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Environmental Factor, February 2012

Extramural papers of the month

By Nancy Lamontagne

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New way to remove heavy metals from water

A system developed by NIEHS-supported engineers can cleanly and efficiently remove trace heavy metals from water. The low concentrations of these metals make them difficult to extract.

The engineers created a cyclic electrowinning/precipitation (CEP) system that increases the concentration of the heavy metals so that electrowinning can be used. Electrowinning employs an electrical current to transform positively charged metal ions into a stable solid state that can be easily separated from the water and removed.

In tests, the CEP system lowered levels of cadmium, copper, and nickel — both individually and as a mixture — to near or below maximum contaminant levels established by the U.S. Environmental Protection Agency. The system produced a very large reduction in the volume of the heavy metal contaminants, turning them into a solid metal deposited on particles that can be safely discarded or further processed to recover particular metals.

The technique is scalable and the researchers say it can be used to remove other heavy metals, such as lead, mercury, and tin.

CitationGrimshaw P, Calo JM, Hradil G. (http://www.ncbi.nlm.nih.gov/pubmed/22102792)  2011. Cyclic electrowinning/precipitation (CEP) system for the removal of heavy metal mixtures from aqueous solutions. Chem Eng J 175:103-109.

Perfluorinated compounds and immune response in children

Research funded by NIEHS has shown that elevated exposure to perfluorinated compounds was associated with reduced immune responses in children. Perfluorinated compounds are widely found in food packaging and textiles, but their impact on human health is not fully understood.

The prospective study followed children in the Faroe Islands, which are located in the North Atlantic about halfway between Scotland and Iceland. The investigators assessed prenatal exposure by measuring perfluorinated compounds in the mother’s serum during pregnancy, and later checked for the compounds in samples from the children at age five. They found that children with elevated exposure to perfluorinated compounds had lower antibody responses to childhood immunizations. The antibody response to childhood immunization reflects how well the immune system is functioning.

The researchers report that this study is one of the first to link childhood exposure to perfluorinated compounds with immune system deficiency. The results point to the importance of assessing the immunotoxic potential of these compounds, which are highly persistent and can contaminate drinking water, as well as food.

CitationGrandjean P, Anderson EW, Budtz-Jorgensen E, Nielsen F, Molbak K, Weihe P, Heilmann C. (http://www.ncbi.nlm.nih.gov/pubmed/22274686)  2012. Serum vaccine antibody concentrations in children exposed to perfluorinated compounds. JAMA 307(4 ):391-397.

Menthol lessens irritation from cigarette smoke

An NIEHS-supported study has shown that menthol, the cooling agent in peppermint, counteracts the irritating effects of cigarette smoke constituents. Menthol is added to most commercially sold cigarettes.

The researchers studied acrolein, acetic acid, and cyclohexanone, which are irritating components of cigarette smoke that vary widely in their chemical structure and biological properties. Using a mouse model of human sensory irritant sensitivity, the investigators found that the sensation of irritation was suppressed immediately in mice that inhaled the irritants and menthol at a concentration less than would be present in smoke from menthol cigarettes. When menthol was absent, the mice had more difficulty inhaling the irritants and exhibited more lung irritation. The experiments demonstrated that menthol’s counterirritant effects resulted from activation of the chemical receptor TRPM8.

By suppressing reactions such as coughing, menthol could increase the amount of smoke inhaled and thus promote addiction to nicotine. The 2009 Family Smoking Prevention and Tobacco Control Act banned flavored tobacco additives but exempted menthol while the U.S. Food and Drug Administration evaluated scientific data.

CitationWillis DN, Liu B, Ha MA, Jordt SE, Morris JB. (http://www.ncbi.nlm.nih.gov/pubmed/21903934)  2011. Menthol attenuates respiratory irritation responses to multiple cigarette smoke irritants. FASEB J 25(12):4434-4444. story (http://www.niehs.nih.gov/news/newsletter/2011/october/science-menthol/index.cfm)

Measuring cockroach allergen in the air

NIEHS grantees have developed a new sampling and analysis system for measuring exposure to indoor cockroach allergens. Indoor allergens are one factor that can increase risk for asthma development or exacerbation. 

Cockroach allergen exposure is usually assessed by collecting and analyzing settled dust, but this method might not provide accurate measurements of inhaled allergens. To measure airborne cockroach allergen, the researchers developed a technique that involves collecting a seven-day integrated total suspended particulate sample at approximately 10 to 15 liters per minute. They used the technique to collect airborne particle samples in 19 New York City apartments that were home to an asthmatic child who was allergic to cockroach allergen. The new method detected allergen in 87 and 93 percent of air samples in the bedroom and kitchen, respectively, where cockroach allergen was present in settled dust.

Sensitive and quantitative measurements of airborne cockroach allergen could reveal more about allergen aerodynamics in the homes of children with asthma.

CitationEsposito WA, Chew GL, Correa JC, Chillrud SN, Miller RL, Kinney PL. (http://www.ncbi.nlm.nih.gov/pubmed/21658130)  2011. Quantitative measurement of airborne cockroach allergen in New York City apartments. Indoor Air 21(6):512-520.

(Nancy D. Lamontagne is a science writer with MDB, Inc., a contractor for the NIEHS Division of Extramural Research and Training, Superfund Research Program, and Worker Education and Training Program.)



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