Acute Pesticide Poisoning in South Korea

by Kahea Kanuha

Occupational pesticide poisoning is a big health problem among agricultural workers, but there have been few studies on the differences, if any, in risk factors related to severity of pesticide poisoning. Kim et al. (2013) interviewed 1,958 male farmers in South Korea to explore work-related risk factors related to acute occupational pesticide poisoning according to the severity of the poisoning. It was found that the risk of acute occupational pesticide poisoning increased with total days of pesticide application, working on larger farms, not wearing personal protective equipment such as gloves or masks, not following pesticide label instructions, applying the pesticide in full sun, and applying the pesticide upwind. Continue reading

Pesticide Exposure May Degrade Human Cognitive Function

by Kahea Kanua

Pesticides are widely used toxins, yet research is only beginning to understand their effects on human brain and body functioning. In the United States, it is estimated that close to 8 billion dollars is spent on pesticides each year, yet only a few studies have examined the cognitive and neuropsychological impact of pesticide exposure, to mixed results. Schultz and Ferraro (2013) compared neuropsychological test performance of individuals with an occupational history of pesticide exposure to individuals with no such exposure history. The results suggested that occupational exposure to pesticides results in significant, and age-related, decline in some aspects of neuropsychological performance and information processing. Continue reading

Organophosphate Pesticides Cause DNA Damage in Rats

by Kahea Kanuha

The growing use of pesticides in large-scale agricultural applications as well as for household purposes has resulted in their widespread distribution in the environment. To see if pesticide exposure damaged DNA, Ojha et al. (2011) evaluated the genotoxicity of chlorpyrifos (CPF), methyl parathion (MPT), and malathion (MLT), three organophosphate pesticides, when given individually or in combination to rats. The results showed that even a single dose of CPF, MPT, or MLT caused significantly high levels of DNA damage in all the rat tissues examined. DNA damage was also observed in microscopic examinations of tissue samples from the liver, brain, kidney, and spleen of rats exposed to one or more pesticides. It was also observed that the damaged DNA is repaired by the endogenous repair systems with time. When the pesticides are given together, they do not potentiate …

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Pesticide Concentrations in Stream Sediments from Three Farm Management Approache

The relative impacts of organic, integrated, and conventional sheep and beef farms on the physical and chemical properties of streams have been studied in the past, as well as the impact on stream macroinvertebrates. To determine if these different farming practices affect pesticide residues in streams, Shahpoury et al. (2013) quantified chlorinated pesticides in 100 sediment samples from 15 streams in New Zealand, finding that streams in all three farming categories contained pesticides in the stream sediment, but sediments from conventional farms contained significantly higher concentrations of dieldrin, endosulfans, current-use pesticides, and chlorinated pesticides compared to organic and integrated farms. —Kahea Kanuha

Shahpoury, B., Hageman, J., Matthaei, C., Magbanua, S., 2013. Chlorinated pesticides in stream sediments from organic, integrated and conventional farms. Environmental Pollution 181, 219-225.

There is an increasing global interest in understanding how different farm management approaches affect the environment. Three such management approaches are organic, integrated, and conventional. Organic farming avoids the use of synthetic pesticides and fertilizer, with the goal of using environmentally sustainable approaches to farm management. Conventional farming uses these chemicals. Integrated farming aims to achieve optimal results by finding a balance between the economic benefits of synthetic fertilizers and pesticides and their environmental costs. Pesticides are of an increasing concern because they often have unintentional impacts on non-target organisms and may accumulate in the tissue of animals and humans. In addition, they persist in the environment for a long time and may continue to have environmental impacts long after initial application.
Shahpoury et al. collected sediment samples from 15 streams passing through sheep/beef farms on the South Island of New Zealand. The farms were arranged in clusters at five locations, each cluster comprising three neighboring farms using different farm management techniques: organic, conventional, and integrated. Sediment sample extracts were analyzed for 19 legacy pesticides and 5 current-use pesticides. The current-use pesticides selected for this analysis have been widely applied, previously detected in groundwater systems, are highly toxic compared to other pesticides, and have high volatilization potentials, making them prone to vapor drift from and between farms.
To more easily understand the data, the pesticide concentrations were split into groups for analysis: dieldrin, endosulfans, current-use pesticides, and all pesticides. Dieldrin was originally developed in the 1940s as an alternative to DDT and was widely used in the 1950s—1970s. However, long-term exposure has proven toxic to a wide range of animals, including humans; dieldrin has been linked to a range of human health problems and is now banned in most of the world. Endosulfans are highly toxic insecticides banned in New Zealand in January 2009. Current-use pesticides are pesticides registered for use in New Zealand when the sampling took place, while legacy pesticides are pesticides, often very toxic, applied in the past that have remained in the environment.
For each of these pesticides or pesticide groups, mean concentrations were found to be highest in stream sediments from conventional farms. A previous study of the same 15 sheep/beef farming streams found that stream macroinvertebrate communities were more degraded in streams passing through conventional farms than through integrated or organic farms. It is certainly possible that the higher pesticide concentrations found in stream sediments from conventional farms have contributed to the macroinvertebrate community degradation.

