男性體內塑化劑濃度過高 將降低伴侶懷孕勝算

鄰苯二甲酸酯（塑化劑）是常用於消費性產品的化學物質，但美國國家衛生研究院和其他研究機構合作的最新研究發現，男性體內若有3種常見的鄰苯二甲酸酯濃度過高，妻子懷孕花的時間將比體內濃度低的男性要久。

塑化劑延遲受孕 效果相當於吸菸、肥胖

研究以2005年至2009年間密西根州和德州的501對夫妻為受試對象，測量他們尿液中雙酚A（BPA）和14種鄰苯二甲酸酯的濃度，並以受孕的勝算比（fecundability odds ratio）為統計工具，根據尿液中的化學物質濃度，計算受試夫妻的懷孕機率。機率少於1表示受孕花費時間較長，機率大於1表示花費時間較短。

研究發現，男性若體內鄰苯二甲酸單甲酯、單丁基鄰苯二甲酸和鄰苯二甲酸單芐基的濃度較高，妻子需要花較長的時間才能懷孕；夫妻體內的BPA濃度和懷孕速度則沒有關係。

結果顯示，BPA濃度無關受孕花費時間長短，但男性尿液中三種鄰苯二甲酸酯代謝物濃度較高者，伴侶受孕耗費時間拉長20%。研究主要作者、Eunice Kennedy Shriver兒童健康和人類發展研究院校內人口健康研究主任Germaine Buck Louis博士如此形容：「塑化劑延遲受孕的效果和吸菸或肥胖旗鼓相當。」

塑化劑讓塑膠不易碎 常見於多類家庭用品

鄰苯二甲酸酯又稱為塑化劑，是讓塑膠更有彈性不易碎的數種化學物質的總稱，含鄰苯二甲酸酯的商品有數百種，包括乙烯基地板、黏合劑、清潔劑、潤滑油、汽車塑膠零組件、金屬線塗層、塑膠衣和個人用品，如肥皂、洗髮精、髮膠和指甲油等；有些鄰苯二甲酸酯則是做溶劑使用。

塑化劑最常見於聚氯乙烯塑膠類製品，「鄰苯二甲酸酯聚氯乙烯」可用於製作塑膠包裝紙、塑膠水管、充氣玩具、血液貯存容器、醫療管材和部分兒童玩具；BPA則是用於製作某些特定形式的塑膠容器，如食物罐的保護襯裡等。

美國疾管局指出，人們吃下裝在塑膠容器中的食物和使用含有BPA或鄰苯二甲酸酯的物品，都會接觸到這些化學物質。不過美國化學理事會則堅持鄰苯二甲酸酯是安全的，「無數的科學小組審查過鄰苯二甲酸酯的安全性，結果幾乎都相同：一般的接觸情況下，商品中的鄰苯二甲酸酯並不會傷害人體。」



High Phthalate Levels in Males Delays Pregnancy in Partners



ROCKVILLE, Maryland, March 5, 2014 (ENS)




Women whose male partners have high concentrations of three common forms of phthalates, chemicals found in hundreds of consumer products, take longer to become pregnant than women in couples in which the male does not have high concentrations of the chemicals, finds new research by scientists at the National Institutes of Health and other institutions.

The researchers assessed the concentrations of phthalates and bisphenol A (BPA) in couples trying to achieve pregnancy.

Pregnancy took the most time to achieve in couples in which the males had high concentrations of monomethyl phthalate, mono-butyl phthalate, and monobenzyl phthalate. Neither male nor female exposure to BPA was associated with pregnancy rates.

Phthalates, often called plasticizers, are a group of chemicals used to make plastics more flexible and harder to break. Some phthalates are used as solvents for other materials. They are used in hundreds of products, such as vinyl flooring, adhesives, detergents, lubricating oils, automotive plastics, wire coatings, plastic clothes, and personal care products, such as soaps, shampoos, hair sprays, and nail polishes.

Phthalates are used widely in polyvinyl chloride plastics, which are used to make products such as plastic packaging film and sheets, garden hoses, inflatable toys, blood-storage containers, medical tubing, and some children’s toys.

BPA is used to make some types of plastic containers, in the protective lining of food cans, and other products.

People are exposed to phthalates and BPA by eating and drinking foods that have been in contact with containers and by exposure to products containing the compounds, according to the U.S. Centers for Disease Control and Prevention.

The study authors measured urine concentrations of BPA and 14 phthalate compounds in couples trying to achieve pregnancy. The researchers enrolled 501 couples from Michigan and Texas from 2005 to 2009.

The researchers calculated the probability that a couple would achieve pregnancy by using a statistical measure called the fecundability odds ratio (FOR). The measure estimates couples’ probability of pregnancy each cycle, based on their urinary concentration of the compounds. A ratio less than one suggests a longer time to pregnancy, while a ratio greater than one suggests a shorter time to pregnancy.

BPA concentrations were not associated with a longer time to pregnancy However, male urinary concentrations of the three metabolites of phthalates were associated with approximately a 20 percent increase in the time it took for the couples to achieve pregnancy:

“The delays in pregnancy we saw were comparable to those seen for cigarette smoking or with obesity,” said the study’s first author, Germaine Buck Louis, PhD, director of the Division of Intramural Population Health Research at NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development, or NICHD.

The American Chemistry Council maintains that phthalates are safe, saying, “Phthalates have been reviewed by numerous scientific panels and the conclusions have been essentially the same each time: that the phthalates used in commercial products do not pose a risk to human health at typical exposure levels.”