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I H von Lindern

Publications and source records attributed to I H von Lindern.

4 recordsLinked to original sources
PubMed1990

Lead-induced anemia: dose-response relationships and evidence for a threshold.

We conducted a cross-sectional epidemiologic study to assess the association between blood lead level and hematocrit in 579 one to five year-old children living near a primary lead smelter in 1974. Blood lead levels ranged from 0.53 to 7.91 mumol/L (11 to 164 micrograms/dl). To predict hematocrit as a function of blood lead level and age, we derived non-linear regression models and fit percentile curves. We used logistic regression to predict the probability of hematocrit values less than 35 per cent. We found a strong non-linear, dose-response relationship between blood lead level and hematocrit. This relationship was influenced by age, but (in this age group) not by sex; the effect was strongest in youngest children. In one year-olds, the age group most severely affected, the risk of an hematocrit value below 35 percent was 2 percent above background at blood lead levels between 0.97 and 1.88 mumol/L (20 and 39 micrograms/dl), 18 percent above background at lead levels of 1.93 to 2.85 mumol/L (40 to 59 micrograms/dl), and 40 percent above background at lead levels of 2.9 mumol/L (60 micrograms/dl) and greater; background was defined as a blood lead level below 1.88 mumol/L (20 micrograms/dl). This effect appeared independent of iron deficiency. These findings suggest that blood lead levels close to the currently recommended limit value of 1.21 mumol/L (25 micrograms/dl) are associated with dose-related depression of hematocrit in young children.

Air Pollutants, Occupational↗
PubMed1988

Threshold effect in lead-induced peripheral neuropathy.

We previously demonstrated a negative correlation between blood lead level and motor nerve conduction velocity in 202 asymptomatic 5 to 9-year-old children living near a lead smelter in Idaho. Blood lead levels ranged from 13 to 97 micrograms/dL. To determine whether a threshold exists between blood lead level and maximal motor nerve conduction velocity, we conducted three regression analyses on these data: a "hockey stick" regression, a logistic regression, and a quadratic regression. We found evidence for a threshold in all three analyses: at a blood level of 30 micrograms/dL in the "hockey stick" regression, at 20 micrograms/dL in the logistic, and at 25 to 30 micrograms/dL in the quadratic. Neither age, sex, socioeconomic status, nor duration of residence near the smelter significantly modified the relationship. These analyses confirm that asymptomatic increased lead absorption causes slowing of nerve conduction, but they also indicate that measurement of maximal motor nerve conduction velocity is an insensitive screen for low-level lead toxicity.

Child↗
PubMedDate not supplied

Age-specific risk factors for lead absorption in children.

The relationship of blood lead levels to environmental and individual characteristics is analyzed in a large sample of children residing near a lead smelting complex, with particular emphasis on the identification of age-related risk factors. Exceptional variation in both blood leads and its determinants within the study region facilitated the simultaneous detection of several significant risk factors for each year of age from 1 to 9 yr. The strongest predictor of blood lead at all ages was air lead, but the secondary risk factors were age dependent. Household dustiness was significantly related to blood lead in young children, especially those under 2 yr of age; soil lead may be an important source of ingested lead for children between 2 and 7 yr. Other significant effects included that of pica at about 2 yr of age, a slight effect of the occupational category of the fathers of 5- to 8-yr-old children, and a tendency for 8- and 9-yr-old boys to have higher blood leads than girls of the same age. Lead concentration in household paint was not a significant risk factor. These results suggest that a multifactorial approach to the prevention of excessive lead absorption by children is required.

Age Factors↗