Chlorinated pesticides were found throughout the study areas regardless of the farm management strategies applied during the 8—11 years preceding the study. One explanation of this is the high volatilization potential of some pesticides. This results in the pesticides being volatized or evaporated into the air and then carried by wind into a different area. As the impacts and concentrations of pesticides are further studied, it seems clear that pesticide use in farming often has unintended and long-range impacts on areas different from those where pesticides were originally applied.

Effects of agricultural pesticides on the health of Rana pipiens frogs

The balance of natural ecosystems is almost certainly being disturbed by human modification of the natural environment. One such modification is the use of pesticides, which may leak into the surrounding soil and water and influence the surrounding ecosystems. Prior lab results have shown that pesticides could affect the health status of amphibians. To verify if similar results would be seen in natural populations, Cristin et al. (2013) sampled leopard frogs at three contaminated sites and two reference sites and used size, weight, spleen cellularity, phagocytic activity, and other measurements to examine the differences between frogs collected from contaminated sites and reference sites. The results of the study show that the juvenile frogs exposed to agripesticides are smaller in weight and length. It was also found that the number of active phagocytes, cells that protect the body by ingesting potentially harmful foreign particles and bacteria, was significantly reduced in exposed frogs. Thus pesticide use may inhibit amphibian growth and immune system response. —Kahea Kanuha

                  Christin, M.S., Menard, L., Girous, I., Marcogliese, D.J., Ruby, S., Cyr, D., Fournier, M., Brousseau, P. 2012. Effects of agricultural pesticides on the health of Rana pipiens frogs sampled from the field. Environmental Science and Pollution Research published ahead of print September 21, 2012, doi: 10.1007

                  Cristin et al. began by selecting five study sites: three contaminated sites and two reference sites along the tributaries of the St. Lawrence River in Monteregie, Quebec, Canada. The contaminated sites were directly adjacent to agricultural land and were therefore exposed to pesticide runoff. The reference sites included a conservation wetland and a wetland within a rural park, with managed landscape and human activity nearby. Pesticide concentrations were measured through collections of surface water samples. Repeated sampling was necessary since pesticide concentrations may fluctuate considerably with rain patterns and pesticide application time in the surrounding crop fields. For each site, temperature, conductivity, pH, and nitrate concentrations were recorded.
                  Juvenile R. pipiens were captured at the end of July and the beginning of September at each of the five sites. Overall health of the frogs was quantified through measurements of length and weight. The body index, or ratio of weight to length, was used rather than the measurements themselves in subsequent analyses.
To determine immune response impairment, the authors examined the viability of splenocytes, cellularity, and phagocytosis. Splenocytes are white blood cells produced in the spleen, and play an important role in immune system response. The spleen of each animal in the study was removed and cell suspensions were then prepared. Cellularity is the number and type of cells present in a given tissue. Viability, essentially the amount of living cells, was measured to ensure cell extraction methods were effective and that there were enough living cells to proceed with phagocytosis analysis. Both cellularity and splenocyte viability were determined microscopically after trypan blue dye exclusion, which stains dead cells blue.
Phagocytes are cells that ingest harmful foreign particles to protect the body and constitute the first line of defense against infectious microorganisms. Phagocytic activity of splenocytes was determined by introducing fluorescent bacteria to the spleen cells, incubating the cells, and then collecting the fluorescence emission. Higher fluorescence emissions indicate higher bacteria count and thus less phagocytic activity.
The results indicate that frogs living in sites exposed to pesticides runoff are smaller in length and weight
                  In both July and September, frogs living in agricultural regions had significantly lower body indices than frogs sampled in reference sites. In addition, there were no significant differences of body indices between the two reference sites. Spleen cellularity results show significant decreases in the number of splenocytes for frogs sampled in the three contaminated sites. However, in September one of the reference sites showed a number of splenocytes six times higher than the other reference site. Viability for all groups of frogs captured was over 70%, indicating the splenocyte suspensions were suitable to be used in the phagocytosis assay because there were enough living cells. The phagocytosis results for frogs sampled in July show a significant decrease in phagocyte numbers for four of the five contaminated sites. The September results show a significant decrease in two of the contaminated sites. In both months there was no significant difference between the reference sites.
                  It has already been observed that pollutants can reduce tadpole growth, but the exact way in which contaminants impair growth is not fully understood. Contaminated environments may hasten a tadpole’s metamorphosis in order to escape from a poor growing environment, which leads to a smaller size. However, the smaller size of frogs sampled from contaminated sites in this study may be due to other reasons, such as physiological effects of contaminants on growth or food limitation due to low food quality. The specific interactions between pesticides and the immune system also warrant further investigation in order to fully understand the impact of agricultural practices on aquatic systems.

