RxPG News : Pollution

Drinking water DBPs safe for fetal survival

Thu, 07 Sep 2006 00:44:37 PST

( from http://www.rxpgnews.com ) Are disinfection by-products (DBPs) in drinking water harmful to an unborn fetus? According to a study in the November issue of the American Journal of Epidemiology (available online September 5), a team of researchers at the University of North Carolina School of Public Health headed by David A. Savitz, Ph.D., Director of the Center of Excellence in Epidemiology, Biostatistics, and Disease Prevention at MSSM, and formerly Chair of the Department of Epidemiology at the University of North Carolina at Chapel Hill, have determined that drinking water DBPs -- in the range commonly encountered in the US -- do not affect fetal survival. This finding is particularly important because previous research has suggested that exposure to elevated levels of drinking water DBPs might cause pregnancy loss.

The interaction of chlorine with organic material in raw water supplies produces chemical DBPs of health concern, including trihalomethanes (THMs) and haloacetic acids (HAAs). Several epidemiological studies have addressed potential reproductive toxicity of DBPs. The strongest support in ealier studies was noted for pregnancy loss, including stillbirth.

Researchers looked at three locations with varying DBP levels and evaluated 2,409 women in early pregnancy to assess tap water DBP concentrations, water use, other risk factors and pregnancy outcome. Tap water concentrations were measured in the distribution system on a weekly or biweekly basis. DBP concentration and ingested amount, bathing/showering and integrated exposure that included ingestion and bathing/showering were considered. Based on 258 pregnancy losses, the finding did not show an increased risk of pregnancy loss in relation to ingested amounts of DBPs.

"Decisions about treating drinking water nationwide rest in part on these health concerns, and our results provide assurance that there is no measurable adverse effect of disinfection by-products on risk of miscarriage. Given the need to control risk of infection through treatment and the huge expense involved in further reducing DBPs, this is good news for the water utility industry and their customers" said David A. Savitz, Ph.D., lead investigator and Director of the Center of Excellence in Epidemiology, Biostatistics, and Disease Prevention at MSSM.

Household cleaners and air fresheners emit toxic pollutants

Thu, 25 May 2006 12:32:37 PST

( from http://www.rxpgnews.com ) When used indoors under certain conditions, many common household cleaners and air fresheners emit toxic pollutants at levels that may lead to health risks, according to a new study by researchers at the University of California, Berkeley, and Lawrence Berkeley National Laboratory.

Exposure levels to some of the pollutants - and to the secondary pollutants formed when some of the products mix with ozone - may exceed regulatory guidelines when a large surface is cleaned in a small room or when the products are used regularly, resulting in chronic exposure, according to the study.

The study is the first to measure emissions and concentrations of primary and secondary toxic compounds produced by these products under typical indoor use conditions, and it examines the potential hazards of small-scale yet widespread utilization of an array of products designed for household use.

"We've focused a lot of effort in the last decades on controlling the big sources of air pollution and on the chemicals in consumer products that contribute to outdoor ozone formation. However, now we've learned that we need to pay attention to other aspects of pollution sources that are right under our nose," said William Nazaroff, a UC Berkeley professor of environmental engineering and the study's lead author.

To comply with its mandate to protect public health and welfare, for the past four decades the California Air Resources Board (ARB) has been developing and implementing regulatory programs to reduce air pollution in the state. These regulations also cover emissions of volatile organic compounds from consumer products used in homes and institutions.

Several years ago, when a handful of new studies raised the concern that consumer products may be contributing to indoor pollution levels in ways that were not fully understood, the ARB commissioned Nazaroff and his team to study the problem.

Four years in the making, the team's 330-page study and report, "Indoor Air Chemistry: Cleaning Agents, Ozone and Toxic Air Contaminants," was posted online by the ARB on Wednesday, May 10.

The ARB asked Nazaroff and his team to focus their work in two areas: an investigation of toxic air contaminants in household cleaning products and air fresheners, especially a class of chemicals known as ethylene-based glycol ethers; and an examination of the chemistry that occurs when such products are used indoors - in particular, products that contain a reactive group of chemicals called terpenes.

