Study links Parkinson's disease to industrial solvent

original article:

http://www.bbc.co.uk/news/health-15639440

snippets:

An international study has linked an industrial solvent to Parkinson's disease.

Researchers found a six-fold increase in the risk of developing Parkinson's in individuals exposed in the workplace to trichloroethylene (TCE).

Although many uses for TCE have been banned around the world, the chemical is still used as a degreasing agent.

The research was based on analysis of 99 pairs of twins selected from US data records.

Parkinson's can result in limb tremors, slowed movement and speech impairment, but the exact cause of the disease is still unknown, and there is no cure.

Research to date suggests a mix of genetic and environmental factors may be responsible. A link has previously been made with pesticide use.

'Significant association'

The researchers from institutes in the US, Canada, Germany and Argentina, wanted to examine the impact of solvent exposure - specifically six solvents including TCE.

They looked at 99 sets of twins, one twin with Parkinson's, the other without.

Because twins are genetically very similar or identical and often share certain lifestyle characteristics, twins were thought to provide a better control group, reducing the likelihood of spurious results.

The twins were interviewed to build up a work history and calculate likely exposure to solvents. They were also asked about hobbies.

The findings are presented as the first study to report a "significant association" between TCE exposure and Parkinson's and suggest exposure to the solvent was likely to result in a six-fold increase in the chances of developing the disease.

The study also adjudged exposure to two other solvents, perchloroethylene (PERC) and carbon tetrachloride (CCl4), "tended towards significant risk of developing the disease".

No statistical link was found with the other three solvents examined in the study - toluene, xylene and n-hexane.

"Our study confirms that common environmental contaminants may increase the risk of developing Parkinson's, which has considerable public health implications," said Dr Samuel Goldman of The Parkinson's Institute in Sunnyvale, California, who co-led the study published in the journal Annals of Neurology.

He added: "Our findings, as well as prior case reports, suggest a lag time of up to 40 years between TCE exposure and onset of Parkinson's, providing a critical window of opportunity to potentially slow the disease before clinical symptoms appear."
Water contaminant

TCE has been used in paints, glue, carpet cleaners, dry-cleaning solutions and as a degreaser. It has been banned in the food and pharmaceutical industries in most regions of the world since the 1970s, due to concerns over its toxicity.

In 1997, the US authorities banned its use as an anaesthetic, skin disinfectant, grain fumigant and coffee decaffeinating agent, but it is still used as a degreasing agent for metal parts.
Computer image of affected neurons in the brain of Parkinson's patients A computer image of affected neurons in the brain of Parkinson's patients

Groundwater contamination by TCE is widespread, with studies estimating up to 30% of US drinking water supplies are contaminated with TCE. In Europe, it was reclassified in 2001 as a "category 2" carcinogen, although it is still used in industrial applications.

PERC, like TCE, is used as a dry-cleaning agent and degreasing agent, and is found in many household products. CCl4's major historical use was in the manufacture of chlorofluorocarbons for use as refrigerants, but it has also been used a fumigant to kill insects in grain.

Commenting on the paper, Dr Michelle Gardner, Research Development Manager at Parkinson's UK, said: "This is the first study to show that the solvent TCE may be associated with an increased risk of developing Parkinson's.

"It is important to highlight that many of the previous uses of this solvent have been discontinued for safety reasons over 30 years ago and that safety and protection in work places where strong chemicals such as this solvent are used has greatly improved in recent years."

She also called for more research to confirm the link between TCE and other solvents with Parkinson's.

"Further larger-scale studies on populations with more defined exposures are needed to confirm the link," she said.

The Hidden Toll of Traffic Jams

original article:

http://online.wsj.com/article/SB10001424052970203733504577024000381790904.html?mod=WSJ_hp_MIDDLENexttoWhatsNewsThird

snippets:

Congested cities are fast becoming test tubes for scientists studying the impact of traffic fumes on the brain.

