The scientists found that infants of low birth weight had higher levels of the phthalate di-n-butyl phthalate (DBP) in cord blood and higher levels of the DBP metabolite monobutyl phthalate (MBP) in meconium samples.

Meconium is the first stools passed by an infant containing material ingested during time in the womb. According to the scientists, it is often used to investigate in utero exposure to certain substances.

The study, published in the Journal of Pediatrics, also said that higher levels of di-2-ethylhexyl phthalate (DEHP) were associated with a shorter birth length. Similarly, levels of the metabolite MEHP were negatively associated with birth length.

The scientists, working at the Fudan University in Shanghai China, said: “This indicates that newborns, who are immature both developmentally and physiologically, may be at greatest risk for LBW after in utero exposure to DBP and DEHP.”

Members of the phthalate family of chemicals are found in wide variety of consumer products. Used as plasticizers they are often added to medical devices, plastic packaging, children’s toys and some personal care products.

DBP used in nail varnish

Although, DBP and DEHP are banned from use in personal care and cosmetics products in Europe, no such regulation exists in the US.

According to the Personal Care Products Council’s ingredients database, DBP was used extensively by nail polish manufacturers to avoid product chipping; but since it has been banned in some countries most manufacturers have stopped using it.

DEHP is no longer used in cosmetics and personal care products including nail polishes, according to the database.

Although this study suggests there maybe be a correlation between high levels of phthalates in newborns and low birth weight, the scientists say there are some limitations.

Primarily, there is no data on the sources of phthalates. The researchers state that no data on daily activity and consumer product use was available for the mothers during pregnancy, making it impossible to detect where the chemicals were from.

In addition, alcohol consumption and exposure to cigarette smoke are known contributors to low birth weights. The study did control for the mother’s exposure to alcohol and cigarette smoke in the home, it did not look at second hand exposure to cigarette smoke outside of the home.

This could have led to an overestimation of phthalate contribution, said the scientists.

Source: The Journal of Pediatrics
DOI: 10.1016/j.jpeds.2009.04.007
Phthalate levels and low birth weight: A nested case-control study of Chinese newborns
Yunhui Zhang, Ling Lin, Yang Cao, Bingheng Chen, Lixing Zheng, Ren-Shan Ge