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PubMed1995

Testing human hair for drugs of abuse. IV. Environmental cocaine contamination and washing effects.

Active cocaine use results in sequestration of parent drug in hair. In addition, hair has unique physicochemical properties that permit absorption of cocaine from the environment. When hair is tested for evidence of cocaine, it is important to consider whether the positive test resulted from active drug use or environmental contamination. In a series of laboratory experiments, it was found that exposure of 'cut' hair to cocaine vapor ('crack' smoke) and to aqueous solutions of cocaine hydrochloride resulted in significant contamination of hair samples. Similar results were obtained with two subjects who were exposed to cocaine vapor in an unventilated room. The amount of contamination adsorbed by hair depended upon both time and extent of exposure. Washing the hair samples with methanol removed > 70% of the cocaine contaminant after cocaine vapor exposure, but was less effective (< 50%) following contamination with aqueous cocaine. Shampoo treatment cycles (overnight soaking) progressively removed increasing amounts of cocaine from the contaminated hair, but residual cocaine remained after 10 cycles. Studies were also performed to determine the usefulness of benzoylecgonine as a marker of active cocaine administration. Small amounts of benzoylecgonine (ca. 1 ng/mg) were formed in hair as a result of environmental contamination with cocaine. Also, it was found that benzoylecgonine could be adsorbed from illicit cocaine contaminated with benzoylecgonine. It was concluded that positive hair test results should be interpreted cautiously due to the possibility of environmental contamination from cocaine and related constituents.

Air Pollution↗

PubMed2005

Microbial contamination of cell cultures: a 2 years study.

Cell line contamination is a major drawback of main cell banks of the world and it has cost of losing important biological products or valuable research. The causative agents are different chemicals, invertebrates, bacteria, fungi, parasites, viral species and even other cell lines. In this retrospective study, cell lines from various species such as human, fish, insect, animals either offered or accessed through usual official accession in CGBRI were studied during 2 years (2002-2004) to detect their microbial contaminations and the causative organisms. Samples were taken for sterility test upon cell lines receipt and upon each cell line sub-culture. Samples were examined for bacterial (including mycoplasmas) and fungal contamination using conventional microbiological techniques. The study excluded parasites, viruses and other contaminating agents. This study revealed 39% of specimens were contaminated. The major contaminating agents were mycoplasmas (19%) followed by mixed infection (8%), fungi (8%) and bacteria (4%). Among various bacterial species (except mycoplasmas) Bacillus sp., Enterococcus sp. and Staphylococcus sp. are main bacterial agents and among various fungi Aspergillus sp. followed by Penicillium sp., Sepedonium sp. and Botrytis sp. were main fungal causative agents of CGBRI cell line contamination. Our study also delineates each cell line contamination rate and its causative agents. This is the first report of cell culture contamination from cell banks of Middle-East countries like Iran.

Animals↗

PubMed2004

Fear of contamination.

Compulsive cleaning is an attempt to remove feelings of contamination that threaten one's physical health, mental health or ability to function socially. The fear of becoming contaminated can be complex, powerful, persistent and easily spread. Contamination is defined, the main types of contaminants set out and the characteristics of the fear are described. The distinction between normal and abnormal feelings of contamination is considered, and abnormal beliefs about contamination are analysed. Attention is drawn to the fact that contamination can occur without any physical contact, and the concept of mental pollution is used to elucidate this process. The causes and consequences of contamination fears are described, and some connections between fear and disgust are considered. The concept of cognitive co-morbidity is applied to an analysis of associations between the fear of contamination and obsessions, social fears and phobias. It is suggested that applying cognitive analyses and tactics may improve our ability to treat these powerful and tenacious fears.

Adaptation, Psychological↗

PubMed2005

Uptake of polycyclic aromatic hydrocarbons (PAHs) in salt marsh plants Spartina alterniflora grown in contaminated sediments.