Ethylene-based glycol ethers are common, water-soluble solvents used in a variety of cleaning agents, latex paints and other products. They are classified as hazardous air pollutants under the U.S. Environmental Protection Agency's 1990 Clean Air Act Amendments and as toxic air contaminants by California's Air Resources Board. Their toxicity varies with their chemical structure.

Terpenes are a class of chemicals found in pine, lemon and orange oils that are used in many consumer products either as solvents or to provide a distinctive scent. Although terpenes themselves are not considered toxic, some recent studies have shown that they may react with ozone to produce a number of toxic compounds. (The primary constituent of smog, ozone enters the indoor environment from infiltration of outdoor air, but is also produced indoors by some office machines such as copiers or printers, and by some devices marketed as "air purifiers" that purposely emit ozone into the indoor environment.)

The research team's first task was to determine which household products contain terpenes and glycol ethers, and in what quantities. It compiled a list of the household cleaners and air fresheners available at any of five chain retail outlets in Northern California, then examined the labels and advertising claims (e.g. "pine-scented") for these products and reviewed available product data sheets. Based on this information, they selected the 21 products most likely to contain significant amounts of terpenes and ethylene-based glycol ethers: four air fresheners and 17 cleaning products, including at least one each of disinfectants, general-purpose degreasers, general-purpose cleaners, wood cleaners, furniture maintenance products, spot removers and multi-purpose solvents.

A complete chemical analysis of these 21 products revealed that:

Twelve contained terpenes and other ozone-reactive compounds at levels ranging from 0.2 to 26 percent by mass.

Six contained levels of ethylene-based glycol ethers of 0.8 to 9.6 percent by mass.

Among the four air fresheners studied, three contained substantial quantities of terpenes (9-14 percent by mass)

When the researchers tested the terpene-containing products in the presence of ozone, they found that reactions produced very small particles with properties like those found in smog and haze; other oxidation products; and formaldehyde, a respiratory irritant that is classified as a Group 1 carcinogen. (This designation by the International Agency for Cancer Research is reserved for substances for which there is sufficient evidence to conclude that they cause cancer in humans.) The amounts of terpenes that were converted into these pollutants was dependent on the amount of ozone present.

After completing their chemical analyses, the researchers ran a series of 18 experiments to determine the levels of exposure people might be subjected to when using the products in a confined space. The tests were conducted in a 230-square-foot room with ventilation at an ordinary level which provided approximately one air change every two hours. In some tests of terpene-containing products, ozone was introduced into the room at levels mimicking those that could occur in households or offices.

The products were used in various ways according to package directions: some at full-strength and others at various dilutions as recommended on their labels. In some tests, used cleaning supplies such as paper towels and sponges were left in the room. In others, supplies were promptly removed.

The tests produced various results - some reassuring, and some raising concerns.

The good news, the researchers reported, is that when people use the products under ordinary circumstances, their exposure to ethylene-based glycol ethers, formaldehyde and fine particles will normally not reach guideline values: that is, levels set by regulatory agencies as the maximum exposure levels believed to be safe. However, the authors pointed out, because formaldehyde is also released from other sources such as plywood and pressed wood products that are found in most buildings, any increase in formaldehyde emissions is undesirable.

In several realistic use scenarios, the tests showed that people could be exposed to potentially dangerous levels of toxic pollutants. The scenarios included:

Cleaning in a small, moderately ventilated bathroom. In calculations based on emissions from one of the glycol-ether containing products, the team found that a person who spends 15 minutes cleaning scale off of a shower stall could inhale three times the "acute one-hour exposure limit" for this compound set by the California Office of Environmental Health Hazard Assessment.

Air freshener and ozone in a child's bedroom. This scenario could occur when people use both air fresheners and ozone-generating devices simultaneously in a room. This could lead to exposures to formaldehyde that are 25 percent higher than California's guideline value. Because other sources of formaldehyde could also be present in the room, exposure to formaldehyde would probably be even higher, the report states.

