Exposure to low doses of a type of phthalate prior to puberty in mice can impact bone density later in life, an Australian study has found.
Phthalates, which have been used since the 1920 to make plastics more durable and flexible, came under fire several years ago amid concerns that they could be absorbed by people using items such as plasticware, with toxic effect.
The study follows on from previous work which showed an impact of low doses of these same chemicals on the reproductive organs of mice, which the authors say fuels concerns that low dose phthalate exposure impacts health.
“This is the first study demonstrating that prepubertal DBP (the type of phthalate studied) exposure causes long-term impacts outside the reproductive system, raising concern over potentially broad health implications,” the authors write.
“Dibutyl phthalate (DBP) is a chemical used for a variety of industrial purposes, from adhesives to plastics. It has been shown to have effects on the reproductive system, and its use is limited,” says Dr Ian Musgrave, a Senior Lecturer in the Faculty of Medicine, School of Medicine Sciences, within the Discipline of Pharmacology at the University of Adelaide, commenting on the findings.
“This latest paper shows that exposure to DBP may have effects on bone density when pre-pubertal mice are exposed to DBP for 17 days then followed to adulthood.
“Twelve measures of bone formation were assessed and three of these, including bone marrow volume and femur length, were significantly reduced in mice fed 100 and 500 mg DBP per kilogram of body weight per day.
“Bone mineral density was lower when mice were exposed to 10 mg DBP per kilogram of body weight per day, but not at higher exposures to DBP.
“This is an interesting result, and will require further investigation to determine the mechanism behind these changes and why mineral density is not affected by higher doses.
“However, in terms of human exposure the maximum human exposure limit is 0.01 mg per Kg body weight per day, a level that is 1000 times lower than the doses that produced reduce mineral density.
“In the 24th Australian diet study, only two of 48 surveyed foods had detectable DBP, and it would require eating over 10 Kg of the food every day to reach the levels of DBP that reduced bone mineral density in mice.”