It is likely that soil maggot pest pressure on broccoli is generally lower in the Imperial County and Fresno County, where summers are hot and dry, than in the cooler, moist Central Coast climate where the pest thrives. If the pest pressure was even moderately higher in the Central Coast than the other regions, yet Central Coast growers still decided to stop using chlorpyrifos on broccoli for maggot control, the 2012 Ag Waiver could have played a role in suppressing the chemical in the region. In the case of diazinon, there was an even greater drop in use, not only in lettuce , but in all crops in all three counties. While the 2012 Ag Waiver could have acted as the final nail in diazinon’s coffin, it seemed that diazinon’s fate was already determined, perhaps because partly due to the strict federal label restriction greatly limiting the use of the chemical on all crops except a few.Logically, less pesticide use should equate to less pesticide presence in waterways, and less harm to humans and other living organisms. Previous studies and technical reports cite a strong correlation between pesticide use and surface water detections . The CDPR databases also offer a valuable means of establishing a correlation between pesticide use and detection. In addition to their Pesticide Use Records, the CDPR hosts an extensive database of surface water quality data documenting the presence of pesticides in waters throughout the state. However, plastic flower bucket more limited are studies and information that take the next step in linking the application of pesticides in Central Coast waters to toxicity to living organisms.
While there are a number of individual peer reviewed journal articles offering single case and often short term evidence of a relationship between pesticide use and toxicity; the CMP is one of the limited number of regional monitoring programs that provides consistent longitudinal data as a basis for understanding if and how regional water quality is fairing in response to declining chlorpyrifos and diazinon use, however even this dataset is relatively new and limited in geographic scope and the number of sampling sites. Beginning in 2005, the CMP initiated this new database with the aim of examining the relationship between organophosphates, in particular, and toxicity toaquatic invertebrates. The CMP collects water quality monitoring samples from over 20 sites and analyzes each for organophosphate compounds as well as tests samples for toxicity to invertebrates, fish and algae. Although these data are not part of specific Agricultural Waiver requirements, this additional toxicity project was conducted as a collaborative endeavor between CMP and the Regional Board . Since the beginning of the program, water quality samples have found diazinon and chlorpyrrifos to be pervasive in the Central Coast, and frequently at concentrations of known toxicity to aquatic invertebrates . These results corroborate with individual scientific studies throughout the Central Coast conducted by the Granite Canyon Lab and researchers at the CDPR . More recent information from this database reveals toxicity to aquatic invertebrates as well as fish have largely improved through 2013, and possibly through 2014; however, toxicity to invertebrates in sediment has regressed over that time .
These data suggest that the decline in chlorpyrifos and diazinon use is likely contributing to a decline in toxicity to aquatic invertebrates, and that other pesticides, such as pyrethroids, which remain in high use and are less regulated, may be contributing to a growing sediment toxicity problem. Although the CDPR’s dataset, Surface Water Database , is more limited than CMP’s in the diversity of water quality information it reports, the SURF database is rich in quantity and geographic scope. The database contains over 554,000 chemical analysis records in 58 California counties from over 3,000 samples sites. SURF is categorized by county, rather than region, and reports the presence of pesticides in state waters from various studies conducted by federal, state and local agencies, private industry and environmental groups. To assess relevant SURF data from Monterey County for use in this study, the database was queried by county and chemical . The query provided 459 data points/water samples from 2003 to 2014 for chlorpyrifos, and 465 data points over the same time period for diazinon. No data was available for 2006. The data were catalogued by number of samples and detection frequency. In addition, I calculated the exceedance frequency per chemical per year based on California Department of Fish and Wildlife’s freshwater quality criteria for chlopyrifos and diazinon . Percent of detection frequency was calculated using the number of detections per total samples per year, and the percent of exceedance frequency was calculated using the number of exceedances per total samples in a given year. Results from these calculations suggest that diazinon and chlorpyrifos detections and exceedances are rapidly declining in the Monterey County , as expected from the decrease in their use in recent years.
