Chemicals and biological products used in south-east Asian shrimp farming, and their potential impact on the environment — a review

A wide variety of chemicals and biological products are used to treat the water and sediment of ponds in semi-intensive and intensive south-east Asian shrimp farming. These products are also often used in shrimp hatcheries and to disinfect equipment for shrimp pond management. In spite of the size and importance of the shrimp farming industry in several south-east Asian countries, documentation of the quality and quantity of chemicals and biological products used during farming is scarce. This paper is a compilation of the literature available on substances used in shrimp farming, and the possible environmental effects of these products are analysed to the extent allowed by the limited information. The role of shrimp farm managers, the chemical industry, governments, inter-governmental organisations and scientists in the development of a sustainable practice is discussed. It is concluded that shrimp farmers should reduce the use of chemicals and biological products because of the risks to the environment, human health and to production, and also, because many chemicals and biological products used in pond management have not been scientifically shown to have a positive effect on production. Clearly, the use of some chemicals, i.e. certain antibiotics, poses a risk of danger towards human health. Some chemicals used in shrimp farming, such as organotin compounds, copper compounds, and other compounds with a high affinity to sediments leave persistent, toxic residues, and are likely to have a negative impact on the environment. However, to assess the reality of these risks, substantial new information about the quantity of chemicals used in marine south-east Asian shrimp farming is needed.     

Municipal landfill leachates: A significant source for new and emerging pollutants

Landfills have historically remained the most common methods of organized waste disposal and still remain so in many regions of the world. Thus, they may contain wastes resulting from several decades of disposal and decomposition with subsequent release of organic compounds that may have environmental, wildlife and human health consequences. Products containing different types of additives with unique beneficial improvement properties are in daily use. However, when these products are decomposed, additives are release into the environment, some of which have been shown to have negative environmental impacts, resulting in the ban or at least restricted application of some chemicals. New and emerging compounds are continuously discovered in the environment. Herein, we report qualitative and quantitative data on the occurrence of new and emerging compounds with increasing environmental and public health concern in water- and particle phase of landfill leachates. Under normal environmental conditions, several of these chemicals are persistent high-volume products. Identified chemicals in the leachates at nanogram (ng) or microgram (μg) per liter levels include — chlorinated alkylphosphates such as tris(1-chloro-2-propyl) phosphate (TCPP), N-butyl benzensulfonamide (NBBS), the insect repellent diethyl toluamide (DEET) and personal care products such as the non-steroidal anti-inflammatory drug ibuprofen and polycyclic musk compounds. Among new and emerging contaminants, perfluorinated compounds (PFCs) were measured in the water phase at concentrations up to 6231 ng/L. Compared with the other chemicals, PFCs were primarily distributed in water phase. An effective removal method for PFCs and other polar and persistent compounds from landfill leachates has been a major challenge, since commonly used treatment technologies are based on aeration and sedimentation. Thus, the present study has shown that municipal landfill leachates may represent a significant source of concern for legacy, new and emerging chemicals in groundwater.     

Household hazardous waste in municipal landfills: contaminants in leachate

Household hazardous waste (HHW) includes waste from a number of household products such as paint, garden pesticides, pharmaceuticals, photographic chemicals, certain detergents, personal care products, fluorescent tubes, waste oil, heavy metal-containing batteries, wood treated with dangerous substances, waste electronic and electrical equipment and discarded CFC-containing equipment. Data on the amounts of HHW discarded are very limited and are hampered by insufficient definitions of what constitutes HHW. Consequently, the risks associated with the disposal of HHW to landfill have not been fully elucidated. This work has focused on the assessment of data concerning the presence of hazardous chemicals in leachates as evidence of the disposal of HHW in municipal landfills. Evidence is sought from a number of sources on the occurrence in landfill leachates of hazardous components (heavy metals and xenobiotic organic compounds [XOC]) from household products and the possible disposal-to-emissions pathways occurring within landfills. This review demonstrates that a broad range of xenobiotic compounds occurring in leachate can be linked to HHW but further work is required to assess whether such compounds pose a risk to the environment and human health as a result of leakage/seepage or through treatment and discharge.     

Detection of mutagenic/carcinogenic compounds in unused and used motor oils

The discharge of used motor oils in the environment poses public health problems because of the mutagenic/carcinogenic compounds in them. Among these hazardous chemicals, polycyclic aromatic hydrocarbons (PAH) are of particular interest since the carcinogenic properties of some of them are known. The authors have applied the Salmonella/microsome test, coupled with two preparation methods of samples, to motor oils of different brands, both before and after use in car petrol engines. A PAH determination method was also studied. The results showed the unused motor oils to be non-mutagenic and to contain traces of PAH, while the used motor oils of the samples taken according to both preparation methods were highly mutagenic and contained a much higher quantity of mutagenic/carcinogenic PAH.     

