to know. In terms of risk assessment, these mycotoxins could be dealt with by establishing a group daily tolerable intake (TDI) or a provisional tolerable weekly intake (PTWI). In terms of risk assessment those mycotoxins which interact in synergistic manner are of more concern. It is concluded that, at present tools are not fully developed to establish the type of interaction or whether there is any interaction at all.

Assessment of Slovak population exposure to lead

Exposure of the Slovak Republic population to lead from food and drinks was studied. Calculations were done using 150,000 food, plant and animal raw materials, and drinks sampled in 1986–2002. Estimates of exposure to lead from actual and model consumption patterns were calculated for an average inhabitant and compared with the provisional tolerable weekly intake (PTWI) value. Existing knowledge and experience from projects run since 1991, as well as information from the database of the Centre for Evaluation of Contaminant Occurrence, located at the Food Research Institute in Bratislava, were utilized. The estimated exposure of the population to lead seems to be persistently low with a tendency to a slight decrease, especially in recent years. The exposure doses estimated for the last 6 years using the mean and median values show that the weekly intake of lead from food and drinks represents 22.3 to 14.1% PTWI and 12.2 to 7.2% PTWI, respectively.

Probabilistic exposure assessment to food chemicals based on extreme value theory. Application to heavy metals from fish and sea products

This paper presents new statistical methods in the field of exposure assessment. We focus on the estimation of the probability for the exposure to exceed a fixed safe level such as the provisional tolerable weekly intake (PTWI), when both consumption data and contamination data are independently available. Various calculations of exposure are proposed and compared. For many contaminants, PTWI belongs to the exposure tail distribution, which suggests the use of extreme value theory (EVT) to evaluate the risk. Our approach consists in modelling the exposure tail by a Pareto type distribution characterized by a Pareto index which may be seen as a measure of the risk of exceeding the PTWI. Using propositions by EVT specialists, we correct the bias of the usual Hill estimator to accurately estimate this risk index. We compare the results with an empirical plug-in method and show that the Pareto adjustment is relevant and efficient when exposure is low compared to the PTWI while the plug-in method should be used when exposure is higher. To illustrate our approach, we present some exposure assessment for heavy metals (lead, cadmium, mercury) via sea product consumption.

Mercury speciation in the muscle of two commercially important fish, hake ( Merluccius merluccius) and striped mullet ( Mullus barbatus) from the Mediterranean sea: estimated weekly intake

Total mercury and methylmercury concentrations were measured in the muscle tissue of two fish species from the Ionian and Adriatic seas. Higher total mercury and methylmercury concentrations were detected in striped mullet ( Mullus barbatus), a benthic species (Ionian sea: Hg=0.40 μg g −1 wet wt, MeHg=0.40 μg g −1 wet wt; Adriatic sea: Hg=0.49 μg g −1 wet wt, MeHg=0.44 μg g −1 wet wt), than in hake ( Merluccius merluccius), a pelagic species (Ionian sea: Hg=0.09 μg g −1 wet wt, MeHg=0.09 μg g −1 wet wt; Adriatic sea: Hg=0.18 μg g −1 wet wt; MeHg=0.16 μg g −1 wet wt). Total mercury residues were determined in all samples of both species from the Adriatic sea, while levels below the limit of detection were registered in 25% and 11%, respectively, of striped mullet and hake samples from the Ionian sea. In 18.8% and 22.2% of striped mullet samples from the Ionian and Adriatic seas, respectively, total mercury concentrations exceeded the maximum level fixed by the European Commission Decision (Hg=0.5 μg g −1 wet wt). In the two different species, mercury was present almost completely in the methylated form with mean percentages between 60% and 100%. The estimated weekly intake for total mercury was below the established the provisional tolerable weekly intake (PTWI) for both species, though their consumption provides a methylmercury intake above the WHO safety limit.