Male reproductive disorders that are of interest from an environmental point of view include sexual dysfunction, infertility, cryptorchidism, hypospadias and testicular cancer.

Several reports suggest declining sperm counts and increase of these reproductive disorders in some areas during some time periods past 50 years. Except for testicular cancer this evidence is circumstantial and needs cautious interpretation. However, the male germ line is one of the most sensitive tissues to the damaging effects of ionizing radiation, radiant heat and a number of known toxicants.

So far occupational hazards are the best documented risk factors for impaired male reproductive function and include physical exposures (radiant heat, ionizing radiation, high frequency electromagnetic radiation), chemical exposures (some solvents as carbon disulfide and ethylene glycol ethers, some pesticides as dibromochloropropane, ethylendibromide and DDT/DDE, some heavy metals as inorganic lead and mercury) and work processes such as metal welding. Improved working conditions in affluent countries have dramatically decreased known hazardous workplace exposures, but millions of workers in less affluent countries are at risk from reproductive toxicants. New data show that environmental low-level exposure to biopersistent pollutants in the diet may pose a risk to people in all parts of the world.

For other noxicants the evidence is only suggestive and further evaluation is needed before conclusions can be drawn. Whether compounds as phthalates, bisphenol A and boron that are present in a large number of industrial and consumer products entails a risk remains to be established. The same applies to psychosocial stressors and use of mobile phones.

Finally, there are data indicating a particular vulnerability of the fetal testis to toxicants – for instance maternal tobacco smoking. Time has come where male reproductive toxicity should be addressed form entirely new angles including exposures very early in life.

Literatur:
Bonde JP., Male reproductive organs are at risk from environmental hazards, Department of Occupational and Environmental Medicine, Bispebjerg University Hospital, Copenhagen, Denmark, Asian J Androl. 2009 Dec 7.

The prevalence of allergic diseases such as asthma and pollinosis is steadily increasing and seems to be associated with modern lifestyle. Therefore, it has been hypothesized that high living standards and hygienic conditions reduce exposure to microbial components, and lead to an imbalance in the immune system, especially in the Thl and Th2 system, which increases the risk for the development of allergic diseases.

However, recent accumulated epidemiological evidences have demonstrated that air pollutants including diesel exhaust particulate (DEP) and NO2 are responsible for the increased prevalence of allergies. The effects of environmental chemicals have also been supported by the in vivo and in vitro studies. It is important to prevent allergy development in our life as early as possible (e.g., since our infancy). 

Reference: Nakamura H, Hitomi Y., Environmental factors in allergic diseases, Kanazawa University, Nippon Rinsho. 2009 Nov;67(11):2043-7.

Scientists have revealed how environmental irritants such as air pollution and cigarette smoke cause people to cough, in research published today in the American Journal of Respiratory and Critical Care Medicine. The authors of the study, from Imperial College London and the University of Hull, have identified the reaction inside the lungs that can trigger coughing when a person is exposed to particular irritants in the air. They suggest that their findings may ultimately lead to the development of new treatments for chronic coughing. 

Coughing is the most common reason for people visiting a family doctor. Treatment options are limited for people with chronic coughing; a recent study concluded that over-the-counter remedies are ineffective and there is increasing concern about the safety of these therapies in children. 

Today’s study indicates, for the first time, how coughing can be triggered when a person is exposed to certain irritants in the air. It shows that the irritants can switch on receptor proteins called TRPA1 on the surface of nerve endings in the lungs. This switches on sensory nerves, which then trigger a cough reflex. The researchers say coughing could potentially be treated by blocking TRPA1 receptors, to stop irritants in the air from setting off this chain reaction. They hope that this could ultimately help millions of people whose lives are affected by chronic coughing. 

Professor Maria Belvisi, corresponding author of the study from the National Heart and Lung Institute at Imperial College London, said: “For some people, chronic coughing can be annoying and uncomfortable, but for others it can be distressing and can have a severe impact on their quality of life. Many people say that certain things in the air can make them cough and we are very excited that we have shown, for the first time, exactly what is probably happening inside the lungs. Now that we think we have cracked the mechanism, we can start investigating whether we can stop people from coughing excessively by blocking the receptor protein that triggers it.” 

To reach their conclusions, the researchers first looked at sensory nerves from mice, guinea pigs and humans, and showed that the receptors on the sensory nerves were activated by a number of irritants, including a key compound in cigarette smoke (acrolein) and a chemical called cinnamaldehyde. The researchers then blocked the receptors and showed that these substances no longer activated the nerves. 

To establish whether activating the receptor causes coughing, the researchers looked at the effect of acrolein on guinea pigs, as they have a coughing reflex. The researchers assessed the guinea pigs’ coughing after inhaling acrolein. The compound caused coughing, and the higher the concentration, the more the guinea pigs coughed. The researchers then showed that blocking the receptor using a drug significantly reduced the guinea pigs’ coughing response to the compound.

Finally, researchers led by Professor Alyn Morice at the University of Hull looked at the effect of inhaling the chemical cinnamaldehyde in humans. Ten healthy, non-smoking volunteers inhaled the chemical, as well as control substances. The researchers measured their cough response on five occasions, 2-3 days apart. All of the volunteers coughed after inhaling the compound. 

Reference: Imperial College London, Research reveals exactly how coughing is triggered by environmental irritants, November 23, 2009

Surprisingly little is known about the effects of big-city air pollution on olfactory function and even less about its effects on the intranasal trigeminal system, which elicits sensations like burning, stinging, pungent, or fresh and contributes to the overall chemosensory experience. 