Antibiotic resistance in bacteria from shrimp farming in mangrove areas

Shrimp farming is a sufficiently large and mature industry to have an effective range of antimicrobial agents for most bacterial diseases in shrimp culture. However, at present, there exists great concern over the widespread use of antibiotics in aquaculture, which may result in residue of antibiotics in water and mud, and subsequently, the development of antibiotic resistance in bacteria in the environment. There is limited understanding about the effect of antibiotic residues on bacteria resistance in shrimp farming environment. Therefore, a study was conducted to investigate bacterial resistance to Norfloxacin (NFXC), Oxolinic Acid (OXLA), Trimethoprim (TMP) and Sulfamethoxazole (SMX), which were found in four shrimp farming locations in mangrove areas in Vietnam. Findings indicate that there is a relatively high incidence of bacteria resistance to these antibiotics observed in most of the studied sites, particularly to antibiotics with concentration of 0.1 microg/ml. Yet the relation between concentration of antibiotic residues and incidence of antibiotic resistance is not clearly defined. Among individual antibiotics, the incidence of resistance to TMP and SMX was higher than the others. Identification of bacteria isolated from mud samples by DNA analyzer shows that Bacillus and Vibrio are predominant among bacteria resistant to the antibiotics. The result of the study also indicates that these antibiotics in media degraded more rapidly due to the presence of resistant bacteria.     

Environmental and health hazard ranking and assessment of plastic polymers based on chemical composition

Plastics constitute a large material group with a global annual production that has doubled in 15 years (245 million tonnes in 2008). Plastics are present everywhere in society and the environment, especially the marine environment, where large amounts of plastic waste accumulate. The knowledge of human and environmental hazards and risks from chemicals associated with the diversity of plastic products is very limited. Most chemicals used for producing plastic polymers are derived from non-renewable crude oil, and several are hazardous. These may be released during the production, use and disposal of the plastic product. In this study the environmental and health hazards of chemicals used in 55 thermoplastic and thermosetting polymers were identified and compiled. A hazard ranking model was developed for the hazard classes and categories in the EU classification and labelling (CLP) regulation which is based on the UN Globally Harmonized System. The polymers were ranked based on monomer hazard classifications, and initial assessments were made. The polymers that ranked as most hazardous are made of monomers classified as mutagenic and/or carcinogenic (category 1A or 1B). These belong to the polymer families of polyurethanes, polyacrylonitriles, polyvinyl chloride, epoxy resins, and styrenic copolymers. All have a large global annual production (1-37 million tonnes). A considerable number of polymers (31 out of 55) are made of monomers that belong to the two worst of the ranking model's five hazard levels, i.e. levels IV-V. The polymers that are made of level IV monomers and have a large global annual production (1-5 million tonnes) are phenol formaldehyde resins, unsaturated polyesters, polycarbonate, polymethyl methacrylate, and urea-formaldehyde resins. This study has identified hazardous substances used in polymer production for which the risks should be evaluated for decisions on the need for risk reduction measures, substitution, or even phase out.     

Standardized tests fail to assess the effects of antibiotics on environmental bacteria

Pharmaceuticals are designed and used because of their specific biological effects. Over the past decade, compounds from various classes of pharmaceuticals have been detected in the environment. Concern has grown about the adverse effects pharmaceuticals in the environment might potentially have on human and ecological health. A sound risk assessment is therefore urgently needed for pharmaceuticals. Standardized tests for assessing the effects of chemicals on environmental organisms are widely used for this purpose. However it is questionable whether classical standardized tests give reliable data needed for environmental risk assessment. In this study we investigated the suitability of the respiration inhibition test OECD 209 for the assessment of the effects of antibiotics, disinfectants and cytotoxics on sewage sludge bacteria. We found that inhibition concentrations can strongly depend on the test period and the type of compound. We conclude that tests to assess the effects of pharmaceuticals on environmental organisms such as bacteria have to be evaluated before their results can be used in environmental risk assessment.     

