Hi this is Kiev Ackman again. Welcome back. Just talked briefly about how we're raising more food animals than ever. And in tighter geographic proximity than ever, and now we're going to get into why that may be problematic from a public health and environmental quality perspective. Let's start that discussion off by examining what we actually feed animals that we intend to eat. We feed food animals antimicrobial drugs and I guess the most commonly recognized antimicrobial group of drugs are antibiotics, and in certain classes of animals like cattle, we also feed synthetic hormones. As I mentioned earlier, later on in this lecture, we're going to go into far greater detail on the use of antibiotics in food animal production. We also feed food animals reprocessed animals that die during the production process and bi-products of food animals that are not considered fit for human consumption, like feather meal and we'll talk about that in a little bit. We routinely feed food animals animal waste. Poultry waste in particular is fed back to poultry and fed to cattle. And in some cases, we will feed animals waste from industrial processes. process is. One example of this is that the process waste from production of brass contains numerous minerals that are considered beneficial for animals die. Unfortunately, those process wastes also contains a number of heavy metals that are considered to be not nutritionally valuable and potentially hazardous to human health. We've talked about what we're feeding food animals but how much waste are we talking about when we think about 9.1 billion food animals being produced per year. To give you a little bit of perspective I wanted to show you some data on processed human sewage, that are often referred to as human bio solids. The US population produces about 6.9 million dry tons of processed sewage each year. And we apply a good fraction of that to the land, about 3.9 million dry tons. In comparison Animals raised for food in the US produce 287 million dry tons of waste per year. And we apply nearly all of that to land. And 1 key difference between human and animal waste is that we treat human waste before we, apply it to land. We treat it to remove metals. And we also treat it to kill pathogens. There's a lot of debate about how effective that treatment is but we're really not going to go into that here. The issue I'd like to discuss is that we almost never treat animal waste before applying it to land. In some cases, we let it compost in piles on fields or we may let it sit in a lagoon. But we do not go through thorough treatment processes before we land apply this fertilizer. And just to give you another factoid, we produce about a dry ton of animal waste for every US citizen each year. So it's quite a bit of waste and it poses some serious management challenges. So we've talked about what we feed food animals and we've talked about how much waste food animals generate, but what's in animal waste. Well, the first thing I think that you might hear about quite commonly, when thinking about animal waste, is the presence of bacteria. And some of those bacteria, because we feed animals antibiotics, may be resistant to many of the antibiotics that we use in human medicine. We also find protozoa, parasites in food animal waste. Certain viruses have been demonstrated to exist, and persist, for even up to a year in food animal waste. Food animal waste also has animal dander. Residues of some of those pharmaceuticals, some of the drugs that I mentioned before. Heavy metals, hormones, both naturally occurring hormones that animals excrete in their waste, and some of the Residues of the synthetic hormones that we feed certain types of food animals. And of course animal waste is rich in nutrients, nitrogen and phosphorus. Which is why it tends to be applied to land as fertilizer. We've talked about what's in animal waste, now what do we do with animal waste. I mentioned before that we apply most of it to agricultural land as fertilizer. In some cases we may store it first in hopes to reduce some of the pathogen loads, and we may store it in lagoons. And this is a picture of a newer lagoon here. And some cases we may stack it in fields in long piles called windrows. Recently there's been a lot of attention towards minimizing the impact of land applied manure on bodies of water like The Chesapeake Bay. So certain parts of the industry have set up some alternative treatment strategies to mitigate Some of those concerns. One of those strategies is development of poultry waste incinerators. There's a very prominent one operating right now that operates in Minnesota that burns turkey waste for energy and there are proposals to bring a number of these to various other states across the U.S., including North Carolina, Maryland And a few other places. This is a picture of a bag of pelletized poultry waste and this is something that I've spent quite a bit of time studying, I actually did some of my doctoral work around pelletized poultry waste and this bag is from a pelletization facility in Delaware that pelletizes a lot of the poultry waste that's generated on the Delmarva Peninsula and One reason this is seen as an alternative to land application, is that pelletized waste can be loaded into train cars, and then shipped west, or shipped elsewhere, where it can be sold in fertilizer stores for 25 bucks a pop. And the last alternative method for managing waste, that wanted to mention today was feeding a waste back to food animals as we actually mentioned before. Now, these management strategies pose risks to surrounding communities and environmental quality for a variety of reasons. I think first and foremost that the waste rarely stays where it is put. So, with land application of waste, there's concerns that certain weather events and precipitation events Are very good at mobilizing some of the nutrients but also some of the waste born contaminants, both horizontally via runoff and vertically through leeching into surface and ground water. Failed storage systems like the one pictured here, this is a ruptured manure lagoon can spread the contents into the surrounding area and surrounding bodies of water. Water, and given some of the micro-biological contaminants that are present in waste, these failures of storage systems are potentially of concern. Waste incineration will take any contaminants that are