Intake of lead

Lead enters the body through inhalation and ingestion, is absorbed into the circulatory system from the lungs and digestive tract, and excreted via the urine and feces. Normally, intake of lead approximately equals output. However, excessive exposure and intake can cause tissue concentrations to increase to the point where illness can result. 

Daily Average Intake of Lead 5-4 Ongoing Studies on Lead... 

Between 1979 and 1989 there was a virtual elimination of the use of lead-soldered food cans, with a concomitant drop in lead levels in food. Average daily intakes of lead for adults, based on an analysis of 27 market basket samples taken nationwide for a 1980-1982 Total Diet Study, were as follows (Gartrell etal. 1986b) ... 

Table 5-3. Daily Average Intake of Lead ( jg lead/day)...

In 1982-1983, the baseline value for daily intake of lead by inhalation in a nonurban environment was estimated to be 0.5 pg/day for a 2-year-old child. The baseline value was based on an average atmospheric lead concentration of 0.1 pg/m3 and an indoor/outdoor lead concentration ratio of 0.5. In an urban environment, the indoor/outdoor ratio was assumed to be approximately 0.8 (EPA 1986a). Drastic reductions in the lead content of gasoline since 1986 have resulted in a 64% decrease in lead emissions to the atmosphere (see Section 5.4.1). 

Dabeka RW, McKenzie AD, Lacroix GMA. 1987. Dietary intakes of lead, cadmium, arsenic and fluoride by Canadian adults A 24-hour duplicate diet study. Food Addit Contam 4 89-102. 

Ryu JE, Ziegler EE, Nelson SE, et al. 1983. Dietary intake of lead and blood lead concentration in early infancy. Am J Dis Child 137 986-891. 

The estimated average dietary intake of lead in humans is 300 pgday-1. Fortunately, only 8% of ingested lead is retained in the body. About 90% of the accumulated lead is localized in bone9. Organolead compounds, however, scarcely accumulate in bone138. 

Galal-Gorchev, H. (1993). Dietary intake, levels in food and estimated intake of lead, cadmium, and mercury. Food Addit. Contam., 10, 1, 115-128. 

To deal with this problem the EPA invested in the development and validation of a pharmacokinetic model that is capable of relating intake of lead to blood level. The model also allows the risk assessor to develop blood level estimates that integrate all sources of exposure. Using this model, it becomes possible to determine whether a specific source, such as our suspect water supply, is leading to exposures in excess of the target for all sources combined (this assumes that other sources do not contain levels of lead greater than normal, background... 

Tables 2.4 and 2.5 provide estimates of intake based on the average of the lead concentrations in Table 2.1 and kidney consumption distributions summarised in Tables 2.2 and 2.3. Intake figures tend to follow food consumption patterns although for pork kidney the intake is zero because no lead was detected in it. As expected, when calculated on a per person per week basis children have lower intakes of lead than do adults. However, when consumption is corrected for individual bodyweight, as is necessary for comparison with a PTWI, children s intake of all lead is about three times that of...

Table 2.4 Potential intakes of lead from kidney by UK adults...

The results in Table 7.8 indicate that the organ- and endpoint-specific risk indexes are about 0.7 to 0.8 in all cases, due mainly to intakes of lead. The maximum risk index for any organ or endpoint is about 0.8. Truncating this result using the INTEGER function, as indicated in Equation 6.5, gives a risk index for all deterministic hazardous chemicals in the waste of zero. This result means that the calculated dose in all organs and for all endpoints due to exposure to all deterministic substances that cause deterministic responses in the waste is less than the assumed acceptable dose of 10 times RfDs. Therefore, based only on consideration of substances that... 

The other major route of lead absorption is the gastrointestinal tract. Dietary intake of lead reached average peak values of almost 0.5 mg per person per day in the U.S. around the 1940s. Much of this lead came from lead solder used in cans employed for canned goods and beverages. Currently, daily intake of dietary lead in the U.S. is probably only around 20 pg per person per... 

Table 8.5 Sherlock s data for total dietary intake of lead in 1981...

Table 12.2 Dally dietary Intake of lead and cadmium Oig

The utilization of the macro element calcium is impaired by a high intake of lead, magnesium, aluminum and phytate, that of magnesium by lead, calcium, nickel, and phytate, and that of phosphorus by magnesium, calcium, and phytate. Several experiments in animals have strikingly illustrated the importance of a trace element dietary balance in determining the safe intake of a particular macro, trace or ultratrace element (O Dell 1997, Griin et al. 

Age is an important determinant of lead metabolism (US EPA 1986), there being a higher absorption from the gastrointestinal tract in infants than in adults. Simultaneous intake of lead, calcium and/or phosphate may reduce the gastrointestinal absorption of lead (Heard and Chamberlain 1984, James etal. 1985). Milk is a major source of both calcium and phosphorus, but it seems to contain several components that counteract the expected effects of calcium and phosphate, and this may lead to an increased (rather than decreased) lead uptake. It is not known which factor might be responsible for the increased lead uptake. 

Sharrett AR, Carter AP, Orheim RM and Feinlieb M (1982a) Daily intake of lead, cadmium, copper, and zinc from drinking water the Seattle study of trace metal exposure. Environ Res 28 456-475. 

The total intake of lead by adults and children in the general populations varies greatly as to the relative contributions from individual sources (air, water, food, soil/ dust, and others) and is partly depended on life-style and socio-economic status. Additional intake of lead will take place in certain groups from the use of tobacco and alcoholic beverages (WHO, 1995). Occupational exposure to lead occurs in many countries, especially in those with developing industries and small home-based industries. 

The major sources of lead for infants and children are dust and soil, chips of lead paint, water and food (Lockitch, 1993). According to the US EPA in 2-year-old infants the intake of lead is 47% from food, 1% from air, 45% from dust, 6% from water and 1% from soil. Deficit of calcium, phosphate, selenium or zinc may result in increased lead absorption. Iron and vitamin D also affect absorption of lead (WHO, 1995). 

Table 16. Daily dietary intake of lead ((jLg/kg body weight) in the Czech Republic...

The assessment of the daily dietary intake of lead via maximum exposure scenario ... 

Data of the GEMS/Food Programme from Hungary on the mean weekly dietary intakes of lead in the period 1980-1984 were 11.3-14.0 p.g/kg body weight in adults and 11.6 p.g/kg body weight in infants (UNEP/FAOAVHO, 1992). 

The lead contents in human milk and reconstituted infant formula obtained from the Lactarium of the Paediatric Hospital in Bratislava are presented in Table 19. The calculated median intakes of lead from human milk and infant formula were similar and they represent 18.8 and 23.8% of PTWI, respectively. The calculated intake of lead by maximal oral exposure scenario via the human milk exceeded the PTWI level by 9. 8%. In the investigated group of 35 mothers, no significant relation between lead... 

The average weekly intake of lead via drinking water is determined by water composition, plumbing system and consumer behaviour. These factors vary considerably, not only between supply zones, properties and individual consumers, but also over time. 

As shown, a variation of 10 minutes in mean inter-use stagnation time, which is quite normal (Bailey found standard deviations up to 22 minutes, depending on household size), has considerable influence on the average weekly intake of lead via drinking water. Furthermore, this figure shows that by lowering the mean... 

Figure 3.8 shows that the average daily consiunption depends on household size. This implies that the average weekly intake of lead by a eonsiuner depends on the number of occupants sharing the same tap. 

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