Neurobehavioral effect

Hansen E, Meyer O. 1980. Neurobehavioral effects of prenatal exposure to parathion-methyl on rats. Acta Morphol Acad Sci Hung 28 210. 

Grasso P. 1988. Neurotoxic and neurobehavioral effects of organic solvents on the nervous system. Occupational Medicine State of the Art Reviews. 3 525-539. 

Neurobehavioral effects of dietary soy phytoestrogens. Neurotoxicol Teratol. 24 (1) 5-16. 

No neurobehavioral effects were seen in 288 randomly selected males who were occupationally exposed to lead as compared to 181 demographically similar controls (Ryan et al. 1987). The mean PbB level in the exposed workers was 40.1 pg/dL and that of the controls was 7.2 pg/dL. Nineteen tests of neuropsychological performance were conducted. The lead-exposed workers performed no differently from controls on all measures except psychomotor speed and manual dexterity. The authors discounted this difference due to the observation that conflicting results were obtained in two different tests of motor speed and manual dexterity and possible confounding effects of age. There was no evidence that history of previous very high exposure had any effect on performance. 

The literature on the neurobehavioral effects of oral exposure to lead in animals is extensive. Only those studies considered key to clarifying human health issues will be presented here. High levels of exposure to lead produce encephalopathy in several species, but blood lead data for this effect are generally not available. 

Recent studies have focused on neurobehavioral effects of exposure of the developing organisms to lead. Studies concerned primarily with the effects of prenatal exposure are presented in the section on developmental effects (Section 2.2.3. 6), while studies concerned primarily with postnatal exposure are discussed here. 

Neurobehavioral effects, measured in various discrimination reversal and operant learning tests, were observed in lead exposed rats. PbB levels in rats as low as 15-20 pg/dL were associated with slower learning and higher rates of inappropriate responses (Cory-Slechta et al. 1985 Jadhav and Areola 1997). Neurobehavioral alterations were also reported in young rats that had been exposed to lead via maternal milk, but that at the time of testing had PbB levels below the detection limit (Cory-Slechta et al. 1992). 

The overall evidence from studies in animals supports the observations of lead neurobehavioral effects in humans. As pointed out by Cory-Slechta (1995), studies in animals have provided a direct measurement of the behavioral process per se, and have done so in the absence of the covariates (e.g., socioeconomic status, parental IQ) known to affect IQ scores in human studies. It is also worth noting that animal studies, in which the experimental design is carefully controlled, have shown that the timing of exposure is crucial, that different neurobehavioral outcomes are affected differently (different thresholds), and that some behavioral alterations last longer than others. 

Animal studies support he human evidence of neurobehavioral toxicity from prenatal exposure to low levels of lead. In an extensive review of the literature, Davis et al. (1990) discussed similarities between human effects and those in animals. The authors concluded that qualitatively "... the greatest similarities between human and animal effects involve cognitive and relatively complex behavioral processes such as learning." They further reported that quantitative relationships for PbB levels across species that cause developmental neurobehavioral effects are 10-15 pg/dL in children, <15 pg/dL in primates, and <20 pg/dL in rodents. 

Neurotoxicity. There is a very large database on the neurotoxic effects of lead. The most severe neurobehavioral effect of lead toxicity in adults is lead encephalopathy (Kehoe 1961a Kumar et al. 1987 Smith et al. 1978). Early symptoms, which may develop within weeks of initial exposure, include dullness, irritability, poor attention span, headache, muscular tremor, loss of memory, and hallucinations. These symptoms worsen, sometimes abruptly, to delirium, convulsions, paralysis, coma, and death. 

Pattillo RA Morehouse School of Medicine, Atlanta, GA Neurobehavioral effects of low-level exposure in human newborns ATSDR... 

Dietrich KN, Krafft KM, Bier M, et al. 1989. Neurobehavioral effects of foetal lead exposure The first year of life. In Smith M, Grant LD, Sors A, eds. Lead exposure and child development An international assessment. Lancaster, UK Kluwer Academic Publishers. 

Dietrich KN, Krafft KM, Shukla R, et al. 1987b. The neurobehavioral effects of early lead exposure. Monogr Am Assoc Ment Defic 8 71-95. 

Williamson AM, Teo RKC. 1986. Neurobehavioral effects of occupational exposure to lead. BrJInd Med 43 374-380. 

Friedman, Melissa A., and Bonnie E. Levin. "Neurobehavioral Effects of Harmful Algal Bloom (HAB) Toxins A Critical Review." Journal of the International Neuropsychological Society 11 (2005) 331-38. 

Spyker, J.M. and D.L. Avery. 1977. Neurobehavioral effects of prenatal exposure to the organophosphate diazinon in mice. Jour. Toxicol. Environ. Health 3 989-1002. 

Pyrethroid-induced neurobehavioral effects including clinical signs are known to be highly influenced by methodological changes in route, vehicle, dosing volume, species, and strain [19, 20]. The influence of the dose volume on the neurobehavioral effects after single oral administration was evaluated with... 

Ritchie, G.D., E.C.Kimmel, L.E.Bowen, J.E.Reboulet, and J.Rossi, III. 2001. Acute neurobehavioral effects in rats from exposure to HFC 134a or CFC 12. Neurotoxicology 22 233-248. 

Vehicles Can Mask the Effects of Active Ingredients. Particularly for clinical signs, attention should be paid to the fact that a number of vehicles (propylene glycol, for example) cause transient neurobehavioral effects that may mask similar short-lived (though not necessarily equally transient and reversible) effects of test materials. 

Franklin DJ, Brussaard CPD, Berges JA (2006) What is the role and nature of programmed cell death in phytoplankton ecology Eur J Phycol 41 1-14 Friedman MA, Levin BE (2005) Neurobehavioral effects of harmful algal bloom (HAB) toxins a critical review. J IntNeuropsychol Soc 11 331-338 Gross EM (2003) Allelopathy of aquatic autotrophs. Crit Rev Plant Sci 22 313-339... 

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