Report calls for hog farm moratorium in Iowa

A new report on the rapid expansion of hog farms in Iowa calls for a moratorium on new barns and concludes that the state’s regulatory system is failing to protect the environment and public health for the sake of profit of the politically powerful livestock industry.

“A tipping point has been reached. Rural Iowans have every reason to be concerned,” said the report released by retired University of Iowa professors James Merchant and David Osterberg.

Study links household exposure to endotoxin with recurrent wheeze

A portrait of Peter Thorne of the Department of Occupational and Environmental Health at the University of Iowa College of Public Health.
Peter Thorne

Researchers at the University of Iowa recently reported the results of the largest study to date on the relationship between exposure to endotoxin and incidences of wheeze and asthma in children and adults. The study was a collaboration with researchers at the National Institute of Environmental Health Sciences and the National Center for Health Statistics.

Endotoxins are immune-modulating molecules found in the outer membrane of common bacteria that elicit inflammation in the airways of animals and humans.

According to research team leader Peter Thorne, professor and head of occupational and environmental health at the University of Iowa College of Public Health, the study showed that higher levels of endotoxin in dust samples were positively associated with an increased prevalence of active wheezing requiring medication and health care utilization.

“Everyone is exposed to some endotoxin,” Thorne says, “however, in this nationwide representative sample we showed that higher exposure would be expected to produce more severe wheezing in people both with and without allergy, producing more medication use and requiring more medical care.”

It was noteworthy that the relationship between endotoxin and wheezing did not exhibit a threshold, but showed a positive association over the entire range of values measured.

Thorne’s group tested endotoxin in bed and bedroom floor dust samples from almost 7,000 U.S. households using a novel approach that included unprecedented quality control measures. The participants were enrolled in the National Health and Nutritional Examination Survey (NHANES).

According to Thorne, endotoxin was found at higher concentrations in lower-income households and in households with carpet, children, pets, vermin, and smokers.

“The study shows the importance of improving the U.S. housing stock and educating people about the importance of controlling vermin, keeping a clean home. and eliminating indoor smoking.”

Results of the study were published in the December 2015 edition of the American Journal of Respiratory and Critical Care Medicine with an accompanying editorial. The full article is available here: http://www.atsjournals.org/doi/10.1164/rccm.201502-0251OC#.Vm8V5kZF0w8.

Researchers study air quality, heaters in livestock buildings

A current research project based in the Great Plains Center for Agricultural Health (GPCAH) is investigating methods to improve air quality in swine farrowing buildings1. The research team developed models to estimate room concentrations of multiple indoor contaminants [ammonia, dust, hydrogen sulfide, carbon monoxide, and carbon dioxide (CO2)] and conducted field monitoring to evaluate the effectiveness of using ventilation and engineering controls.

In both modeling and field work, the researchers found that CO2 concentrations exceeded recommended workplace limits for swine workers2 (1540 ppm) over the entire winter season and also exceeded one-half the Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL=5000 ppm), which is based on exposure to a single contaminant (unlike what exists in swine buildings). Sources of CO2 in livestock production include both animal respiration (exhaled breath) and combustion products from heaters.

Since controlling animal breathing is infeasible, the team evaluated whether the unvented heaters commonly used throughout the Midwest (e.g., LB White heaters) were a significant contributor to high CO2 levels measured in livestock buildings. In fall 2014, researchers installed new gas-fired heaters, the Effinity93 (60K BTU, approximately $500 more than equivalent LB White unit), in a test barn. The team measured concentrations throughout the following winter, comparing them to that of the previous winter with traditional unvented heaters.

To protect the unit from dust, fresh air intake to the combustion device was from outside the farrowing building, and combustion gases were exhausted from the unit to outside the building. The investigators identified that CO2 was reduced by 800 ppm with the new heaters.

Another 200 ppm difference in CO2 between seasons was attributed to colder outdoor temperature and larger in-room animal population in the winter with the older unvented heaters. Other vented gas-fired heaters are available, and the researchers recommend substituting unvented heaters with vented units that have stainless steel internal components, which should improve the lifespan of the heater when used in livestock environments containing ammonia.

1. See www.public-health.uiowa.edu/gpcah/center-projects/intervention-to-reduce-exposures-in-cafos/ for more details on this larger project.
2. Donham K, Haglind P, Peterson Y, et al. (1989) Environmental and health studies of farm workers in Swedish swine confinement buildings. Brit. J. Industr. Med. 46:31–37.

This story originally appeared in the September 2015 issue of Farm Families Alive & Well