Pre-treatment and bioconversion of wastewater sludge to value-added products—Fate of endocrine disrupting compounds

Development of processes for the production of value added products (VAPs), such as biopesticides, microbial inoculants or industrial enzymes through biotransformation of raw or pre-treated wastewater sludge (WWS) has undergone a substantial progress over the last decade. WWS based VAPs are low cost biological alternatives that can compete with chemicals or other cost intensive biological products in the current markets. However, when WWS is used as a raw material for VAPs production, questions still remains on the persistence of organic pollutants within the biotransformed WWS, especially, endocrine disrupting compounds (EDCs) and the production of their toxic intermediates. WWS pre-treatment prior to biotransformation as well as the microbial strains used for biotransformation can possibly remove these organic pollutants. The literature findings concerning the impact of WWS pre-treatment and value added products on EDCs removal are reviewed in this paper. The microbial potential to degrade or detoxify EDCs and toxic intermediates concomitant with value-addition is also discussed. The concept of obtaining EDCs free-WWS based VAPs and simultaneously achieving the objective of pollution control is presented.     

Acute toxicity of 12 industrial chemicals to freshwater and saltwater organisms

Aquatic animal toxicity is a major criterion used by the U.S. EPA to designate and classify hazardous substances other than oil. This research developed basic toxicity data for twelve industrial chemicals with which little or no previous testing had been done. Static 96h toxicity tests were performed with one freshwater species (fathead minnow, Pimephales promelas) and one saltwater species (grass shrimp, Palaemonetes pugio or white shrimp, Penaeus setiferus) on the following chemicals: ammonium fluoride, arsenic trisulfide, benzoyl chloride, benzyl chloride, cupric acetate, o-dichlorobenzene, p-dichlorobenzene, mercuric acetate, mercuric thiocyanate, resorcinol, sodium hypochlorite and toluene-2,4-diisocyanate (TDI). As defined by 96 h LC50's ≤ 500 mg l⁻¹, all 12 chemicals were hazardous to freshwater minnows, and all but TDI were hazardous to saltwater shrimp. The physicochemical behaviors of the compounds greatly influenced their aquatic toxicities.     

Time-trends of metals and organic contaminants in sewage sludge

The occurrence of chemicals in sludge from sewage treatment plants (STPs) is of concern for human health and the environment. Legislations and regulations are put in place to minimize the release of harmful chemicals into the environment and arable land, e.g. via application of sewage sludge. Temporal trends analysis of sludge contaminants can be used to assess the effectiveness of such actions. Such analyses can be performed retrospectively, using sludge stored in environmental specimen banks, to investigate new or emerging environmental contaminants. The present study provides data from time-trend analyses of metals, persistent organic pollutants, pharmaceuticals, personal care products, and other organic compounds in sludge from Swedish. The analysis showed that sludge is a suitable matrix for time-trend studies and it can take on average 12 years (range, 5-26 years) to track an annual change of ±10% (with a power of 80%). Statistically significant trends were found for 18 out of the 77 compounds subjected to analysis, of which 75% showed decreasing trends. Triclosan and the antibiotic norfloxacin followed the same trend as the national recorded usage and decreased annually by 65% and 60%, respectively. The opposite was true for the methylsiloxanes, which showed an annual average increase of about 30%. A downward trend (about 20% year⁻¹) was observed for the polybrominated diphenylethers (PBDEs 154 and 183), while PBDE 209 increased by 16%. Further measurements are required to determine if the substitution of PBDEs by chlorinated paraffins or organophosphorus compounds have resulted in increased concentrations of the latter in sludge.     

Critical loads of acidity for surface waters in China

Various types of partition coefficients have been used to facilitate the prediction of the concentration of pollutants in different phases in the environment. Many thousands of chemicals may exist in our environment which makes prediction work difficult or impossible due to a deficiency of knowledge of those unfamiliar compounds. In this study, the correlation between an octanol-water partition coefficient (Kow), water solubility (S) and a normalized soil/sediment partition coefficient (Koc) was investigated though the examination of 148 model chemicals. These model chemicals were classified into five major categories for easier adoption in future use. They are aliphatic compounds, aromatic compounds, pesticides, herbicides and polyaromatic hydrocarbons (PAH). Linear models are developed to correlate these partition coefficients in each category. The prediction of unfamiliar chemicals in the same category becomes possible if the fundamental properties of these chemicals (such as solubility) are previously known.     