present in animal waste that are able to survive incineration like heavy metals and arsenic and introduce them into the air. Anything that isn't cleaned in an air scrubber prior to leaving an incinerator will stay behind in the ash product that's left over from the incineration process. And that ash product is then, as you may have guessed, sold as fertilizer. Animal-house ventilation can take any of the particulate or micro-biological contamination that's present inside of a production facility and spread it into the surrounding community. And, unfortunately, there's very little data on community and worker exposures to air from animal production facilities. There's also the potential for direct illegal releases of manure into surface waters and if you visit EPA's ag website, they actually have a listing of fines they've issued. For these releases. And what's interesting is the EPA has been heavily criticized over the years for being very lax in it's protection of surface waters from animal waste releases. So you can imagine the idea that they are actually reporting finds that they're giving means they're really sort of only getting the tip of the iceberg. What's really important to consider here is that a number of these pathways are opportunities for waste-born contaminants to actually get into ground water and what's really key to recognize is that ground water across the U.S. constitutes 40% of public water supplies. But for folks in rural areas, especially people who live around these types of operations Operations, most of them are really on ground water. It's uncommon in rural areas to see city delivered water, so there is a real potential for human exposure to these waste born contaniments. There are a number of other transport mechanisms that I haven't yet mentioned and I wanted to show you a couple of pictures. This is one I actually did mention, these are ventelation fans on the side of a poultry industrial food animal production facilty. And as you might imagine Anything that's in the air within the facility can be easily mobilized into the air surrounding these containment structures. This is a picture I took just upon arriving in Mexico on a sampling trip and we happened to get stuck behind a poultry transport truck. And research from colleagues here at Hopkins has actually demonstrated that poultry transport trucks are very effective methods of transporting bacteria that are resistant to antibiotics into surrounding communities. Workers are a wonderful vector, especially for transporting microbiological hazards from production facilities into the surrounding communities. Unfortunately, workers are rarely allowed to access to protective equipment. And in certain types of animal production, may have. Limited or no access to shower facilities to decontaminate themselves between work shifts, so they certainly are a means by which bacteria especially, but also viruses, can be spread. Collegues at Hopkins have also demonstrated that flies are very effective vectors for transporting bacteria from food animal production sites into surrounding communities. Flies have a residency of between 1 and 2 miles so for people who live in rural communities where animals are produced there are real risks of being exposed to bacteria as a result of deposition from flies. And the most commonly recognized transport mechanism is. Probably quite obvious to most of you and that's transmission of micro-biological hazards or maybe chemical contaminants through meat. I talked a little bit before about workers and I just wanted to speak specifically about how workers are really the front lines in terms of exposures to some of the contaminants that I talked about on animal waste and certainly some of the contaminants that are present in animal production facilities. And this is a picture I took on that same sampling trip in Mexico where we were doing some air sampling and I was able to catch a couple of pictures around one of the facilities we visited and this was certainly not an uncommon image among the farms we visited there and from what I've been told some of the farms here in the states as well. This young man has the unfortunate job of sweeping swine waste out of a facility and if you Actually have a look at the waste that he's pushed along to the wall there. And what you can't see in this photo is. If he were to continue to move in a forward direction, and, and push the waste, there's actually sort of a conveyor where all of the swine waste runs down the side of the building, and into a very large manure storage pit that's just wide open to the environment. So what's important to recognize is that there are 5 million documented farm workers and that includes both crop farm workers and workers in animal production facilities that may have routine contact via either direct contact with animals or through contact with animal waste that's used as fertilizer. So they may come into contact with those waste borne contaminants. There is no federal oversight of people who work in food animal production facilities. These facilities have a variety of exemptions under laws, that would normally require OSHA to actually set up standards for the workplace. So they are often unprotected. And as you've seen from some of the photos I've shown you. Industrial food animal production workers are often not afforded access to personal protective equipment that might help them minimize their exposures to some of the hazards that we've described in waste. So they're often unprotected and in some cases, especially in poultry production, those workers are not offered access to decontamination facilities like showers. Although research has shown that those showers can also be a source of exposure to certain pathogens as well. And lastly, many of the workers go home and spend time with their families and if they don't have adequate access to protective equipment or decontamination facilities, their families are at an increased risk of Developing infections or coming into contact with some of those waste borne contaminants. I've spoken a couple of times before about some of the concerns over air quality within animal production facilities, but let's go into some greater specifics about what's actually there. So there are wide array of airborne contaminants In these production sites. I think the most commonly recognized are certain gases like ammonia