Polycyclic aromatic hydrocarbon (PAH) concentrations were measured in Spartina alterniflora plants grown in pots of contaminated sediment, plants grown in native sediment at a marsh contaminated with up to 900 microg/g total PAHs, and from plants grown in uncontaminated control sediment. The roots and leaves of the plants were separated, cleaned, and analyzed for PAHs. PAH compounds were detected at up to 43 microg/g dry weight in the root tissue of plants grown in pots of contaminated soil. PAH compounds were detected at up to 0.2 microg/g in the leaves of plants grown in pots of contaminated soil. Concentrations less than 0.004 microg/g were detected in the leaves of plants grown at a reference site. Root concentration factor (RCF) values ranged from 0.009 to 0.97 in the potted plants, and from 0.004 to 0.31 at the contaminated marsh site. Stem concentration factor (SCF) values ranged from 0.00004 to 0.03 in the potted plants and 0.0002 to 0.04 at the contaminated marsh. No correlation was found between the RCF value and PAH compound or chemical properties such as logKOW. SCF values were higher for the lighter PAHs in the potted plants, but not in the plants collected from the contaminated marsh. PAH concentrations in the roots of the potted plants are strongly correlated with soil concentrations, but there is less correlation for the roots grown in natural sediments. Additional plants were grown directly in PAH-contaminated water and analyzed for alkylated PAH homologs. No difference was found in leaf PAH concentrations between plants grown in contaminated water and control plants.

Gas Chromatography-Mass Spectrometry↗

PubMed2006

Role of plant activity and contaminant speciation in aquatic plant assimilation of 2,4,5-trichlorophenol.

Aquatic plants uptake, transform and sequester organic contaminants and are used as a bioremediation strategy for the removal of pollutants from wastewaters. A better understanding of factors affecting rate of uptake of contaminants by aquatic plants is needed to improve engineered systems for removal of pollutants from wastewaters. This work focused on delineating sorption to plant surfaces and understanding effects of plant metabolic activity, inhibition, and media pH on the uptake of the ionizable contaminant 2,4,5-trichlorophenol (TCP) by aquatic plant Lemna minor. During L. minor exposure to TCP (0.5-13.9 mg l(-1)), a range of plant metabolic activities was measured using oxygen production rate (0-18.4 micromol h(-1)). A positive correlation was shown between contaminant uptake rate and plant activity. Contaminant uptake was examined at a range of media pH values (6-9) and uptake rates were linearly correlated to fraction of contaminant in protonated form. These results demonstrated a link between plant activity and uptake of contaminant by plants and stress the importance of incorporating plant metabolic activity and contaminant speciation in development of natural and engineered phytoremediation systems. This research also indicates that aquatic plants can actively accumulate trace-organic contaminants and may ultimately serve as a sink for these materials in the natural environment.

Araceae↗

PubMed2004

A review of factors affecting the release and bioavailability of contaminants during sediment disturbance events.

The factors affecting the release and bioavailability of contaminants present in sediments during natural and anthropogenic disturbance events are discussed and our current state of understanding of these processes reviewed. Published data are focused on the distribution of contaminants within undisturbed sediment, their affinities to the various solid-phase fractions of sediment and the interaction of contaminants between sediment and pore water. Sediment disturbance can lead to changes in the chemical properties of sediment that stimulate the mobilisation of contaminants. Research shows that changes in both redox potential (Eh) and pH can accelerate desorption, partitioning, bacterial degradation and the oxidation of organic contaminants. However, these processes are both sediment- and compound-specific. By affecting the affinity of contaminants to sediments, disturbance events in turn can have a significant effect on their bioavailability. Few studies have examined this phenomenon, and it is clear from the data available that there are gaps in our understanding in a number of key areas when assessing the release of contaminants from sediments: the fate of contaminants in undisturbed sediments and those that are not subjected to major disturbances, the kinetic processes that regulate metal release during changes in redox potential, the release of organometallic compounds from sediments during resuspension, the bioavailability of organic and organometallic compounds and the processes affecting contaminant release.

Animals↗

PubMed2006

Biological effects of anthropogenic contaminants in the San Francisco Estuary.

Concentrations of many anthropogenic contaminants in the San Francisco Estuary exist at levels that have been associated with biological effects elsewhere, so there is a potential for them to cause biological effects in the Estuary. The purpose of this paper is to summarize information about biological effects on the Estuary's plankton, benthos, fish, birds, and mammals, gathered since the early 1990s, focusing on key accomplishments. These studies have been conducted at all levels of biological organization (sub-cellular through communities), but have included only a small fraction of the organisms and contaminants of concern in the region. The studies summarized provide a body of evidence that some contaminants are causing biological impacts in some biological resources in the Estuary. However, no general patterns of effects were apparent in space and time, and no single contaminant was consistently related to effects among the biota considered. These conclusions reflect the difficulty in demonstrating biological effects due specifically to contamination because there is a wide range of sensitivity to contaminants among the Estuary's many organisms. Additionally, the spatial and temporal distribution of contamination in the Estuary is highly variable, and levels of contamination covary with other environmental factors, such as freshwater inflow or sediment-type. Federal and State regulatory agencies desire to develop biological criteria to protect the Estuary's biological resources. Future studies of biological effects in San Francisco Estuary should focus on the development of meaningful indicators of biological effects, and on key organism and contaminants of concern in long-term, multifaceted studies that include laboratory and field experiments to determine cause and effect to adequately inform management and regulatory decisions.

