Using IPM to Reduce Pyrethroid Pesticide Exposures in Dairy Workers

Principal Investigator: Michael Yost, PhD, MS
Chair and Professor, Environmental and Occupational Health Sciences
Director, Pacific Northwest Agricultural Safety and Health Center

NIOSH 2011-2016

This project partners with Washington State University to reduce pesticide use in dairy operations by introducing Integrated Pest Management (IPM)  practices in these workplaces. We are working with a network of participants to develop a robust and practical IPM program that provides evidence for cost-effective interventions that can reduce pesticide usage in these farm operations. University of Washington researchers will evaluate the potential for reducing pesticide use in dairy operations by conducting a targeted intervention to introduce more widespread use of Integrated Pest Management (IPM) practices in these workplaces.  Pyrethroid pesticides are widely used in agriculture and are applied on livestock in the form of sprays, dips, and tags to control flies and other insects, particularly in dairy operations. Pyrethroids also represent a potential workplace health issue in this region. Since 2001, pyrethroid-related illnesses documented by the Washington State Department of Health have quadrupled, suggesting that exposures to pyrethroid insecticides have been increasing both at home and in the workplace. For dairy and livestock operations, workers are at risk for exposures that come from contact with treated animals, treated surfaces, and proximity to application events. Given the multiple routes of exposure, biomonitoring using specific metabolites is an effective means of assessing worker exposures. In addition to the cost, storage, and handling issues associated with these chemicals, a future challenge to the industry is that insects are becoming pyrethroid-resistant, and alternative pest management strategies are needed. Alternative insect control strategies using IPM methods are available, which offer a potentially effective alternative that can reduce or eliminate costs and risks associated with pesticides.

Specific Aims: 
Aim 1. Estimate the prevalence of pesticide use and alternatives for pest management by surveying WA state dairies.

Aim 2. Work with cooperating dairy farms to assess the effectiveness and operating costs of current pest
management strategies by evaluating treatment practices and pest pressure.

Aim 3. Work in conjunction with WSU and with trade groups and individual owners to introduce existing
intervention strategies that improve pest management and improve handling methods. 

Aim 4. Assess potential pyrethroid exposures in a volunteer sample of workers by measuring metabolites in urine (inkind
contribution by WA-DOH).

Aim 5. Evaluate the effectiveness of the intervention strategies and work with WSU and farmers to develop
educational documents for wide dissemination to promote adoption of reduced risk pest management. 

Outcomes 
We developed the Dairy Pesticide Practices Survey along with our collaborators to understand current pest prevalence and pest management practices. Results showed that use of pyrethroid and pyrethrin insecticides was common throughout the state and that nonchemical options were becoming more accepted. After establishing a network of collaborating farms, we began to conduct a baseline assessment of the effectiveness and operating costs of their pest management strategies.

During the Summers of 2013 and 2014, PNASH researchers conducted IPM intervention trials to identify the effective pesticide management practices in collaboration with dairy partners. A calf-beddingtreatment method that inhibits larvae development demonstrated a positive correlation between calf-hutch bedding with lower pH and lower fly larvae counts. However, this intervention required more worker time to implement, making consistent compliance more difficult for the dairy. The second intervention used a larvicide, diflubenzuron, to prevent the development of fly larvae in manure. The larvicide was added to the adult cow feed and milk for calves for daily use during the peak fly season (June – September). The participating dairies had both young calves and adult cows. At one operation (three dairy locations), the operator observed that the use of the larvicide administered in the calves’ milk showed a marked reduction in fly populations in a large calf-hutch area compared to high fly populations in previous years. At the same dairy, the feedthrough product in the IPM program extended the time between permethrin applications on adult dairy cows (from once every 30 days to once every 40 days). 

The results of the study demonstrated that the IPM strategy implemented at participating dairies was an effective addition to the IPM fly control program. We found that feedthrough products integrated into dairies’ existing IPM fly control program reduced fly populations and, therefore, reduced the need for and the use of pyrethroid pesticides. This outcome then implies a reduced potential for worker exposure. Calf hutches benefited from the feed-through, as ventilation and manure/bedding removal is more limited for calves than for adult cows. Pour-on products, including those with active ingredients other than permethrin, need to be rotated across application dates to reduce the opportunity for the flies to develop resistance to one specific insecticide. The success of the feed-through addition indicates that IPM programs at other dairies could benefit from the use of feedthrough products.

General study results on worker pyrethroid exposure and prevention measures have been reported back to industry cooperators, including the following results: 1) Pyrethroid insecticides can be a potential exposure risk for dairy workers.They deposit and persist on metal surfaces such as chute railings and gates, and they may be present on cows and other surfaces; 2) All dairy workers need to be aware of the potential for exposure. Single-use disposable nitrile gloves around cows and barns would better protect hands from direct contact with the residues; 3) Standard hygiene practices would also contribute to minimizing these and other exposures at the dairies; 4) Additional beneficial protective practices include wearing clean work clothes each day, storing and washing dirty work clothes separately from the family laundry,and storing boots worn at work either at the dairy or outside of the home away from family shoes.

Partnerships
Washington State Dairy Federation
Washington State University
Washington State Department of Health

Products
Ferguson HJ, Galvin K, Vásquez VB, Yost M, O'Neal S. Survey of Pest Management Practices on Washington Dairy Farms. J Ext. 2015;53(2). pii: 2RIB8. PubMed PMID:29520118; PubMed Central PMCID: PMC5839334

Grinnell D. Overcoming Literacy and Language Barriers to Improve Safety Knowledge of Washington State Dairy Farm Workers. 2015 MS Thesis, University of Washington.

Fact Sheet – A Survey of Pest Management Practices on Washington State Dairy Farms

Fact Sheet – Feed-through Insecticide to Reduce Pyrethroid Use in Dairy Operations