While there is strong evidence to suggest that diazinon and chlorpyrifos presence in Central Coast waterways are declining, it is too soon to judge if the water column toxicity problem has been solved. Several factors could explain why water toxicity could linger even after diazinon and chlorpyrifos were almost unilaterally abandoned. First, even if the majority of growers discontinue use of the two pesticides that most cause most water column toxicity, a few heavy polluters can continue to wreak havoc on waterways. Additionally, chlorpyrifos is bound partially to sediment creating the possibility of re-mobilization in the stream system. If chlorpyrifos does remain in a stream, the pesticide could be detected at toxic levels for a period of time after it came off a farm. Thirdly, continued use of malathion, and to a lesser extent pyrethroids, could be contributing to water column toxicity. Malathion, a third organophosphate pesticide, has similar chemical properties to diazinon and chlorpyrifos and has been known to contribute to water column toxicity. And although the vast majority of pyrethroids tend to attach to sediment particles, some pyrethroids are water-soluble and could be a source of water toxicity. Despite incomplete evidence, water column toxicity due to chlorpyrifos and diazinon has largely been written off as resolved. Due to budget and staff constraints, the great need to prioritize TMDLs has forced the Central Coast Regional Board to move onto the next pressing,flower buckets wholesale and arguably more difficult pollution problem: sediment toxicity due to pyrethroids.Calling out just two chemicals in the 2012 Central Coast Ag Waiver has resulted in a de facto ban. While the elimination of any very problematic chemicals can have desirable affects on human health, aquatic organisms and water quality, the resulting improvements can only be as good as the resulting behavioral consequences. When the 2012 Agricultural Waiver was implemented, Central Coast growers had a choice to respond to the policy decisions in several ways. While growers had the option of 1) carrying on with the use of chlorpyrifos and diazinon, as long as they complied with increased policy mandates, almost all decided to instead halt their use of chlorpyrifos and diazinon by 2) putting up with more crop damage, 3) experimenting with other chemicals, or 4) switching to organic. Each of these actions carries a mixed bag of policy, environmental and societal implications. The first option, complying with tier 3 policy mandates, would have substantially bolstered policy objectives relating to the Ag Waiver’s monitoring program despite greatly hindering water quality objectives. A central goal of requiring individual surface water monitoring of tier 3 farms was to evaluate the effects of farm discharge on water quality and beneficial uses. Individual surface water monitoring on all tier 3 farms, or 10% of farms as estimated in 2010, would have contributed momentously to this goal. However, the benefits of less harmful pesticides in regional waterways far outweigh the added information that would have been gathered if growers had stayed in tier 3 and continued using diazinon and chlorpyrifos.
Instead, most decided to ditch chlorpyrifos and diazinon to escape individual monitoring requirements and/or protect the environment and workers. Some growers decided to simply put up with more crop damage, which could be especially costly for a small farm with thin profit margins or if and when pests became unmanageable without alternative control measures. Though individual farms may have experienced a financial squeeze as a result of giving up the chemicals, economic data show that Central Coast lettuce and broccoli growers on average are thriving,producing more crops at a higher crop value, despite abandoning use of both chemicals. Switching to organic farming practices offers another possible option of increasing profits when abandoning pesticides. While fewer chemicals could yield positive environmental and human health results, the cost in both producing and purchasing more expensive organic crops could cause possible distributional effects. For example, entry into the organic industry might not be economically feasible for all farms. Farms with sales over $5,000 must pay for organic certification in order to label their products as organic. While price premiums for their products could cover the initial entry cost, for some small businesses this added expense imposes too hefty an economic barrier to become organically certified . Another potential distributional effect is who is benefitting from organic production, both on the consumer and production end. Historically, organic products were more exclusively available in niche food and health stores, and often at a much higher premium; from 1990-1996, natural food stores sold two-thirds of all organic products in the U.S. . Consequently, wealthy, white, and more educated consumers made up the majority of the organic consumer base. Encouragingly, in recent years the number and diversity of consumers of organic products is expanding , at least partially due to increased accessibility of organic products—as of 2000, more organic food was purchased in conventional supermarkets than in any other venue . On the production end, the switch to organic could have profound implications for farm workers; however, research is showing that organic systems might not change working conditions as much as society might expect. While clear benefits of working on an organic versus conventional farm may include less exposure to harmful pesticides, a clear health and lifestyle benefit, a recent California study shows that other socio-economic perks that are often expected of organic agriculture, such as higher wages and benefits trickling down from higher price premiums, multi-cropping farming systems, more likelihood of year-round employment and overall healthier working conditions, are more of the exception rather than the rule . Focusing regulation too narrowly on a small subset of pesticides could have encouraged a third, more damaging farm management response – switching to more harmful pesticides. In the case of California’s Central Coast, while it appears that there has not been an absolute transference from chlorpyrifos or diazinon to a single alternative pesticide, there is some evidence, albeit inconclusive and incomplete, that growers have switched to other, more harmful chemicals. Interestingly, the trend of chemical switching from organophosphates to pyrethroids, was identified several years prior to the Ag Waiver. In a 2008 Regional Board report on toxicity problems in the Central Coast, the Board staff found that “pyrethroids are a newer class of pesticides that are replacing diazinon and chlorpyrifos for both urban and agricultural uses.” Additionally, as Joseph and Zarate’s article points out, brassica growers in the region are on the hunt for new pesticides to control cabbage maggots since chlorpyrifos and diazinon are no longer viable options. Their research has found ahandful of pyrethroid pesticides and a neonicotinoid pesticide to be as effective or more effective than chlorpyrifos in maggot control; and many of these alternatives have a significantly longer half-life and different chemical properties than organophosphates. Regulating a pesticides, or even nitrates with longer half-lives and/or ones that bind to sediment is further complicated by the time lag in water quality response. The same individual monitoring requirements would unlikely pinpoint a deleterious polluter until well after their lease is up or they have retired, leaving legacy harms that cannot be quickly undone and making it difficult for water quality regulators to address. Upcoming classes of pesticides targeted in the most recent Central Coast sediment toxicity TMDLs, pyrethroids, are especially prone to this issue.