Animals↗

PubMed2004

Wound ventilation with carbon dioxide: a simple method to prevent direct airborne contamination during cardiac surgery?

Carbon dioxide (CO2) insufflation in the cardiothoracic wound cavity is used in open-heart surgery for prevention of arterial air embolism. The objective of this study was to investigate if CO2 insufflation may influence the rate of airborne contamination of the cardiothoracic wound. This was studied in a cardiothoracic wound cavity model that contained two 9 cm blood agar plates. Contamination rates were compared between a control without insufflation and insufflation with: (1) a thin open-ended tube or a gas-diffuser, (2) air or CO2, and (3) CO2 flows of 5 or 10 L/min. CO2 insufflation at 5 L/min with an open-ended tube resulted in a contamination rate almost four times that of the control (P = 0.01), whereas with the gas-diffuser the contamination rate decreased (P = 0.01). With the gas-diffuser, air insufflation at 5 L/min markedly reduced the contamination rate compared with the control (P < 0.001), but was less protective than CO2 insufflation at the same flow (P < 0.001). With both gases, the contamination rate was particularly low close to the gas-diffuser (P < 0.001). Increasing the CO2 flow from 5 to 10 L/min reduced the average contamination rate in the model from 30% to 22% (P < 0.001) of the control. At a CO2 flow of 10 L/min the contamination rate within 9 cm of the gas-diffuser was 14% of the control. Intraoperative wound ventilation with CO2 using a gas-diffuser may not only prevent air embolism, but may also significantly reduce the risk of airborne contamination and postoperative wound infection in cardiac surgery. In contrast, insufflation with an open-ended tube substantially increases these risks.

Air Microbiology↗

PubMed2006

Biological and functional responses of in situ bioassays with Chironomus riparius larvae to assess river water quality and contamination.

Single species responses have the potential to measure impacts at earlier stages than more traditional methods based in community structure. This study evaluates a bioassay with biological (survival, development, growth) and functional (post-exposure feeding rate) responses of Chironomus riparius larvae to assess water quality and contamination in rivers. The bioassay with C. riparius third instar larvae was performed, in autumn and spring, in reference sites and in organic and metal contaminated sites in Portuguese rivers. Biotic, physical and chemical parameters were determined for each site. The relationship between both bioassays responses and biotic indices (IBMWP and IASPT) and the physical and chemical parameters of respective sites were determined. In general biotic indices were able to discriminate between contaminated and not contaminated sites although they demonstrated a poor ability to detect low level of metal contamination during autumn. IASPT was negatively related to ammonia concentrations in both seasons. No significant differences in survival and post-exposure feeding rate were found between sites. Development was inhibited in the most metal contaminated site during autumn, but pH and ammonia concentrations in water accounted for 82% of developmental variation during this season. Growth was highly inhibited in the most metal contaminated site during both seasons. In autumn, growth was also inhibited in the low metal contaminated site and, during this season, pH and Mn and Fe concentrations in water samples accounted for 97% of growth variation between sites. The results suggest that in situ bioassay with C. riparius larvae using growth as the endpoint is a responsive and suitable tool that can be used as bioindicator of metal pollution and to biomonitor water quality in metal contaminated rivers.

Animals↗

PubMed2004

Environmental contaminant-mixture effects on CNS development, plasticity, and behavior.