This study has shown that juvenile frogs exposed to agripesticides are smaller and have compromised immune systems compared to frogs captured in reference sites. Further studies on almost all aspects of the relationship between agrochemicals and ecosystem response are necessary to more fully understand the complex consequences of human actions.

Agricultural Pesticide Use Decreases Species Richness in Stream Invertebrates

Despite years of scientific studies to guide regulation efforts, it is unknown to what degree agricultural pesticides cause species losses and thus a decrease in total biodiversity. To examine this relationship, Beketov et al. (2013) analyzed the effects of pesticides on taxa richness of stream invertebrates, using additional analyses to discriminate the possible confounding factors from the effects of pesticides. In all study sites it was shown that pesticide use caused a loss in species and family richness, indicating that pesticide use should be considered a main driver of regional biodiversity loss. —Kahea Kanuha
Beketov, M., Kefford, B., Schafer, R., Liess, M., 2013. Pesticides reduce regional biodiversity of stream invertebrates. Proceedings of the National Academy of Sciences 110, 11039—11043.

                  Beketov et al. applied the contaminant category richness to study the impacts of pesticide use on freshwater stream invertebrates. Contaminant category richness describes the taxa richness of stream invertebrates particular to different water contaminant levels, quantified by the relationship between the number of individuals and the number of taxa recorded. Data were used from Europe (33 sites) and Australia (18 sites) and included pesticide exposure assessment, stream invertebrate records, and data on environmental factors that may compound the effects of pesticides.
                  Study sites were assigned a contamination category based on toxic units (TUs) computed from the maximum pesticide concentrations at peak water runoff events. The contamination categories were then compared to the species and family richness of each respective study site. The Chao 2 richness estimator used the collected data to predict the species richness for an infinite number of samples taken at each site. Results show significant differences in taxonomic richness among all contamination categories. The percentage decrease in taxonomic richness between the uncontaminated and highly contaminated sites ranged from 27%, from the Australian family-level data, to 42%, for the European species-level data. Such an extensive decline is comparable to the effects of other known drivers of biodiversity loss. This indicates that for the goal of slowing biodiversity loss, safer standards should be set for pesticide use, methods, and mitigation practices.
                  Two methods were used to discern the possible effects of confounding factors from the effects of pesticide use. In the first, the SPEAR approach was used to identify the taxa that are particularly vulnerable to pesticides. After these taxa were identified, the data were checked to see whether the overall declines in taxa richness were based on the losses of taxa particularly vulnerable to pesticide use. As expected, it was found that pesticide contamination was associated with a decrease in the number of pesticide-vulnerable taxa. Secondly, available water quality and habitat variables were analyzed to see if any of them would explain the differences between contamination categories. The only significant difference found was in electrical conductivity between the slightly and heavily contaminated sites in Australia, but it was not a consistent linear trend and thus it is unlikely to be a major driver of the observed diversity patterns.

                  The effects of pesticide use on the taxa richness in Europe were identified in the contaminant concentration level that is considered to be protective by current European agricultural pesticides regulation. This indicates that current standards are not high enough to protect stream biodiversity. Agricultural pesticide use is predicted to increase in the coming decades due to the effects of climate change, and without more stringent regulation it may become an even more important driver of biodiversity loss in the future.