Using the Sniffin’ Sticks olfactory test battery and an established test for intranasal trigeminal perception, we compared the olfactory performance and trigeminal sensitivity of residents of Mexico City, a region with high air pollution, with the performance of a control population from the Mexican state of Tlaxcala, a geographically comparable but less polluted region. 

We compared the ability of 30 young adults from each location to detect a rose-like odor (2-phenyl ethanol), to discriminate between different odorants, and to identify several other common odorants. The control subjects from Tlaxcala detected 2-phenyl ethanol at significantly lower concentrations than the Mexico City subjects, they could discriminate between odorants significantly better, and they performed significantly better in the test of trigeminal sensitivity. 

We conclude that Mexico City air pollution impairs olfactory function and intranasal trigeminal sensitivity, even in otherwise healthy young adults. 

Reference:    Guarneros M, Hummel T, Martínez-Gómez M, Hudson R., Mexico City Air Pollution Adversely Affects Olfactory Function and Intranasal Trigeminal Sensitivity, Chem Senses. 2009 Oct 9.

Plumes of harmful air pollutants can be transported across oceans and continents — from Asia to the United States and from the United States to Europe — and have a negative impact on air quality far from their original sources, says a new report by the National Research Council.  Although degraded air quality is nearly always dominated by local emissions, the influence of non-domestic pollution sources may grow as emissions from developing countries increase and become relatively more important as a result of tightening environmental protection standards in industrialized countries.  

“Air pollution does not recognize national borders; the atmosphere connects distant regions of our planet,” said Charles Kolb, chair of the committee that wrote the report and president and chief executive officer of Aerodyne Research Inc.  “Emissions within any one country can affect human and ecosystem health in countries far downwind.  While it is difficult to quantify these influences, in some cases the impacts are significant from regulatory and public health perspectives.” 

The report examines four types of air pollutants: ozone; particulate matter such as dust, sulfates, or soot; mercury; and persistent organic pollutants such as DDT.  The committee found evidence, including satellite observations, that these four types of pollutants can be transported aloft across the Northern Hemisphere, delivering significant concentrations to downwind continents.  Ultimately, most pollutants’ impacts depend on how they filter down to the surface.  

Current limitations in modeling and observational capabilities make it difficult to determine how global sources of pollution affect air quality and ecosystems in downwind locations and distinguish the domestic and foreign components of observed pollutants.  Yet, some pollutant plumes observed in the U.S. can be attributed unambiguously to sources in Asia based on meteorological and chemical analyses, the committee said.  For example, one study found that a polluted airmass detected at Mt. Bachelor Observatory in central Oregon took approximately eight days to travel from East Asia.  

The health impacts of long-range transport vary by pollutant.  For ozone and particulate matter — which cause respiratory problems and other health effects — the main concern is direct inhalation.  While the amount of ozone and particulate matter transported on international scales is generally quite small compared with domestic sources, neither of these pollutants has a known “threshold,” or concentration below which exposure poses no risk for health impacts.  Therefore, even small incremental increases in atmospheric concentrations can have negative impacts, the committee said.  For instance, modeling studies have estimated that about 500 premature cardiopulmonary deaths could be avoided annually in North America by reducing ozone precursor emissions by 20 percent in the other major industrial regions of the Northern Hemisphere. 

For mercury and persistent organic pollutants, the main health concern is that their transport and deposition leads to gradual accumulation on land and in watersheds, creating an increase in human exposure via the food chain.  For example, people may consume mercury by eating fish.  There is also concern about eventual re-release of “legacy” emissions that have been stored in soils, forests, snowpacks, and other environmental reservoirs. 

In addition, the committee said that projected climate change will lead to a warmer climate and shifts in atmospheric circulation, likely affecting the patterns of emission, transport, transformation, and deposition for all types of pollution.  However, predicting the net impacts of the potential changes is extremely difficult with present knowledge. 

In the coming decades, man-made emissions are expected to rise in East Asia, the report says.  These increases could potentially be mitigated by increasingly stringent pollution control efforts and international cooperation in developing and deploying pollution control technology. 

To enhance understanding of long-range transport of pollution and its impacts, the committee recommended a variety of research initiatives, such as advancing “fingerprinting” techniques to better identify source-specific pollutant characteristics, and examining how emissions from ships and aircraft affect atmospheric composition and complicate the detection of pollution from land-based sources.  The committee emphasized developing an integrated “pollution source-attribution” system that improves capabilities in emissions measurements and estimates; atmospheric chemical and meteorological modeling; long-term, ground-based observations; satellite remote sensing; and process-focused field studies.  

Moreover, the committee stressed that the United States, as both a source and receptor of long-range pollution, has an interest in remaining actively engaged in air pollutants that travel abroad, including support of more extensive international cooperation in research, assessment, and emissions control efforts. 

The report was sponsored by the U.S. Environmental Protection Agency, National Oceanic and Atmospheric Administration, NASA, and National Science Foundation.  The National Academy of Sciences, National Academy of Engineering, Institute of Medicine, and National Research Council make up the National Academies.  They are independent, nonprofit institutions that provide science, technology, and health policy advice under an 1863 congressional charter.  Committee members, who serve pro bono as volunteers, are chosen by the Academies for each study based on their expertise and experience and must satisfy the Academies’ conflict-of-interest standards.  The resulting consensus reports undergo external peer review before completion.  For more information, visit National Academies  A committee roster follows. 

Reference: National Academy of Sciences, Air Pollutants From Abroad a Growing Concern, Says New Report, Washington, September 29. 2009