Environmental contaminants within the polycyclic aromatic hydrocarbon (PAH) and halogenated aromatic hydrocarbon class have been shown to cross the placenta exposing the fetus to the contaminant body burden of the mother. Consequently, a gestational exposure to environmental contaminants may result in increased adverse health outcomes, possibly affecting cognitive performance. Benzo(a)pyrene [B(a)P] and 2,3,7,8, tetrachlorodibenzo-p-dioxin (TCDD) are two prototypical environmental contaminants. A systematic review of the literature suggests that there may be a relationship between vulnerability in susceptible populations and health disparities. The purpose of this mini-review is to provide a point of reference for neurotoxicological studies of environmental contaminant mixture effects on indices of development in general, and on neurodevelopment in particular. Environmental contaminant-mixture-induced decrements in (1) birth index, (2) N-methyl-D-aspartate receptor (NMDA) mRNA expression, (3) long-term potentiation (LTP), (4) fixed-ratio performance learning behavior, and (5) experience-dependent activity related cytoskeletal-associated protein (Arc) mRNA and protein expression collectively support associations between neurobehavioral deficits and gestational exposure to environmental levels of these contaminants. Collectively, data are presented in this mini-review evaluating the effect of gestational exposure to environmental contaminant-mixtures on specific indices of learning and memory, including hippocampal-based synaptic plasticity mechanisms. These indices serve as templates for learning and memory, and as such, from a vulnerability perspective, may serve as targets for dysregulation during development in susceptible populations that have been disproportionately exposed to these contaminants. Included in this review is also a discussion of the relevance of developing biomarkers for use within the framework of cumulative risk-assessment.

Animals↗

PubMed1998

Removing saliva contamination from porcelain veneers before bonding.

STATEMENT OF PROBLEM: Contamination of the fitting surfaces of porcelain veneers with saliva at the try-in stage is almost inevitable. PURPOSE: This study used bond strength tests to examine the effect of salivary contamination on Scotchbond adhesive/composite luting material bond to porcelain and evaluated the effectiveness of various procedures used (acetone, phosphoric acid) to overcome such contamination. MATERIAL AND METHODS: Bond strength test specimens were prepared with porcelain adherends. Surfaces of the adherends were cut flat, sandblasted, and divided into 12 groups, each of which received a different surface treatment. After bonding and storage for 24 hours, tensile bond strength values were measured on an Instron machine. Fracture modes were determined with a scanning electron microscope. RESULTS: Salivary contamination of porcelain surfaces significantly reduced the resin cement-to-porcelain bond from 29.2 +/- 4.5 MPa to 10.3 +/- 4.5 MPa (P <.05). Silane applied to the porcelain, a few days before contamination, resulted in increasing the bond strength from 10.3 +/- 4.5 MPa to 29.9 +/- 8.1 MPa (P <.001). The most effective method of dealing with salivary contamination was by applying silane before the try-in stage and, after the try-in, the porcelain was treated with phosphoric acid for 60 seconds and a fresh layer of silane applied. The bond strength value achieved after this method was 45.0 +/- 9.0 MPa. CONCLUSION: Contamination of porcelain surfaces with saliva is detrimental to the resin cement-to-porcelain bond. Of the many procedures investigated to overcome this contamination, the use of phosphoric acid to clean the contaminated surface was the most beneficial.

Analysis of Variance↗

PubMed2001

Integrated modelling of eutrophication and organic contaminant fate & effects in aquatic ecosystems. A review.

Eutrophication and contamination with micropollutants have been major problems in water quality management. Both problems have been subjected to extensive research and modelling but traditionally are treated separately. Traditional simulation models for aquatic systems can be categorised as eutrophication models, contaminant fate models, food web models and food chain bioaccumulation models. Because they are single issue models, many interactions and feedbacks between the food web, nutrient and toxicant cycles are missed. Linking these models is essential to evaluate the fate and risks of contaminants in systems with changing nutrient loading, to assess the natural attenuation of contaminants or to understand the selfpurifying capacity of ecosystems. Combination of the single issue models requires inclusion of 'interaction processes' to account for the coupling between the (sub-) model types, such as organic carbon cycling. toxicity, transport and accumulation of organic contaminants in the food chain, and bottom up versus top down control of primary production and nutrient cycling. This review first provides a brief overview of traditional approaches in modelling eutrophication, contaminant fate, food web dynamics and food chain bioaccumulation. Second, five existing integrated eutrophication, fate and/or effects models are reviewed. Third, the gaps and limitations in modelling the four types of interaction processes are discussed. It is concluded that these models are invaluable tools to focus attention to feedback mechanisms that are often overlooked, to identify dominating processes in ecosystems, to formulate counterintuitive hypotheses on ecosystem functioning, or to assess short term risks of acutely toxic stressors. However, the potential of integrated models for long term simulations of contaminant exposure. food chain bioaccumulation and effects to higher trophic levels remains limited, mainly because of principal limitations in food web modelling. In contrast, the potential of integrated models for long term simulations of contaminant fate is better because the environmental distribution of contaminants is mainly determined by the major abiotic compartments and by biotic compartments at the base of the food chain.