Cleaning when outdoor ozone levels are high. This scenario simulates an apartment in Southern California on a day when the mid-afternoon outdoor ozone concentration is high. A person who stays in the kitchen for two hours after using a moderate amount of one of the terpene-containing products would breathe in about one quarter of the total daily guideline value for particulate matter.

Multi-house cleaning by a professional home cleaner. Under this scenario, a person who cleans four houses a day, five days per week, 50 weeks per year, would take in about 80 micrograms per day of formaldehyde, double the guideline value set by California's Proposition 65. In addition, the person's intake of fine particulate matter during the hours spent cleaning would exceed the average federal guideline level for an entire year. These quantities are in addition to the formaldehyde and particulate matter that the person would be exposed to from all other sources and activities during the year.

The take-home message from these studies, according to Nazaroff, is that everyone - but especially cleaning professionals - should be cautious about overuse of products with high levels of ethylene-based glycol ethers and terpenes. Rooms should be ventilated during and after cleaning, some products should be used in diluted solutions as opposed to full-strength, and cleaning supplies should be promptly removed from occupied spaces once cleaning is done. Also, people should avoid the use of ozone generators or ionizing air cleaners, especially in the same space where terpene-containing cleaning products or air fresheners are being used.

The report is an important milestone that highlights the need to investigate potential health effects of ultrafine particles produced in such reactions, said Bart Croes, chief of the ARB's Research Division.

"Dr. Nazaroff and his team have done a very thorough scientific assessment of the emissions from cleaning products and how they contribute to exposures of the users," Croes said. "Their results indicate that we need to look beyond the directly emitted compounds."

Common pollutants linked to fetal growth retardation

Thu, 17 Nov 2005 16:32:38 PST

( from http://www.rxpgnews.com ) Babies born to women exposed to high ozone levels during pregnancy are at heightened risk for being significantly underweight, according to researchers at the Keck School of Medicine of the University of Southern California.

Women who breathe air heavily polluted with ozone are at particular risk for having babies afflicted with intra uterine growth retardation-which means babies only fall within the 15th percentile of their expected size. The findings were published early online on the Web site of Environmental Health Perspectives, the journal of the National Institute for Environmental Health Sciences (NIEHS).

"These findings add further evidence that our ozone standards are not protecting the most vulnerable members of the population," says Frank D. Gilliland, M.D., Ph.D., professor of preventive medicine at the Keck School and the study's senior author.

Gilliland and his colleagues examined birth records from 3,901 children who were born in California between 1975 and 1987 and participated in the Children's Health Study. Researchers with the USC-led Children's Health Study have monitored levels of major pollutants in a dozen Southern California communities since 1993, while following the respiratory health of more than 6,000 students in those communities.

The researchers gathered data such as the children's gestational age and birth weight, as well as their mothers' zip code of residence at birth. Then they determined levels of ozone, carbon monoxide and other pollutants in the air in each zip code of residence during each mother's pregnancy. Researchers only considered full-term births for the study and controlled for factors such as mothers' smoking habits.

They found that each increase of 12 parts per billion (ppb) of average daily ozone levels over a mother's entire pregnancy was associated with a drop of 47.2 grams (g)-about a tenth of a pound-in a baby's birth weight. And the association was even stronger for ozone exposure over the second and third trimesters, Gilliland says.

In addition, for each 17 ppb increase in average daily ozone levels during a mother's third trimester of pregnancy, the risk of intra uterine growth retardation increased by 20 percent, the scientists report.

The effects were strongest when total average daily ozone exposure rose above 30 ppb. Ozone levels varied from less than 20 ppb in cleaner areas to above 40 ppb in more polluted areas of Southern California.

Carbon monoxide levels affected birth weight as well. They found that each increase of 1.4 parts per million of carbon monoxide concentration during the first trimester was associated with 21.7 g (about .05 pound) decrease in birth weight and a 20 percent increase in risk of intra uterine growth retardation.

Ozone, or O3, is a gas made up of three oxygen atoms. Although a natural layer of ozone in the stratosphere helps protect life on Earth from the sun's rays, ozone at ground level is harmful to health. It is created through interactions among tailpipe exhaust, gasoline vapors, industrial emissions, chemical solvents and natural sources and is worsened by sunlight and heat.

