MIAMI, Working in a consistently noisy environment such as a factory more than doubles the risk of serious heart problems, research suggests.

In the under-50s, the risk increases to fourfold, the study warns, and young male smokers are also particularly affected by noise.

The U.S. team studied more than 6,000 employees over a five-year period, dividing them into those who endured persistent loud noise at work for at least three months and those who did not.

They found those in noisy environments tended to weigh and smoke more than those who worked in quiet offices, reports the British Medical Journal.

Among workers under 50 the link with noise was particularly strong. They were between three and four times as likely to have angina or coronary artery disease or to have had a heart attack.

The authors say: ‘Loud noise day after day may be as strong an external stressor as sudden strong emotion or physical exertion, the effect of which is to prompt various chemical messengers to constrict blood flow through the coronary arteries.

‘This study suggests that excess noise exposure in the workplace is an important occupational health issue.’

June Davison of the British Heart Foundation said: ‘Some people find sustained noise very taxing and stressful and that could explain this link between noisy workplaces and an increased risk of heart disease.

‘If you’re stressed you are more likely to snack on unhealthy foods, smoke and miss out on your 30 minutes of physical activity a day – a sure-fire recipe for an unhealthy heart.

WASHINGTON,Some dinosaurs may have been at least 10 percent taller than previously thought, US paleontologists said in a study that found the creatures had large amounts of cartilage.

The dinosaurs had thick layers of cartilage in their joints that may have added more than a foot (30 centimeters) to their height, according to researchers at the University of Missouri (MU) and Ohio University, who said this may have changed their speed and posture.

"Our study of the limbs of modern-day relatives of dinosaurs shows that dinosaurs were significantly taller than original estimates," said study lead author Casey Holliday, an anatomy professor at the MU School of Medicine.

She explained that many dinosaurs' long bones, such as the femur or tibia, lack major articulations and have rounded ends with rough surfaces.

"This indicated that very thick cartilages formed these structures, and therefore the joints themselves, and would have added significant height to certain dinosaurs," Holliday added.

In contrast, mammal bones have small protrusions at their ends that help them connect with other bones at a joint. The bones are then linked with a very thin layer of cartilage.

The study, which was published in the Public Library of Science's journal PLoS-ONE, shed further light on how reptiles and mammals such as humans build their joints with different amounts of cartilage and bone.

The researchers compared articulations of ostriches and alligators -- the closest living relatives to dinosaurs -- to fossilized limbs of dinosaurs like Tyrannosaurus rex and Triceratops.

They found that alligators' and ostriches' limbs included six to 10 percent cartilage.

By applying a "cartilage correction factor," Holliday found that many theropod dinosaurs, such as Tyrannosaurus, were only modestly taller, while ornthischian and sauropod dinosaurs like Triceratops and Brachiosaurus, may have been 10 percent taller or more.

Brachiosaurus, which was previously thought to be 42 feet (13 meters) tall, may actually have been more than a foot taller with the additional joint cartilages, according to the researchers.

"This study is significant because it shows that bones can't always speak for themselves," said Lawrence Witmer, a professor of anatomy at the Ohio University College of Osteopathic Medicine.

"To understand how dinosaurs moved, we need to analyze the bones as they were inside their bodies, including their cartilage."