Animals↗

PubMed2002

Simultaneous uptake of anionic surfactants and micellar-solubilized contaminants using anion-exchange resins.

This research studied simultaneous uptake of anionic surfactants and micellar-solubilized organic contaminants by anion-exchange resins. Anionic surfactant molecules adsorbed onto the positively charged resin mainly through electrostatic attraction, while the micellar-solubilized contaminants were excluded from aqueous solutions once the remaining micelles could no longer solubilize them. Data suggest that the excess contaminants adsorbed onto the resin skeleton and admicelle layer formed on the resin surface through hydrophobic interactions and eventually partitioned into the resin gel phase matrix. In batch adsorption, the contaminant solubilization capacity did not decrease linearly with respect to surfactant concentration decrease due to the increased solution counterion activity during anion exchange, and caused "delayed" contaminant uptake relative to that of the surfactant. No such effect occurred in continuous column adsorption, where the surfactant and contaminant breakthrough occurred simultaneously. Surfactant head and tail group properties, along with resin structure and particle size significantly affected surfactant and contaminant uptake rates. Relative to recovering the surfactant, the high exchange potential of the anionic surfactant prevented effective surfactant desorption, even at high electrolyte concentration and in the presence of a cosolvent. The resin matrix also had high affinity for the partitioned contaminant, and the contaminant elution from the resin seemed to be controlled by equilibrium partitioning.

Adsorption↗

PubMed2003

Total mercury concentrations in an industrialized catchment, the Thur River basin (north-eastern France): geochemical background level and contamination factors.

River bottom sediments and soils were collected from the industrialized Thur River basin (north-eastern France) to assess mercury contamination. The regional geochemical background level of total mercury was evaluated to calculate mercury contamination factors (Fc) in soils and river bottom sediments. Our estimate of the mean background mercury levels in river sediments and soils, not affected by human activities, was 232 ng x g(-1) (range: 27-406 ng x g(-1)). Sediments contaminated by the effluent from a chlor-alkali plant yielded the highest contamination factors (Fc=1784). Contamination factors of surficial soils within 1 km of the industrial site range from 6.3 to 43.6. This contamination is attributed to diffuse atmospheric deposition from this local plant. However, even upstream from this industrial area elevated contamination factors were recorded for river bottom sediments (Fc=3.2 to 26.4) and for one alluvial soil profile (Fc=10). This is possibly due to past pollution resulting from waste water discharges. Mercury contamination in the different horizons of alluvial soils is not correlated with soil organic carbon content, but may be the result of occasional accidental pollution arising from the introduction of contaminated suspended particulate matter by the Thur River during periods of flooding.

Aluminum↗

PubMed1997

Organochlorine contaminants in blubber of four seal species: integrating biomonitoring and specimen banking.

Blubber samples from four Alaska seal species (bearded seal, Erignathus barbatus, harbor seal, Phoca vitulina, northern fur seal, Callorhinus ursinus, ringed seal, P. hispida) were collected for inclusion in the US National Biomonitoring Specimen Bank, as well as for immediate analysis as part of the contaminant monitoring component of the US National Marine Fisheries Service's Marine Mammal Health and Stranding Response Program. The blubber samples were analyzed for organochlorine (OC) contaminants (e.g., PCB congeners, pesticides, DDTs). Results for bearded and ringed seals from the Alaska Arctic revealed low blubber concentrations of OC contaminants. Harbor seals from Prince William Sound. Gulf of Alaska, had somewhat higher blubber concentrations of OC contaminants. In contrast, northern fur seals sampled from the Pribilof Islands had blubber concentrations of certain OC contaminants that were about an order of magnitude higher than those found in the other seal species. Differences in contaminant concentrations among the Alaska seals may be explained by differences in feeding habits and migratory patterns, age or gender did not appear to account for the differences observed. The highest concentrations of OCs were found in harbor seals stranded along the northwestern US mainland, which is consistent with higher concentrations of anthropogenic contaminants being found in urban coastal areas than in more remote Arctic environments. The integration of real-time contaminant monitoring with specimen banking provides important baseline data that can be used to plan and manage banking activities. This includes identifying appropriate specimens that are useful in assessing temporal trends and increasing the utility of the banked samples in assessing chemical contaminant accumulation and relationships to biological effects.

