Phthalates, the chemical agents that make some plastics flexible and help hold a perfume's scent, have come under considerable scrutiny recently. Some researchers have suggested that phthalates may have feminizing properties in humans, while others point to potential links between the compounds and abdominal obesity, among other concerns.

The American Chemistry Council, representing the plastic industry, vigorously defends the chemicals. The ACC says the chemicals have been used safely in consumer products for five decades.

What are phthalates?

Phthalates are chemicals used to make polyvinyl chloride — a type of plastic — flexible. They are also used to hold colour and scents in certain products. Sometimes referred to as plasticizers, phthalates can be found in a wide range of consumer products, including perfumes, nail polish, vinyl floors, detergents, lubricants, food packaging, soap, paint, shampoo, toys, air fresheners and plastic bags. They are also used to make certain medical devices including intravenous bags, blood bags and different kinds of tubing.

What does the latest research suggest about exposure to the chemical?

In October 2008, researchers at the University of Rochester's school of medicine found evidence that phthalates may have feminizing properties in humans.

Boys born to expectant mothers exposed to high levels of phthalates showed smaller penis sizes, incompletely descended testicles, and a shorter distance between the anus and base of the penis, compared with boys born to women exposed to low levels of the chemical.

Most boys had normal sex organs, and the differences were not serious, said Shanna Swan, director of the Center for Reproductive Epidemiology at the University of Rochester's school of medicine, who lead the study published in the journal Environmental Research.

The research was done on 106 boys from four U.S. states, a relatively small number, and the results need to be independently verified. It's not known if the exposure reduces fertility in adulthood.

In February 2008, a University of Washington study tested the urine of 163 infants and found that all the babies had at least one type of phthalate in their system while 81 per cent had at least seven different types. Among children who had recently had their hair shampooed or had lotion applied to their body, levels of phthalates were higher, the study said. The study cautioned, however, that the products themselves were not tested for phthalates. Researchers also noted there was no proof the chemicals found in the babies' urine were harmful. The study was published in the journal Pediatrics.

In March 2007, researchers at the University of Rochester Medical Center theorized that phthalates might be directly linked with abdominal obesity and insulin resistance in men. Drawing data from a U.S. national health survey, researchers found that men with the highest concentrations of phthalates in their urine had more belly fat and insulin resistance. The researchers cautioned that there was still much to study about the class of chemicals.

"Unfortunately, there's still a lot to learn about phthalates," said lead author Richard Stahlhut in a statement. "The more difficult issue is what combinations of common low-dose chemical exposures might be contributing to these problems."

The study was published in Environmental Health Perspectives.

How do I know whether a product contains phthalates?

Manufacturers are not obligated to include phthalates in the ingredients lists on children's products sold in Canada. Some manufacturers may list the chemicals on their packaging. Phthalates commonly used in products include:

• DBP (dibutyl phthalate).
• DINP (diisononyl phthalate).
• DEP (diethyl phthalate).
• DEHP (di 2-ethylhexl phthalate).
• DMP (dimethyl phthalate).
• BBP (benzyl butyl phthalate).
• DNOP (di-n-octyl phthalate).
• DIDP (Diisodecyl phthalate).

What is Health Canada's take on the chemicals?

On Jan. 18, 2011, Health Minister Leona Aglukkaq announced restrictions on the use of six phthalates in children's toys and some child-care products. As of June 10, 2011, the government will limit the allowable concentrations of DEHP, DBP and BBP to no more than 1,000 milligrams per kilogram in the soft vinyl of all children’s toys and child-care products. The rules will also restrict the permitted concentrations of DINP, DIDP and DNOP to no more than 1,000 mg/kg in the same products where children under four years old might put the soft vinyl in their mouths.

Are phthalates banned anywhere else?

California became the first U.S. state to ban products for children and babies containing more than residual quantities of phthalates. Since 2009, any children's product sold or distributed in California cannot contain more than one-tenth of one per cent of phthalates.

In August 2008, former U.S. President George W. Bush signed a bill partially banning phthalates. The bill outlawed the use of three types of phthalates in children's products. Three other phthalates have also been temporarily banned, as officials continue to study the effects of the chemicals. The bill doubles the Consumer Product Safety Commission's budget, to $136 million US by 2014, and gives it new authority to oversee product testing procedures and impose civil penalties on violators.

Meanwhile, the European Union has outlawed the use of DEHP, DBP and BBP in children's products. DINP, DNOP and DIDP are also banned in toys that children under the age of three might put in their mouths. Cosmetic manufacturers are also not permitted to use DEHP and DBP in the formulation of their products.