Characterization of roadway stormwater system residuals for reuse and disposal options

The chemical characterization of sediments accumulated in catch basins and stormwater ponds provides important information for assessing risks associated with management of these residuals upon removal of accumulated deposits in stormwater systems. In this study, over a period of 15 months, more than 150 residual samples were collected from 77 catch basin units and 22 stormwater ponds from 16 municipalities throughout the state of Florida. Concentrations (mg/kg) of metals and metalloids (arsenic, barium, cadmium, chromium, copper, lead, mercury, nickel, selenium, silver, and zinc) and trace organics (volatile organics, semi-volatile organics, herbicides, and pesticides) in the sediments were measured. In addition, the synthetic precipitation leaching procedure (SPLP) was utilized to evaluate pollutant leachability risk for a subset of the samples collected. Measured pollutant concentrations were compared to corresponding risk-based guidelines in Florida (i.e., Florida soil cleanup target levels) to assess potential human health risks of beneficial use of these residuals through land application. Leached concentrations were compared to risk-based water quality guidelines (i.e., Florida groundwater cleanup target levels) to examine the potential for groundwater contamination. Although several metals (arsenic, barium, chromium, copper, nickel, lead, and zinc) were routinely detected in the catch basin and stormwater pond sediments, their concentrations were generally lower than the Florida's risk-based cleanup target levels for soils. A small number of organochlorine compounds (e.g., 4,4′-DDE, 4,4′-DDT) were detected, but only in a limited number of the samples (less than 10%); leaching of trace organic pollutants above the Florida risk-based groundwater thresholds was rare. The results suggest that when land-applied or beneficially used, these residuals are not expected to pose a significant threat to human health or the environment and the results of this research will provide stormwater managers and environmental management authorities with a useful resource to examine proper disposal and beneficial use of catch basin and stormwater pond sediments.     

Occupational exposure and health risks of volatile organic compounds of hotel housekeepers: Field measurements of exposure and health risks

Hotel housekeepers represent a large, low-income, predominantly minority, and high-risk workforce. Little is known about their exposure to chemicals, including volatile organic compounds (VOCs). This study evaluates VOC exposures of housekeepers, sources and factors affecting VOC levels, and provides preliminary estimates of VOC-related health risks. We utilized indoor and personal sampling at two hotels, assessed ventilation, and characterized the VOC composition of cleaning agents. Personal sampling of hotel staff showed a total target VOC concentration of 57 ± 36 µg/m³ (mean ± SD), about twice that of indoor samples. VOCs of greatest health significance included chloroform and formaldehyde. Several workers had exposure to alkanes that could cause non-cancer effects. VOC levels were negatively correlated with estimated air change rates. The composition and concentrations of the tested products and air samples helped identify possible emission sources, which included building sources (for formaldehyde), disinfection by-products in the laundry room, and cleaning products. VOC levels and the derived health risks in this study were at the lower range found in the US buildings. The excess lifetime cancer risk (average of 4.1 × 10⁻⁵) still indicates a need to lower exposure by reducing or removing toxic constituents, especially formaldehyde, or by increasing ventilation rates.     

Novel methods for integrated risk assessment of cumulative stressors — Results from the NoMiracle project

This special issue covers the main results of the European Sixth Framework Integrated Research project NoMiracle (Novel Methods for Risk Assessment of Cumulative stressors in Europe). New tools to analyse, characterise and quantify the combined risks to health or the environment from multiple stressors are presented or reviewed. Examples of cumulative stressors are mixtures of chemicals alone or in combination with biological or physical environmental factors such as pathogens and climate extremes. Among the main findings, the scientific work points at the importance of time in dealing with toxicity, and in particular the toxicity of chemical mixtures, the natures of the uncertainties associated with risk assessment and the value of visualisation in identifying and quantifying the most relevant risks. A major conclusion of the project is that researchers and regulators should focus on the receptor rather than on the single stressor or combination of agents. There is also a need for more efforts on mechanistic understanding and for a mechanism-based framework for interpreting mixture/multiple stressor effects.The new tools are available on the internet (http://nomiracle.jrc.ec.europa.eu).     

The Human Health Effect Programme in Greenland, a review

The burden of persistent organic pollutants (POPs) in Arctic peoples has been monitored for some years. In 1997, the Alta Declaration extended the mandate of the Arctic Assessment and Monitoring Programme (AMAP) to cover assessment of the combined effects of environmental stressors. The AMAP Phase I assessment report (Assessment report: Arctic pollution issues. Arctic monitoring and assessment programme (AMAP), Oslo Norway, xii+859 pp. Vol xii + 859 pp. Oslo, Norway, 1998) gave an overview of the classical toxicology of contaminants. Only recently a programme for measuring the potential biological effects of these contaminants has been established: The AMAP Human Health Effect Monitoring Programme. Body burden data alone are not enough to assess the health risks associated with exposure to environmental contaminants in Arctic peoples. Furthermore, laboratory studies of the effects of single chemicals or chemical mixtures in laboratory animals and cell cultures cannot fully elucidate the human health risks. Integration of epidemiological health research and effect-biomarker studies on humans from exposed populations in the Arctic is needed in order to obtain information about the real health risks resulting from exposure to the accumulated mixtures of contaminants in the Arctic. The present text aims to give a short account of background literature on known and suspected effects of environmental chemicals on endocrine regulated processes with special emphasis on Arctic conditions. Following the evaluation of existing knowledge, a survey of the recently started Human Health Effect Biomarker Programme in Greenland is given.     

