Fertilizer Use and Self-Reported Respiratory and Dermal Symptoms Among Tree Planters

Abstract

In British Columbia, some tree planting operations require workers to fertilize planted seedlings with polymer-coated nitrogen, phosphorus, and potassium (NPK) fertilizers. This study examined respiratory and dermal health associated with fertilizer exposure among tree planters. We interviewed 223 tree planters using an adapted version of the American Thoracic Society questionnaire supplemented with questions on dermal health. Subjects were grouped by categories of increasing duration of exposure, with workers who had not worked with fertilizer as a reference group. The relationship between exposure and reported work-related symptoms was analyzed using logistic regression, adjusting for age, cumulative tobacco cigarettes smoked, marijuana smoking status, sex, and exposure to abrasive spruce needles. An elevated odds ratio was seen for work-related cough, phlegm, nasal symptoms, nosebleed, and skin rash in the highest exposure group (>37 days of fertilizer use in the past 2 years) but was significant only for phlegm (odds ratio = 3.59, 95% confidence interval = 1.10–11.70). Trends of increasing odds ratios with increasing exposure were seen for cough, phlegm, nasal symptoms, and skin rash. The results suggest a weak association between respiratory and dermal irritation and work with fertilizer. Results highlight the need for further exposure monitoring within the tree planting industry, and larger studies to investigate the relationship between work with fertilizer and respiratory and dermal health symptoms. [Supplementary materials are available for this article. Go to the publisher's online edition of the Journal of Occupational and Environmental Hygiene  for the following free supplemental resource: a PDF file containing a respiratory and dermal health questionnaire.]

Keywords:

• dermal irritation forestry
• occupational exposure
• questionnaire
• respiratory irritation

ACKNOWLEDGMENTS

The authors wish to thank the silvicultural contracting companies who participated in the study and helped field staff to navigate the rugged tree planting work sites. We would also like to thank Adrian Hingston, Craig Evans, Eric Phillips, Christina Prucker, and Birgit Jatzko, who all assisted with field research. We are very grateful to the tree planters who took the time to complete the interview. Amy Shafrir provided useful suggestions on the manuscript. This study was funded by WorkSafeBC, the Western Silvicultural Contractor's Association, Island Timberlands LP, and by Natural Resources Canada under the NRCan/FP Innovations-Feric contribution Agreement. M. Koehoorn was supported in part by a Michael Smith Foundation for Health Research Scholar Award.