Workers exposed to lead show more cognitive problems later in lifeJanuary 12, 2009Cumulative, not current, lead is linked to subtle deficits in workers tested at age 55 and older WASHINGTON - Both the developing brain and the aging brain can suffer from lead exposure. For older people, a buildup of lead from earlier exposure may be enough to result in greater cognitive problems after age 55, according to a follow-up study of adults exposed to lead at work. A full report appears in the January issue of Neuropsychology, which is published by the American Psychological Association. From the Graduate School of Public Health and the School of Medicine at the University of Pittsburgh, the authors reported that cognitive problems were linked to cumulative exposure. The researchers followed up on the 1982 Lead Occupational Study, which assessed the cognitive abilities of 288 lead-exposed and 181 non-exposed male workers in eastern Pennsylvania. The lead-exposed workers came from three lead battery plants; the unexposed control workers made truck chassis at a nearby location. At both points in time, all the workers were given the Pittsburgh Occupational Exposures Test battery, which includes measures of five primary cognitive domains: psychomotor speed, spatial function, executive function, general intelligence, and learning and memory. In 1982, lead-exposed workers were found to have an average blood lead level of 40 micrograms per deciliter (ug/dL), well above normal. Pennsylvania workers found to have 25 ug/dL or more must be taken off the job. In 1982, the unexposed workers had an average blood level of 7.2, within normal limits. In 2004, the current study followed up with 83 of the original lead-exposed workers and 51 of the original non-exposed workers. Researchers measured current lead levels in their blood and cumulative lead levels through special X-rays of the tibia, or lower leg bone (bone is the final repository of circulating blood lead, where it has a half life of about 30 years). Researchers also re-administered the test battery to assess cognitive performance relative to both measures of lead. Among the lead-exposed workers, men with higher cumulative lead had significantly lower cognitive scores. The clearest inverse relationships - when one went up, the other went down - emerged between cumulative lead and spatial ability, learning and memory, and overall cognitive score. This linkage was more significant in the older lead-exposed men, of at least age 55. Their cognitive scores were significantly different from those of younger lead-exposed men even when the researchers controlled for current blood levels of lead. In other words, even when men no longer worked at the battery plants, their earlier prolonged exposure was enough to matter. The mild deficits, although not clinically significant, were consistent with other studies that show previous exposure to lead is, according to the authors, "particularly detrimental to the aging brain and that specific cognitive domains may be particularly vulnerable." Scientists have been investigating how lead damages the brain, especially the hippocampus and frontal cortex, seats of memory and learning. Lead exposure also puts people at greater risk for high blood pressure, which itself weakens cognition -- one possible pathway by which lead can cause problems. The men who built lead batteries were exposed to it in the air and through their skin. Other occupations, including semiconductor fabrication, ceramics, welding and soldering, and some construction work, also may expose workers. The authors wrote that, "Increased prevention measures in work environments will be necessary to reduce [lead exposure] to zero and decrease risk of cognitive decline." American Psychological Association |
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| Related Lead Exposure Current Events and Lead Exposure News Articles Prenatal exposure to flame-retardant compounds affects neurodevelopment of young children Prenatal exposure to ambient levels of flame retardant compounds called polybrominated diphenyl ethers (PBDEs) is associated with adverse neurodevelopmental effects in young children, according to researchers at the Columbia Center for Children's Environmental Health (CCCEH) at Columbia University's Mailman School of Public Health. Toxicants detected in Asian monkey hair may warn of environmental threats to people and wildlife Testing hair from Asian monkeys living close to people may provide early warnings of toxic threats to humans and wildlife, according to a study published online this week in the American Journal of Physical Anthropology. Heavy metal paradox could point toward new therapy for Lou Gehrig's disease New discoveries have been made about how an elevated level of lead, which is a neurotoxic heavy metal, can slow the progression of amyotrophic lateral sclerosis, or Lou Gehrig's disease - findings that could point the way to a new type of therapy. Childhood lead exposure causes permanent brain damage A study using functional magnetic resonance imaging (fMRI) to evaluate brain function revealed that adults who were exposed to lead as children incur permanent brain injury. The results were presented today at the annual meeting of the Radiological Society of North America (RSNA). Exposure to lead, tobacco smoke raises risk of ADHD Children exposed prenatally to tobacco smoke and during childhood to lead face a particularly high risk for ADHD, according to research done at Cincinnati Children's Hospital Medical Center. Children's blood lead levels linked to lower test scores Exposure to lead in early childhood significantly contributes to lower performances on end-of-grade (EOG) reading tests among minority and low-income children, according to researchers at Duke University and North Carolina Central University. Lead in bone associated with increased risk of death from cardiovascular disease in men Growing evidence shows that exposure to lead in the environment is associated with cardiovascular disease, including increased risk of hypertension. A child's IQ can be affected by mother's exposure to urban air pollutants A mother's exposure to urban air pollutants known as polycyclic aromatic hydrocarbons (PAHs) can adversely affect a child's intelligence quotient or IQ, a study reports. Children's IQ can be affected by mother's exposure to urban air pollutants Prenatal exposure to environmental pollutants known as polycyclic aromatic hydrocarbons (PAHs) can adversely affect a child's intelligence quotient or IQ, according to new research by the the Columbia Center for Children's Environmental Health (CCCEH) at the Mailman School of Public Health. Low Lead Levels In Children Can Affect Cardiovascular Responses To Stress Even low levels of lead found in the blood during early childhood can adversely affect how the child's cardiovascular system responds to stress and could possibly lead to hypertension later in life, according to a study from the State University of New York (SUNY) at Oswego. More Lead Exposure Current Events and Lead Exposure News Articles |
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