which is very common in poultry production facilities. And hydrogen sulfide which is particularly present in swine production facilities. There are also an array of papers that examine the composition of volatile organic compounds that are present at different food animal production facility types. One of the most recent papers was one from USDA that looked at a mixture of VOC's that are present in poultry houses and they speciated, or determined Unique chemicals, for about 60 different volatile organic compounds in swine production facilities of paper from earlier, in the 2000s documented 330 unique volatile organic compounds. What's interesting about those mixtures of volatile organic compounds, is that the majority of them are not toxicologically characterized, so We not only can't really make sense of what it means to be exposed to them individually, but we have even less information about what it means to be exposed to large mixtures of those chemicals. Animal production facilities tend to be very dusty places and have higher concentrations of particulate matter. I've mentioned, extensively, the presence of different bacteria viruses and protozoa that may become airborne, and available for exposure. Certain bacteria life may produce endotoxins that have been shown to link to human morbidity. And animal dander is increasingly becoming of concern. Concern because of its ability to elicit allergic responses. As I mentioned before, the health relevance of all of these is established, but for some of them we're just starting to understand how they might influence health. And lastly, I talked about VOC mixtures being challenging to understand because of the impact of mixtures, but we're talking about not only just mixtures of VOC's but mixtures of many different types of airborne pollutants and we have a very, very poor understanding of how they work together to impact health. So we've talked about workers. We've talked about the air quality inside of houses. Now, let's talk about rural communities that surround these production facilities. Now, I mentioned earlier in the lecture, that these types of operations tend to be geographically concentrated, so there are communities Where folks will have houses and those house may be bordered on one, two or three sides by animal production facility. And you can imagine that there are concerns that people who live in those houses have impacted quality of life. And may be at increased exposure to contaminants that emanate from those facilities. So there have been a number of epidemiologic studies that have looked at specific health outcomes associated with being exposed to those contaminants. And the majority have focused on respiratory and mental health outcomes but there's Documented relationships between exposure to food animal production contaminants and asthma prevalence, increased rate of hospitalization, irritation in a variety of organs including eye, nose and throat. There are studies that look at depression Anger and anxiety associated with living in close proximity to animal operations. There been small number of studies that have looked at relationships between reports of odor and measures of quality of life. And when you see the subsequent lecture from Steve Wing he's going to go into greater detail in some of these studies. And there is emerging literature on the economic effects of owning property, especially houses in Rural areas where animals are produced. And there have been demonstrations of decreased property values and property damage associated with living near one of these types of facilities or living near multiple animal production facilities. So in closing to this section of today's lecture I wanted to talk about a couple of challenges and actually conducting public health research on food animal production sites and characterizing the related public health impact. I mentioned before that we're dealing with a number of different types of stressors that are related to producing animals in the current dominant model and we're talking about exposure to chemicals. We're talking about exposure to bacteria viruses protozoa. But we're also talking about other types of stressors that are not always considered when thinking about environmental health hazards and those may be social hazards and economic hazards as well. We are talking about a number of different exposed populations who have different activity patterns that require in some cases separate evaluation or examination to study in order characterize exposure in examine outcome. We do know that certain types of people, or certain sub populations tend to be more highly exposed to these contaminants. And I think those in order of exposure would be workers and then fence line and surrounding communities. And lastly, consumers may suffer from Certain practices associated with the way that we produce food animals and I'll talk a little be more about that in the case studies. It can be challenging to relate some of the adverse effects to exposures due to access issues to rural communities and production sites. And that really speaks to the next bullet which is the integrated nature of animal production. Given these contractual arrangements between animal producers and the integrator companies it can be incredible challenging to get access to food animal production sites or animal. Processing sites, where the animals are converted from live animals into meat. You may imagine that an integrator company, that owns a processing plant, or holds a contract over an animal production site, may not be interested in allowing a public health researcher access to one of those sites. Because those researchers may find relationships between production practices. And risks or human illness. And that may. From an economic perspective, put an integrator in a vulnerable position. There really are no clear answers to getting over some of these research barriers. But I think what's important to recognize is there is a burden that's borne by the public in terms of concerns related to food safety. The people who are really. Bearing the burden of our current food production system are those workers in those rural communities, who really are the sort of the front lines facing these exposures. So anyways, that concludes the first part of today's lecture. The next step will be the case study on antibiotic use in food animal production.
