Provisional Tolerable Daily Intakes

The provisional tolerable daily intake (TDI) values proposed by the European Food Safety Authority (EFSA 2008) and Health Protection Agency (HPA 2009) amount to 150 ng/kg body weight (bwt)/d and 300 ng/kg bwt/d, for PFOS and PFOA, respectively. 

The elevated toxaphene levels in Lake Superior have social and economic impacts as well. The 2003 Guide to Eating Sport Fish published by the Ontario Ministry of Environment and Energy [158] indicates fish consumption advisories for Lake Superior lake trout due to toxaphene levels. As a result of the high toxaphene levels, the Ontario Ministry of Natural Resources has restricted sale with Ontario (but not the export) of large lake trout harvested from Lake Superior as of 1995. An assessment of toxaphene levels in Lake Superior fish fillets by Health Canada concluded that consumption of lake trout, salmon, longnose sucker and whitefish muscle from northwestern areas of the lake should be limited to one or two meals per month (55-135 g/week) based on a provisional tolerable daily intake of 0.2 pg/g body wt/day [159]. 

The risk to health from chemicals in food can be assessed by comparing estimates of dietary exposure with recommended safe levels of exposure. For most metals and other elements, these are the Provisional Tolerable Weekly Intakes (PTWIs) and the Provisional Tolerable Daily Intakes (PTDIs) recommended by the Joint Expert Committee on Food Additives of the Food and Agricultural Organisation of the United Nations and the World Health Organisation International Programme on Chemical Safety (JECFA). The European Commission s Scientific Committee on Food has established other relevant safe levels. These are Acceptable Daily Intakes (ADIs) for chemicals added to food, and Tolerable Daily Intakes (TDIs) for chemical contaminants. The use of the term tolerable implies permissibility rather than acceptability. All the above recommendations are estimates of the amount of substance that can be ingested over a lifetime without appreciable risk, expressed on a daily or weekly basis as appropriate. 

It can be seen from Table 7.4 that the population dietary exposure to total arsenic for UK consumers has remained fairly constant. The dietary exposures for mean and 97.5th percentile adult UK consumers in 1997 were 0.12 mg/day and 0.42 mg/day respectively. Although these exposures are similar or greater than the JECFA Provisional Tolerable Daily Intake (PTDI) for inorganic arsenic of 0.002 mg/kg bodyweight, which is equivalent to 0.12 mg/day for a 60 kg person, these are estimated for total arsenic. As has been stated before, most of the arsenic in the diet is from fish and most of the arsenic in fish is in the less toxic organic forms. 

Patulin Inadequate Inadequate Class 3 (not classifiable Provisional tolerable daily intake ... 

An assessment of the dietary exposure to patulin in Europe showed that as far as the comparison with the provisional tolerable daily intake of 0.4 pg/kg of body weight/day is concerned, from the data reported, the exposure seems to be quite below that value (European Commission... 

Abbreviations EPA, Environmental Protection Agency ATSDR, Agency for Toxic Substances and Disease Registry FDA Food and Drug Administration NOAEL no-observed-adverse-effect level LOAEL, lowest-observed-adverse-effect level UF, uncertainty factor SF, safety factor RfD, reference dose (an amount of a substance that is anticipated to be without adverse health effects in humans, including sensitive populations, when ingested daily over a lifetime MRL, minimal risk level (an estimate of daily human exposure to a hazardous substance that is likely to be without an appreciable risk of adverse noncancer health effects over a specified route and duration of exposure) pTDI, provisional tolerable daily intake (maximum daily exposure level to a contaminant provisional meaning that it is considered temporary until more data are available, especially the completed Seychelles study) JECFA, Joint FAO/WHO Expert Conunittee on Food Additives pTWl, provisional tolerable weekly intake. 

This value is in the same range as the provisional tolerable daily intake of 0.035 mg lupin alkaloids kg bw day derived by ANZFA (Australia and New Zealand Food Authority) based on traditional use of lupin seeds. ANZFA cmicluded that traditional use of lupin seeds in Eiuope suggests that a daily dose of 0.35 mg lupin alkaloids kg bw (20 mg lupin alkaloids day ) can be tolerated in human adults without adverse effects. If an uncertainty factor of 10 is applied to accoimt for the uncertainties in the data and particularly to take into account likely human variatimi, the provisional tolerable daily intake for humans is 0.035 mg lupin alkaloids kg bw day [17]. 