The study findings echo results from the few, smaller studies examining the relationship between ozone and birth weight. Animal studies support the role of O3 in reduced birth weight: in these models, pregnant rats were particularly vulnerable to lung inflammation from O3. Researchers suspect that inflammation from O3 may prompt the release of certain chemicals into the bloodstream, which may harm the placenta.

Carbon monoxide, meanwhile, is an odorless gas that primarily comes from vehicle exhaust. In high concentrations, the gas can harm healthy people; and in lower concentrations, it can hurt those with heart disease and can affect the nervous system.

The gas reduces hemoglobin's ability to carry oxygen where it is needed in the body; that may hurt the delivery of oxygen to a fetus. However, more research is needed to understand the roles of ozone and carbon monoxide in fetal development.

"Fetal growth and birth weight are strongly linked to morbidity and mortality during childhood and adulthood," Gilliland says, "so it's clear that air quality is important to everyone's healthy development."

17 percent of infants living near "stop and go" traffic suffer from wheezing

Sat, 23 Jul 2005 01:03:38 PST

( from http://www.rxpgnews.com ) University of Cincinnati (UC) environmental health researchers have found that 17 percent of infants living near "stop and go" traffic suffer from wheezing.

The study is the first of its kind to analyze the effects of "stop and go" bus and truck diesel traffic versus highway traffic on infant respiratory health.

Published in the August issue of the Journal of Allergy and Clinical Immunology, results of the four-year study suggest that the type of traffic and distance from it-- not just traffic volume--are associated with infant wheezing. Previous air pollution studies had not addressed these factors in infants.

"During the first year of life, an infant's lungs and immune system are still developing," said Patrick Ryan, lead author for the study in UC's Department of Environmental Health. "Overexposure to harmful particulates at such a young age may play a role in the development of allergic conditions."

The researchers tracked the respiratory health of 622 infants living near three traffic conditions: highway traffic, "stop and go" traffic, and areas unexposed to major roads or bus routes. A "stop and go" traffic area was defined as being within 100 meters (about 100 yards) of a bus or state route with a posted speed limit of 50 mph or less.

Research showed that infants living within 100 meters of "stop and go" traffic wheezed twice as often as those living within 400 meters (about 400 yards) of interstates, and more than three times as often as unexposed children.

African American infants living near "stop and go" traffic experienced the highest wheezing rate--25 percent.

"Our study illustrates that living within a football field's distance of 'stop and go' traffic puts infants at a higher risk for wheezing," said Ryan. "Traditional wisdom told us that highway traffic was to blame. We now know that's not necessarily the case."

Earlier research has shown that diesel exhaust particles (DEP), breathable particles able to absorb and transport proteins, aggravate rhinitis (hayfever) and asthma symptoms. According to the Ohio Environmental Council, 23 percent of Cincinnati residents live in areas of elevated DEP exposure, deemed "hot spots."

This year, U.S. Senator George Voinovich (R-OH) introduced the Diesel Emissions Reduction Act, an effort to improve air standards through diesel engine retrofits.

"Our findings reinforce the need to control diesel exhaust emissions," said epidemiologist Grace LeMasters, PhD, professor of environmental health and principal investigator of the study.

Biological mechanism might link particle pollution and heart attack risk

Wed, 08 Jun 2005 20:05:38 PST

( from http://www.rxpgnews.com ) Researchers from the Harvard School of Public Health and colleagues assessed the effect of high air pollution levels, specifically emissions from coal-burning power plants and diesel vehicles, on Boston-area adults with diabetes. Their study found that on days when air pollution levels were high, adults with diabetes were at higher risk for cardiovascular problems due to impairments in blood vessel function.

These results show a biological mechanism linking particulate pollution and impaired cardiovascular function. The findings appear in the June 7, 2005 issue of Circulation: Journal of the American Heart Association.
The study compared the effect of pollution on 270 greater Boston residents divided into two groups; one positively diagnosed with either type I or type II diabetes and the other comprised of non-diabetic individuals but with a family history of diabetes.

