Correlation between Nitrate and Nitrosatable Agrichemicals in Nebraska Groundwater and the Risk of Adverse Birth Outcomes

Ashley Thyes Author

04/04/2021 Added

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[00:00:00.330]Hi everyone.
[00:00:01.080]My name is Ashley Thyes and I'm a student and researcher with the birth outcomes
[00:00:04.170]and water research project, which is led by Dr. Martha Rhoades.
[00:00:08.430]This past year,
[00:00:09.330]I have been researching the correlation between nitrate and nature,
[00:00:12.240]state of agrichemicals in Nebraska groundwater and the risk of adverse birth
[00:00:17.220]outcomes to begin with.
[00:00:18.990]I'll give you a little bit of an introduction or background, then go on to
[00:00:22.350]the methods I used and the results I got,
[00:00:24.480]and one with a conclusion and some discussion.
[00:00:29.790]So.
[00:00:30.390]According to Nebraska's 2016 vital statistics report,
[00:00:33.780]Nebraska's rate of birth effects,
[00:00:35.670]which is 6% is normally higher than the national rate of 3%,
[00:00:39.270]which is obviously something we do not like to see.
[00:00:42.600]Nebraska is also located in the corn belt and agricultural practices often use
[00:00:47.040]atrazine and nitrogen based fertilizers.
[00:00:48.510]Atrazine and Nitrate have been detected in groundwater and can be
[00:00:52.920]present in drinking water.
[00:00:54.630]This is not good because when atrazine and nitrate combined under acidic
[00:00:59.040]conditions, such as the human stomach,
[00:01:01.350]it can combine to form a nitrosamine called n nitrosoatrazine or NNAT
[00:01:06.060]which is what I'll be calling it for the rest of this presentation.
[00:01:10.560]Exposure in nitrosamines may also be correlated with neural tube defects,
[00:01:14.730]cleft palate, neonatal death, and stillbirth in rodents.
[00:01:18.450]NNAT may cause chromosomal abnormalities in human lymphocytes in vitro
[00:01:23.490]at low concentrations,
[00:01:25.470]Exploratory research showed a positive correlation between the birth defect
[00:01:28.800]rates and the percent of Wells containing nitrate and at least one nature state
[00:01:32.580]of a compound.
[00:01:33.720]So the purpose of my research project was to identify the relationship between
[00:01:37.710]exposures of nitrate and nitrosatable agrichemicals in drinking water,
[00:01:42.240]birth defects rates, and
[00:01:44.550]Fetal death rates, which I did.
[00:01:46.350]By utilizing new data gathered about fetal death rates in each County.
[00:01:50.850]I also wanted to better understand associations between exposure to nitrate and
[00:01:55.320]nitrosatable agrichemicals and the risk of adverse birth outcomes
[00:02:00.150]To do this,
[00:02:00.690]I started off by adding to an existing data set that contained some
[00:02:04.800]agrichemical information.
[00:02:06.390]This data set included information about the number of wells that tested
[00:02:10.440]positive for each agrichemical and the total wells that were tested for the
[00:02:14.270]agrichemical. And we had this data each of Nebraska's 93 counties.
[00:02:19.800]And from this information we could calculate the percent of those positive for
[00:02:23.880]each ever chemical by dividing
[00:02:25.860]the number of was tested positive by the total number of laws that were tested.
[00:02:31.230]I created
[00:02:32.040]15 New variables to add to this dataset and I combined various
[00:02:36.390]combinations of nitrate concentrations greater than zero, nitrate
[00:02:40.340]concentrations greater than two, atrazine,
[00:02:43.140]DEA, and DIA to see if any agrichemicals were present in the water samples
[00:02:47.700]multiple times.
[00:02:51.380]So after a little bit of data manipulation,
[00:02:53.630]I ran correlations of all the variables against the following variables,
[00:02:57.230]2010 to 2014 birth weight, less than 1,500 grams birth weight,
[00:03:02.170]less than 2,500 grams fetal death rate, infant death rate, neonatal death rate,
[00:03:07.180]perinatal death rate, 2005 to2014,
[00:03:10.270]all birth defects, and 2005 to 2014, national birth defect prevention study,
[00:03:15.550]or NBDPS birth defects.
[00:03:18.750]The bcrth defect rate and fetal death rate for each County were obtained from the
[00:03:23.340]Nebraska department of health and human services DHHS.
[00:03:28.440]So like I mentioned before,