For many substances the body s own mechanisms for de-toxification and repair mean that low doses of some chemicals can be tolerated without experiencing any adverse effects. However, once a certain threshold has been exceeded then the degree of adverse effect is related to the dose. The highest dose at which no adverse effects are observed in the most susceptible animal species is identified at the No Observed Adverse Effect Level (NOAEL). The NOAEL is used as the basis for setting human safety standards for contaminants, Provisional Tolerable Weekly Intakes (PTWIs) or Tolerable Daily Intakes (TDIs).1... 

Toxic and essential trace elements intakes were computed from food consumption data of the population in northern Italy and element concentration measurements. The results (Table 10.6) were compared with the Italian Recommended Dietary Allowance (RDA) for essential trace elements and with the Provisional Tolerable Daily/Weekly Intake (PTDI/PTWI) for toxic elements. Finally, an assessment was made of the extent to which each food contributes to the total intake of trace elements by the population under study and the most contaminated foods were also detected. On the whole, mean intake values satisfied the Italian RDA for all the essential trace elements [31], while the potentially toxic trace elements were below the relevant threshold limits. 

For contaminants and naturally occurring toxicants, levels corresponding to tolerable intakes such as the provisional maximum tolerable daily intake (PMTDI) or provisional tolerable weekly intake (PTWI) are established when there is an identifiable no-observed-effect level, that is, a threshold of effect can be assumed based on available data. When a noobserved-effect level cannot be identified, the Committee provides other advice, such as identification of the food(s) that contributes most to intake. This allows for targeted management actions in order to decrease exposure. 

Daily intake of Pb in humans is estimated to range from 20 mg to 400 mg per person. The FAO/WHO Expert Committee established a Provisional Tolerable Weekly Intake (PTWI) of 3000 mg, corresponding to ca. 500 mg/d. Only a half of this amount appears to be safe for children. About 5 to 15% of ingested Pb is absorbed. This amounts to 15 to 25 mg/d and represents two thirds of the total absorbed lead. By contrast, about 20 to 40% of the inhaled Pb is absorbed, amounting to about 8 mg/d, or one third of the total absorbed lead. 

The World Health Organization (WHO) has set a provisional tolerable weekly intake level for OTA at lOOng/Kg of body weight, taking its potentially carcinogenic effect into account (JEFCA, 2001). The tolerated maximum concentrations are based on a tolerable daily intake of 5 ng/(kg of body weight) suggested by the ED Scientific Committee on Food (Commission of the European Communities, 1998). CE... 

MTDI = maximum tolerable daily intake, or provisional maximum tolerable daily intake (PMTDI) a term used for description of the end point of contaminants with no cumulative properties. Its value represents permissible human exposure as a result of the natural occurrence of the substance in food or drinking water. In the case of trace elements that are both essential nutrients and unavoidable constituents of food, a range is expressed, the lower value representing the level of essentiality and the upper value the PMTDI. 

Overexposure to zinc by food, water, and air commonly poses no risk to the general population. Long-term administration of zinc (100-150 mg per day) to patients to promote wound healing is usually well tolerated, but anemia may be induced in case of low copper status. This effect is readily reversible, however. Using a safety factor of 10 this means that an additional zinc intake of 10-15 mg per day does not constitute a health hazard (US ERA 1980). The provisional maximum tolerable daily intake for man has been estimated at 0.3 to 1.0 mg Znkg body weight (WHO 1983). 

The FAO/WHO provisional tolerable weekly intake (PTWI) of 15 pg As kg body weight for a 60-kg man, when translated to a daily basis, is 2.1 pg kg per day (FAO/WHO 1989). The above estimated figures thus result in a range of about 0.78 pg kg per day for the average Japanese to about 0.18 pgkg per day for the average US American. This is, even for outliers, well below the PTWI. 

PMTDI (Provisional Maximum Tolerable Daily Intake) A provisional estimate of the amount of a hazardous substance with no cumulative properties in food or drinking water, expressed on a body-weight basis, that can be ingested daily over a lifetime without appreciable health risk. 

PTWI, Provisionably tolerable weekly intake PMTDI, Provisionably maximum tolerable daily intake PDDR, Provisionably daily dietary requirement. 

PMTDI Provisional Maximum Tolerable Daily Intake... 

PMTDI provisional maximum tolerable daily intake... 

It must be noted that the international regulatory organizations (World Health Organization (WHO), European Union (EU)/EFSA, the US EPA, etc.) have not established safety limits yet for PFC in drinking water. However, recently, Schriks et al. [106] derived provisional drinking water guideline values for PFOS and PFOA of 0.5 and 5.3 p.g/1, respectively, on the basis of the tolerable daily intake (TDI) values proposed by EFSA (2008). 

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