Prenatal exposure to the organophosphate pesticide chlorpyrifos and childhood tremor.

BACKGROUND: The organophosphate insecticide chlorpyrifos (CPF), widely used for agricultural purposes, has been linked to neurodevelopmental deficits. Possible motor effects at low to moderate levels of exposure have not been evaluated. METHODS: Prenatal exposure to CPF was measured in umbilical cord blood in a sample of 263 inner-city minority children, who were followed prospectively. At approximately 11 years of age (mean age 10.9 ± 0.85 years, range=9.0-13.9), during a neuropsychological assessment, children were asked to draw Archimedes spirals. These were rated by a senior neurologist specializing in movement disorders who was blind to CPF exposure level. RESULTS: Compared to all other children, those with prenatal CPF exposure in the upper quartile range (n=43) were more likely to exhibit mild or mild to moderate tremor (≥ 1) in either arm (p=0.03), both arms (p=0.02), the dominant arm (p=0.01), and the non-dominant arm (p=0.055). Logistic regression analyses showed significant CPF effects on tremor in both arms, either arm, the dominant arm (p-values <0.05), and the non-dominant arm (p=0.06), after adjustment for sex, age at testing, ethnicity, and medication. CONCLUSION: Prenatal CPF exposure is associated with tremor in middle childhood, which may be a sign of the insecticide's effects on nervous system function.

Tremor in a population-based cohort of children in New York City.

BACKGROUND: There have been virtually no surveys of the prevalence, clinical features, or correlates of tremor in children and none in the United States. METHODS: A total of 317 children (age 11.0 ± 1.1 years; range, 9.0 to 14.7) underwent an evaluation at one time point. Each drew Archimedes spirals, which were rated by a senior neurologist specializing in movement disorders. RESULTS: A spiral score of 1 (mild but consistent tremor) was present in either hand in 105 (33.1%) children; a higher score (1.5, mild-to-moderate tremor) was present in either hand in 7 (2.2%) children. Higher spiral scores were associated with poorer motor hand function as assessed using the Purdue Pegboard test. Spiral scores were higher in boys than girls, were inversely associated with age, and were higher in the nondominant than dominant hand. Spiral scores were highest in children who were taking psychiatric medications and in children with psychiatric or neurological disorders. CONCLUSIONS: Mild tremor is common in children and covaries significantly with several demographic and clinical factors as well as usage of certain medications. It also lessens with advancing age. Rather than an isolated finding, tremor was associated with other measures of poorer motor hand function.