Sun, Nov 29, 2015 - Page 3 News List

Plasticizers affect IQ: study

By Chen Wei-han  /  Staff reporter

A study by National Health Research Institutes (NHRI) researchers suggests that children’s exposure to plasticizers is associated with reduced IQ and decreased cognitive development.

NHRI researcher Wang Shu-li (王淑麗) on Thursday announced the results of the 12-year study, saying that a 100 percent increase in children’s urinary phthalate metabolite levels lowers IQ scores by about 1 point.

Phthalates are a family of industrial chemicals that are widely used as plasticizers or softeners in a variety of commercial products, including food packaging, medical equipment, toys, furniture and cosmetics.

The team recruited 430 pregnant women in their third trimester from 2001 to 2002 and collected urine samples from mothers during pregnancy and later from the children, with a follow-up visit every three years up to 2012, Wang said.

The samples were analyzed for seven metabolite concentrations of widely used phthalates to examine the relationships between the phthalate metabolite levels and cognitive function, Wang said.

Significant inverse associations were found between the children’s IQ scores and their levels of metabolites of di(2-ethylhexyl) phthalate — the most common of the phthalates — as the mean IQ scores of the top 25 percent of children who had the highest phthalate metabolite levels were 5.69 points lower than those of the bottom 25 percent of children, who had lowest phthalates exposure, Wang said.

However, no significant association between maternal phthalate exposure and the children’s IQ scores was observed, she said.

Studies have suggested that low doses of phthalates could decrease the number of certain brain neurons, or disrupt the function of thyroid activity affecting neurocognitive development, she said, adding that phthalates are also considered endocrine disruptors that could boost estrogen and inhibit androgen.

The team found that children showed higher urinary phthalate metabolite concentrations than adults, suggesting that early-life phthalate exposure plays a significant role in cognitive development, she said.

The government in 2011 set the tolerable daily intake of DEHP at 50 micrograms per kilogram of body weight after phthalates used for industrial purposes were discovered in food products, before which 5 percent of children aged between two to eight were found to have consumed more than the allowable daily intake, but the percentages have diminished since food safety regulations were bolstered, she said.

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