To assess blood vessel functioning, an ultrasound device was used to measure how well the participants' arteries were able to expand in response to increased blood flow through the arm.

Impaired blood vessel function is associated with an increased risk for atherosclerosis, heart attacks, stroke, other serious cardiovascular problems and death. On days with either high levels of sulfate particles from power plants or black carbon particles from automobile traffic, the arteries of the diabetics in the study were less able to expand in response to blood flow.

Specifically, on days when sulfate pollution was elevated the researchers found an 11 percent decrease in vascular reactivity among diabetic participants. On days when black carbon concentrations were elevated, diabetic study participants had a 13 percent decrease in vascular reactivity. In comparison, non-diabetics were not affected.

Beginning in the early 1990s researchers at the Harvard School of Public Health showed that particles in the air, predominantly from coal-burning power plants and traffic emissions, were associated with nearly 100,000 cardiovascular related deaths per year. What wasn't clear at that time was a demonstrated mechanism linking particle pollution to an increased risk for heart attacks or death.

Joel Schwartz, senior author of the study and professor of environmental epidemiology at the Harvard School of Public Health said, "This research highlights an important mechanism by which particles can increase the risk of heart attacks and deaths. If particles can impair the function of our arteries, it is understandable that this could increase the risk of death from heart disease. This puts greater emphasis on controlling air pollution sooner rather than later." Schwartz also noted that subjects without diabetes were not affected. "The number of diabetics in the US population is increasing rapidly, suggesting the impact of air pollution is likely to rise. This study shows that both coal-burning powerplants and diesel engines produce dangerous pollutants and should be controlled," said Schwartz. Because everyone did not respond the same, Schwartz highlighted the need for studies to identify other susceptible populations in addition to diabetics.

Tollbooth Ventilation System Effective in Protecting Workers from Traffic Air Pollution

Sat, 07 May 2005 15:44:38 PST

( from http://www.rxpgnews.com ) Although there is the potential for tollbooth workers at the Baltimore Harbor Tunnel to be exposed to high levels of cancer-causing air toxins emitted from the thousands of vehicles that pass under their nose, researchers from the Johns Hopkins Bloomberg School of Public Health found that the tollbooth ventilation system was effective in keeping air toxins out of the tollbooth and away from the workers. The researchers measured levels of volatile organic compounds (VOCs) and particle-bound polycyclic aromatic hydrocarbons (PAHs) inside and outside the tollbooth and found relatively high levels outdoors and relatively low levels indoors. The study is published in the May 1, 2005, issue of Environmental Science & Technology.

Tollbooth facilities represent a potential worst-case scenario for occupational exposure to mobile source-related air pollution, as these employees spend a majority of their shift within an arms length of thousands of vehicles emitting a wide range of toxic pollutants. Yet, little has been done to evaluate worker exposure and the protection afforded by the indoor environment, Amir Sapkota, PhD, lead author of the study and a post-doctoral fellow in the Bloomberg School of Public Healths Department of Environmental Health Sciences.

In June 2001, the researchers measured the concentration of air toxins at a tollbooth at the Baltimore Harbor Tunnel. They also examined traffic volume in addition to curbside pollutant concentrations and the concentrations inside the tollbooth. They compared air toxin levels during the three shifts worked by tollbooth employeesmorning (6 a.m.2 p.m.), afternoon (210 p.m.) and night (10 p.m.6 a.m.).

The researchers found that levels of 1,3-butadiene and benzene peaked with the morning and afternoon rush-hour traffic. In contrast, they found that the levels inside the tollbooth were relatively low and constant. They found, however, that some of the chlorinated VOCs used in dry cleaning, air deodorizers and cleaning products were present in higher concentrations inside the tollbooth than outdoors.

It is wonderful to discover that the tollbooth environment is doing what it is designed to doprotect workers from the hazardous environment in which they would otherwise be immersed. It is important to note, however, that not all tollbooth workers in this country, and especially in developing countries, are provided with this protection, said Timothy J. Buckley, PhD, MHS, senior author of the study and an associate professor in the Bloomberg School of Public Healths Department of Environmental Health Sciences.