Veterinary Pharmaceutical Analysis of Irrigation Water in Southern Alberta

Executive Summary:
More than 65% of Canada's irrigation occurs in southern Alberta's irrigation districts. The associated
irrigation conveyance network supplies water for crops and livestock production, as well as for rural
communities and many rural homes. Irrigation water provides wildlife habitat and recreational activities
such as fishing, boating, and camping on irrigation reservoirs. Good quality irrigation water is important
for all these uses. The quality of irrigation water in Alberta has been previously monitored by several
researchers, but differences in study design and objectives made the data difficult to compare. A 10-year
study (2006 to 2007 and 2011 to 2018) was conducted by the Government of Alberta, Agriculture and
Agri-Food Canada, and Alberta Irrigation Projects Association (now Alberta Irrigation Districts
Association) to assess the quality of irrigation water within Alberta's irrigation districts using a long-term,
consistent approach. This report is one of a series of reports based on data collected from the 10-year
Irrigation District Water Quality project. The focus of this report is to examine the presence of veterinary
pharmaceuticals and synthetic hormone residue in irrigation water of southern Alberta.
Veterinary pharmaceuticals and synthetic growth hormones are routinely administered to livestock in commercial feeding operations to treat and prevent diseases, improve health, and promote growth by increasing feed efficiency. Veterinary pharmaceuticals prevent economic loss and help ensure a safe and secure food supply for the human population. However, due to partial metabolism of administered pharmaceuticals and hormones, unmetabolized compounds and metabolites are excreted in feces and urine of treated animals. This results in possible transport of these compounds into irrigation water from runoff of these operations, manure-amended lands or direct livestock access, and may be a concern for downstream water users.
Fifteen Irrigation District Water Quality project sites were selected for the detection and quantification of
veterinary pharmaceuticals in 2013, and 24 sites were selected in 2014 and 2015. These sites were
located in eight irrigation districts and were selected based on elevated Escherichia coli (E.coli)
concentrations which when compared to other sites, may indicate a livestock influence. Six veterinary
pharmaceuticals were selected for detection and quantification in 2013, including chlortetracycline,
tylosin, sulfamethazine monensin, lincomycin, and erythromycin. In 2014 and 2015, tetracycline was
added to the pharmaceutical suite. Twenty-nine Irrigation District Water Quality project sites were
selected for the detection of livestock synthetic growth hormone residue in 2016 through 2018. These
sites were located in the same eight irrigation districts as the veterinary pharmaceutical analysis. Two
synthetic growth hormones (trenbolone acetate and melengestrol acetate) and three metabolites of
trenbolone acetate (17α-trenbolone, 17β-trenbolone, and trendione) were selected for detection and
quantification.
Six of the seven veterinary pharmaceuticals were detected; lincomycin was not detected. Some compounds such as tetracycline and chlortetracycline had detection frequencies often greater than 95%. Others, such as tylosin and erythromycin, had variable detection frequencies with some as high as 97% for one year and as low as 1% in another year. Confounding factors such as differences in weather (i.e., temperature or amount of precipitation), mobility of compounds in soils, or variations in usage or administered dose of compounds
may help to explain this annual variability but this data was not collected within the scope of this study.
The most obvious patterns in the presence of these compounds in irrigation water were seen among the seven veterinary pharmaceutical compounds themselves, with some being more frequently detected than others and at higher concentrations than others. There were no visual patterns in detection frequencies or concentrations among the districts. There were also no observable differences between site types within districts, indicating that concentrations of veterinary pharmaceuticals may not be cumulative as water moves downstream.
Although detection frequencies of some veterinary pharmaceutical compounds were high, the concentrations at
which compounds were detected was generally very low and well below the levels of toxicity of non-target
species. These low concentrations also indicate low risk of contribution to antimicrobial resistance.
No synthetic hormone residues were detected in any of the samples analyzed. This was not unexpected
as concentrations of synthetic hormones in manure are usually low and typically synthetic hormones have
rapid dissipation rates in the environment.