LEAD

Overview

CAS number

7439-92-1

Functional Class

Food Contaminant
METALS

Evaluations

Evaluation year: 2011

Comments:

The Committee considered the neurodevelopmental effects of lead to be pivotal in its assessment for children. Based on the results of a metaanalysis of epidemiological data, the chronic dietary exposure corresponding to a decrease of 1 IQ point was estimated to be 0.6 μg/kg bw/d (5th to 95th: percentiles 0.2–7.2 μg/kg bw/d). For adults, the Committee concluded that the pivotal data were the increased systolic blood pressures. Based on the averaged median reference slope estimates for blood lead levels versus systolic blood pressure from 4 epidemiology studies, the dietary exposure corresponding to an increase in systolic blood pressure of 1 mmHg (0.1333 kPa) was estimated to be 1.3 (5th to 95th percentiles 0.6–28) μg/kg bw/d. Based on this analysis, the previously established PTWI of 25 mcg/kg bw is associated with a decrease of at least 3 IQ points in children and an increase in systolic blood pressure of approximately 3 mmHg (0.4 kPa) in adults. These changes are important when viewed as a shift in the distribution of IQ or blood pressure within a population. The Committee concluded that the PTWI could no longer be considered health protective, and it was withdrawn. Because the analyses do not indicate a threshold for the key effects of lead, the Committee concluded that it was not possible to establish a new PTWI that would be considered health protective. The Committee stressed that these estimates are based on dietary exposure (mainly food) and that other sources of exposure to lead also need to be considered.

Intake:

Adults: 0.02-3 μg/kg bw/d (mean), 0.06-2.43 μg/kg bw/d (90th to 97.5th percentile). Children: 0.03 to 9 μg/kg bw/d (mean), 0.2 to 8.2 μg/kg bw/d (90th to 97.5th percentile). Dietary exposure < exposure from air, water, soil and paint for many people. Reported declines in lead consumption from food 75-95%.

Tolerable Intake:

Previously established PTWI withdrawn. Not possible to establish a new PTWI that would be considered health protective

Meeting:

Report:

TRS 960-JECFA 73

Tox Monograph:

73rd_2011_Lead.pdf

Toxicological study

Pivotal Study:

Children (Lanphear et al., 2005): Metaanalysis of 1333 children enrolled in seven longitudinal cohort studies conducted in the USA, Mexico, Kosovo and Australia, who were followed from birth or early infancy to 5–10 years of age. Adults (combined results of Glenn et al., 2003,, Vupputuri et al., 2003, Nash et al., 2003, Glenn et al., 2006)

Animal Specie:

Human

Effect:

Neurodevelopment (children) and systolic blood pressure (adults)

NOAEL:

None

PTWI:

Previously established PTWI withdrawn

Point of departure:

0.6 µg/kg/d loss of 1 IQ point in children;1.2 µg/kg bw/d for 1 mmHg increase in blood pressure (adults)

Evaluation year: 1999

Comments:

The provisional tolerable weekly intake (PTWI) of 0.025 mg/kg bw was maintained at the fifty-third meeting (1999). The Committee considered the results of a quantitative risk assessment and concluded that the concentrations of lead found currently in food would have negligible effects on the neurobehavioural development of infants and children. The Committee noted, however, that examples of foods with high levels of lead remain in commerce. The simulation model that is presented in the report could be used to evaluate the effects of any proposed regulatory interventions to reduce exposure to lead. A full risk assessment of dietary intake of lead should also take into account other sources of exposure.

Tolerable Intake:

PTWI 0.025 mg/kg bw

Meeting:

Report:

TRS 896-JECFA 53/81

Tox Monograph:

FAS 44-JECFA 53/273

Previous Years:

1993, TRS 837-JECFA 41/32, FAS 21-JECFA 30/223 (1986). PTWI 0.025 1986, TRS 751-JECFA 30/35, FAS 21-JECFA 30/223. PTWI 0.025 (EVALUATION OF HEALTH RISK TO INFANTS AND CHILDREN; REFERS TO LEAD FROM ALL SOURCES) 1978, TRS 631-JECFA 22/26, FAS 13-JECFA 22/