[00:03:29.940]I had to do a little data manipulation before I could run these correlations.
[00:03:33.630]So one of these
[00:03:35.400]data manipulations I did was restructuring well data so that each well was
[00:03:39.540]represented in the data analysis only once. To do this,
[00:03:42.780]I took advantage of Clearinghouse numbers.
[00:03:45.300]So when we did our queries from the
[00:03:49.470]quality assessed contaminant database from Nebraska ground water,
[00:03:54.660]um, each well is given a clearing house number. So no matter how,
[00:03:59.130]how many different agrichemicals or how many different times the well is tested,
[00:04:02.670]it always has the same clearinghouse number.
[00:04:04.860]So I use the cleaninghouse numbers to, um,
[00:04:07.620]make sure that each one was only represented in the data analysis once.
[00:04:11.850]So I ran these correlations using the Kendall Tau correlation,
[00:04:16.350]coefficient tests,
[00:04:17.490]and I've used this test because not all variables are normally distributed.
[00:04:22.770]And I did all this analysis in SPSS. From our results,
[00:04:27.630]I got this nice little table that I put up top and all
[00:04:32.610]the agrichemicals had significant positive correlation
[00:04:37.320]except for five. So we can see from this table that three
[00:04:42.570]agrichemicals that have significant correlations with on less than
[00:04:46.860]1,500 grams birth weight,
[00:04:49.380]seven agrochemicals have significant correlations with less than 2,500 grams.
[00:04:54.540]birth weight,
[00:04:56.010]three agrochemicals are significant correlations with fetal death.
[00:05:00.060]One agrichemical has a significant correlation with infant death to agrichemicals
[00:05:04.500]have significant correlation with neonatal death and 17. Um,
[00:05:08.880]agrichemicals have significant correlations with all birth defect. Three,
[00:05:13.290]agrichemicals have significant correlations with NBDPS birth defects.
[00:05:18.330]There were zero agrichemicals that had significant correlation with perinatal
[00:05:21.570]death rate, so I just eliminated that from the results (display)
[00:05:25.740]So we can look at these right results and the correlations to understand the
[00:05:29.820]impacts of drinking water containing nitrate,
[00:05:32.190]and nitrosatable agrichemicals in adverse outcomes. So just fetal death,
[00:05:36.660]perinatal death, infant death, neonatal death, and the birth defect rate.
[00:05:41.550]While we cannot infer causation because of the correlation,
[00:05:44.340]we can use these results in the knowledge agrichemicals have significant
[00:05:47.370]correlations to generate future hypotheses.
[00:05:51.810]This project also allows us to better understand associations between exposures
[00:05:55.860]to nitrate and nitrostable agrichemicals and the risk of adverse birth outcomes.
[00:06:00.920]Previous literature and research had mostly looked at single compounds.
[00:06:03.890]while this research looked at mixtures of compounds.
[00:06:08.420]Another result I found was that there were 97 pairs significantly
[00:06:12.530]correlated chemicals,
[00:06:14.300]which is a limitation of a study because contaminants
[00:06:19.160]could be surrogates for one another. But, um,
[00:06:22.730]we do not know if the agrichemicals are casual in
[00:06:27.620]an increased risk of birth defect. So, um,
[00:06:31.730]we do not know if these are chemicals are confounders for sure.
[00:06:35.570]The only thing we can do because of this is compare areas where surrogates
[00:06:40.460]are present to areas where the surrogates are not present and see if
[00:06:45.020]agrichemicals have an equal effect on the outcome. Finally,
[00:06:48.560]I would like to thank several people for their help with this project.
[00:06:52.190]It would not have been possible without them, Dr. Cheryl Beseler for
[00:06:56.480]her statistics knowledge,
[00:06:58.040]UCARE for funding this project and Colleen Steele of the conservation survey and
[00:07:02.960]decision division who ran our well query for us. And of course, Dr.
[00:07:07.430]Martha roads, my project mentor.

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Correlation between Nitrate and Nitrosatable Agrichemicals in Nebraska Groundwater and the Risk of Adverse Birth Outcomes

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