A review of water quality concerns in livestock farming areas

Post-war changes in farming systems and especially the move from mixed arable-livestock farming towards greater specialisation, together with the general intensification of food production have had adverse affects on the environment. Livestock systems have largely become separated into pasture-based (cattle and sheep) and indoor systems (pigs and poultry). This paper reviews water quality issues in livestock farming areas of the UK. The increased losses of nutrients, farm effluents (particularly livestock wastes), pesticides such as sheep-dipping chemicals, bacterial and protozoan contamination of soil and water are some of the main concerns regarding water quality degradation. There has been a general uncoupling of nutrient cycles, and problems relating to nutrient loss are either short-term direct losses or long-term, related to accumulated nutrient surpluses. Results from several field studies indicate that a rational use of manure and mineral fertilisers can help reduce the pollution problems arising from livestock farming practices. Several best management practices are suggested for the control of nutrient loss and minimising release of pathogen and sheep-dip chemicals into agricultural runoff.     

Ozonation and biological activated carbon filtration of wastewater treatment plant effluents

This study investigates the fate of trace organic chemicals (TrOCs) in three full-scale reclamation plants using ozonation followed by biological activated carbon (BAC) filtration to treat wastewater treatment plant effluents. Chemical analysis was used to quantify a wide range of TrOCs and combined with bioanalytical tools to assess non-specific toxicity (Microtox assay) and estrogenicity (E-SCREEN assay). Limited dissolved organic carbon (DOC) removal (<10%) was observed in the ozonation stages showing that oxidation leads to the formation of transformation products rather than mineralization. The quantified TrOCs were removed to a degree highly dependent on the compounds’ structures and the specific ozone dose (mg_O3 mg_DOC⁻¹). Non-specific toxicity was reduced by 31-39%, demonstrating that the mixture of remaining parent compounds and their transformation products as well as newly formed oxidation by-products had an overall lower toxic potential than the mixture of parent compounds. Estrogenicity was reduced by more than 87% indicating that the transformation products of the estrogenic chemicals lost their specific toxicity potential. The subsequent BAC filtration removed between 20 and 50% of the DOC depending on the plant configuration, likely due to biodegradation of organic matter. The filtration was also able to reduce the concentrations of most of the remaining TrOCs by up to 99%, and reduce non-specific toxicity by 33-54%. Overall, the combination of ozonation and BAC filtration can achieve removals of 50% for DOC and more than 90% for a wide range of TrOCs as well as a reduction of 70% of non-specific toxicity and more than 95% of estrogenicity. This process combination is therefore suggested as an effective barrier to reduce the discharge of TrOCs into the environment or their presence in water recycling schemes.     

Macroalgal biomonitors of trace metal contamination in acid sulfate soil aquaculture ponds

Earthen shrimp aquaculture ponds are often impacted by acid sulfate soils (ASS), typically resulting in increased disease and mortality of cultured organisms. Production losses have been attributed to either low pH or to elevated concentrations of toxic metals, both direct products of pyrite oxidation in ASS. The standard farm management practice to minimise effects of pyrite oxidation is to maintain pH of pond waters above 5, based on the assumption that dissolved metal bioavailability is negligible at this pH. This study aimed to test the validity of this assumption, and therefore elucidate a possible role of toxic heavy metals in observed decreases in farm productivity. Metal bioaccumulation in four genera of macroalgae, Ulva sp., Enteromorpha sp., Cladophora sp. and Chaetomorpha sp., sampled from ASS-affected shrimp aquaculture ponds were measured using inductively coupled plasma-optical emission spectroscopy (ICP-OES) to assess the relative bioavailability of dissolved metals within the system. Results showed that all four genera of macroalgae accumulated appreciable quantities of Fe, Al, Zn, Cd, Cu, As and Pb. Iron and Al, the most common metals mobilised from ASS, were both accumulated in all algal genera to concentrations three orders of magnitude greater than all other metals analysed. These findings indicate that dissolved heavy metals are indeed bioavailable within the aquaculture pond system. A literature search of heavy metal bioaccumulation by these algal genera revealed concentrations recorded in this study are comparable to highly contaminated environments, such as those exposed to urban, industrial and mining pollution. The results of this study indicate that dissolved metal bioavailability in many earthen shrimp aquaculture ponds may be higher than previously thought.