As roadways choke on traffic, researchers suspect that the tailpipe exhaust from cars and trucks—especially tiny carbon particles already implicated in heart disease, cancer and respiratory ailments—may also injure brain cells and synapses key to learning and memory.

New public-health studies and laboratory experiments suggest that, at every stage of life, traffic fumes exact a measurable toll on mental capacity, intelligence and emotional stability...

No one knows whether regular commuters breathing heavy traffic fumes suffer any lasting brain effect. Researchers have only studied the potential impact based on where people live and where air-pollution levels are highest. Even if there were any chronic cognitive effect on drivers, it could easily be too small to measure reliably or might be swamped by other health factors such as stress, diet or exercise that affect the brain, experts say.

Recent studies show that breathing street-level fumes for just 30 minutes can intensify electrical activity in brain regions responsible for behavior, personality and decision-making, changes that are suggestive of stress, scientists in the Netherlands recently discovered. Breathing normal city air with high levels of traffic exhaust for 90 days can change the way that genes turn on or off among the elderly; it can also leave a molecular mark on the genome of a newborn for life, separate research teams at Columbia University and Harvard University reported this year.

Children in areas affected by high levels of emissions, on average, scored more poorly on intelligence tests and were more prone to depression, anxiety and attention problems than children growing up in cleaner air, separate research teams in New York, Boston, Beijing, and Krakow, Poland, found. And older men and women long exposed to higher levels of traffic-related particles and ozone had memory and reasoning problems that effectively added five years to their mental age, other university researchers in Boston reported this year. The emissions may also heighten the risk of Alzheimer's disease and speed the effects of Parkinson's disease.

Reviewing birth records, Dr. Volk and her colleagues calculated that children born to mothers living within 1,000 feet of a major road or freeway in Los Angeles, San Francisco or Sacramento were twice as likely to have autism, independent of gender, ethnicity and education level, as well as maternal age, exposure to tobacco smoke or other factors. The findings were published this year in the journal Environmental Health Perspectives.

Exhaust fumes can extend farther from roadways than once thought. Traffic fumes from some major L.A. freeways reached up to 1.5 miles downwind—10 times farther than previously believed....

Scientists believe that simple steps to speed traffic are a factor in reducing some public-health problems. In New Jersey, premature births, a risk factor for cognitive delays, in areas around highway toll plazas dropped 10.8% after the introduction of E-ZPass, which eased traffic congestion and reduced exhaust fumes, according to reports published in scientific journals this year and in 2009...

Scientists are only beginning to understand the basic biology of car exhaust's toxic neural effects, especially from prenatal or lifetime exposures. "It is hard to disentangle all the things in auto exhaust and sort out the effects of traffic from all the other possibilities," says Dr. Currie, who studies the relationship between traffic and infant health.

Researchers in Los Angeles, the U.S.'s most congested city, are studying lab mice raised on air piped in from a nearby freeway. They discovered that the particles inhaled by the mice—each particle less than one-thousandth the width of a human hair—somehow affected the brain, causing inflammation and altering neurochemistry among neurons involved in learning and memory.

To study the effect of exhaust on expectant mothers, Frederica Perera at Columbia University's Center for Children's Environmental Health began in 1998 to equip hundreds of pregnant women with personal air monitors to measure the chemistry of the air they breathed. As the babies were born, Dr. Perera and colleagues tested some of the infants and discovered a distinctive biochemical mark in the DNA of about half of them, left by prenatal exposure to high levels of polycyclic aromatic hydrocarbons in exhaust.

By age 3, the children who were exposed prenatally to high exhaust levels were developing mental capacities fractionally more slowly. By age 5, their IQ scores averaged about four points lower on standard intelligence tests than those of less exposed children, the team reported in 2009. The differences, while small, were significant in terms of later educational development, the researchers said.

By age 7, the children were more likely to show symptoms of anxiety, depression and attention problems, the researchers reported this year in Environmental Health Perspectives.

"The mother's exposure—what she breathed into her lungs—could affect her child's later behavior," Dr. Perera says. "The placenta is not the perfect barrier we once thought."