Following a previous study linking higher maternal levels of two common chemicals with slower mental and motor development in preschoolers, a new study has found that this effect continues into school age.

The study involved 328 inner-city mothers and their children. The mothers' levels of prenatal urinary metabolites of di-n-butyl phthalate (DnBP), butylbenzyl phthalate (BBzP), di-isobutyl phthalate (DiBP), di-2-ethylhexyl phthalate and diethyl phthalate were measured in late pregnancy. IQ tests were given to the children at age 7.

Children's IQ scores were negatively associated with higher maternal phthalate levels. Among children of mothers with the highest versus lowest levels of DnBP and DiBP metabolite concentrations (the top 25% vs the bottom 25%), IQ was 6.7 and 7.6 points lower, respectively. There were similar associations with processing speed, perceptual reasoning and working memory; DiBP and verbal comprehension; BBzP and perceptual reasoning.

DnBP and DiBP are found in a wide variety of consumer products, from dryer sheets to vinyl fabrics to personal care products like lipstick, hairspray, and nail polish, even some soaps. Since 2009, several phthalates have been banned from children's toys and other childcare articles in the United States.

Although the results are correlational, and don't prove that phthalates are responsible, the researchers recommend that pregnant women avoid storing or microwaving food in plastic containers, and avoid scented cleaning and personal care products (phthalates hold scent). They are also advised not to use plastics labeled 3, 6, or 7.

Factors such as maternal IQ, maternal education, and quality of the home environment, were controlled for in the analysis. The range of phthalate metabolite levels measured in the mothers was not unusual.

[3841] Factor-Litvak, P., Insel B., Calafat A. M., Liu X., Perera F., Rauh V. A., et al.
(2014).  Persistent Associations between Maternal Prenatal Exposure to Phthalates on Child IQ at Age 7 Years.
PLoS ONE. 9(12), 

Older news items (pre-2010) brought over from the old website

Pollutants affect babies' brains

It appears that exposure to polychlorinated biphenyls (PCBs) in a mother's blood and breast milk can hinder the development of a baby's brain before and after birth. Although PCBs are now banned, these chemicals were once widely used in industry as coolants and lubricants and are still being leaked into the environment from old electrical equipment.

[591] Walkowiak, J., Wiener J. A., Fastabend A., Heinzow B., Krämer U., Schmidt E., et al.
(2001).  Environmental exposure to polychlorinated biphenyls and quality of the home environment: effects on psychodevelopment in early childhood.
Lancet. 358(9293), 1602 - 1607.

PCB-laden fish may affect adult verbal memory

The dangers of PCBs (once widely used as electrical insulators and lubricants and in paints and varnishes) have long been known, and assumed to apply chiefly to children and developing fetuses. A long-term study of those who eat the PCB-laden fish from Lake Michigan suggests for the first time that high levels of PCB may cause problems learning and remembering new verbal information in adults. In particular, those with high blood PCB levels had difficulties recalling a story told just 30 minutes earlier, and were less likely than their less-exposed peers to cluster words given orally into categories based on their meaning to boost recall.

Schantz, S.L., Gasior, D.M., Polverejan, E., McCaffrey, R.J., Sweeney, A.M., Humphrey, H.E.B. & Gardiner, J.C. 2001. Impairments of Memory and Learning in Older Adults Exposed to Polychlorinated Biphenyls via Consumption of Great Lakes Fish. Environmental Health Perspectives, 109 (6), 605.

How chronic exposure to solvents can impair the brain

Chronic occupational exposure to organic solvents, found in materials such as paints, printing and dry cleaning agents, has been linked to long-term cognitive impairment, but chronic solvent-induced encephalopathy (CSE) is still a controversial diagnosis. An imaging study of 10 CSE patients who had been exposed to solvents and had mild to severe cognitive impairment, 10 participants who had been exposed to solvents but had no CSE symptoms, and 11 participants who were not exposed to solvents and had no symptoms, has now found impairment in the frontal-striatal-thalamic (FST) circuitry of CSE patients. The disturbances are predictive of the clinical findings — impaired psychomotor speed and attention — and were also linked to exposure severity.

[989] van Dijk, F. J. H., Schene A. H., Heeten G D. J., Visser I., Lavini C., Booij J., et al.
(2008).  Cerebral impairment in chronic solvent-induced encephalopathy.
Annals of Neurology. 63(5), 572 - 580.

Chemical in clear plastics can impair learning

A rat study has found that low doses of the environmental contaminant bisphenol–A (BPA), widely used to make many plastics found in food storage containers (including feeding bottles for infants), inhibit estrogen–induction of synaptic connections in the hippocampus, suggesting implications for children's learning ability. Also, when the ability to make estrogen is impaired, as in old age, exposure to BPA could adversely affect hippocampal function and contribute to age–related neurodegenerative diseases such as Alzheimer's disease, in which hippocampal function is impaired. The doses were below the current U.S. Environmental Protection Agency reference daily limit for human exposure.

[740] MacLusky, N. J., Hajszan T., & Leranth C.
(2005).  The Environmental Estrogen Bisphenol A Inhibits Estradiol-Induced Hippocampal Synaptogenesis.
Environmental Health Perspectives. 113(6), 675 - 679.