Adipose Tissue↗

PubMed2002

Arsenic contamination of the environment: a new perspective from central-east India.

This paper reports a regional contamination of the environment in central-east India that does not share geology or boundary with the Bengal Delta Plain. About 30,000 people residing in 30 villages and towns are directly exposed to arsenic and more than 200,000 people are "at risk." Complete geographical extent of this contamination is being established, and this newly reported contaminated area could be quite large. This paper further reports that the mechanisms involved in arsenic mobilisation are complex and the two theories of arsenic mobilisation, i.e., pyrite oxidation and oxyhydroxides reduction, do not fully explain the high levels of arsenic contamination. This paper also proposes the "oxidation-reduction theory" for arsenic mobilisation where the arsenic originates from the arsenopyrite oxidation and the arsenic thus mobilised forms the minerals and gets reduced underground in favourable Eh conditions. The stoppage of water withdrawal from the contaminated sources did not result in lowering of arsenic levels as expected according to the heavy groundwater extraction theory (pyrite oxidation theory). Cases of arsenicosis in the region are on the rise and the switchover to less contaminated water has not reversed the arsenicosis progression in the affected persons even after 2 years. Surface water of the rivers is also being contaminated because of the probable dislocation of contaminated groundwater due to the heavy rains in monsoon season, which indicates that the river water could be a major carrier of arsenic in dissolved or adsorbed forms that may be a cause of contamination of the delta plains.

Arsenic↗

PubMed2003

Metal concentrations in mussel Crenomytilus grayanus and oyster Crassostrea gigas in relation to contamination of ambient sediments.

The relationship between Zn, Cu, Cd, Pb, and Ni concentrations in soft tissues of mussels and oysters and those in ambient sediments was examined. The study area was the coastal habitats of the northwestern Sea of Japan, which has a broad range of contamination due to urban sewage. Significant increases of all metals, except Ni, were observed in mussel Crenomytilus grayanus at concentrations of easily leachable metals in ambient sediments higher than 2, 100, and 800 microg/g for Cd, Cu, and Zn, respectively. Pb was accumulated by the mussels with no distinct threshold in Pb contamination of sediments. After 2 months, C. grayanus transplanted from a pristine to a contaminated locality increased in Pb up to 12%, and Cu up to 68% of concentrations of these metals in the contaminated local mussels, but Zn and Cd concentrations increased only in the excretory tissue, not in the somatic tissue, or in the soft tissue as a whole. Such regulation of metal accumulation puts limitations on the use of C. grayanus for monitoring of slightly and moderately contaminated localities. On the other hand, the oyster Crassostrea gigas showed definite accumulation of all metals, except Ni, at moderate contamination of ambient sediments. As contamination of sediments increased, increases of Pb, Zn and Cu concentrations in C. gigas slowed, possibly due to physiological control at very high metal concentrations in oyster soft tissue. Thus, the mussel C. grayanus should be used mainly for the monitoring of heavy contaminated localities, and the oyster C. gigas is more suitable as an indicator of low and moderate contamination.

Animals↗

PubMed2001

Zero-tolerance for faecal contamination of carcasses as a tool in the control of O157 VTEC infections.

The Dutch government, the meat producers organisation and the meat industry have recognised O157 VTEC as an important public health hazard, and agreed on the necessity to improve the hygiene in Dutch cattle- and calf-slaughtering establishments. This paper reports activities within a national action programme to achieve this objective, "Zero-tolerance for faecal contamination during slaughter of cattle and calves". The study included inspection of hygienic performances in slaughterhouses, and visual and microbiological (aerobic plate counts, Enterobacteriaceae counts and O157 VTEC presence/absence on visually clean cattle and calf carcasses) assessment of carcass cleanliness. Initial studies concluded that the hygienic performances in the Dutch cattle and calf slaughterhouses should be immediately improved. In 52% of the slaughterhouses inspected, carcasses were observed to be contaminated with hide, hair or faeces. Around 45% of the slaughterhouses had constructural deficiencies likely to lead to structural cross-contamination of carcasses, by direct carcass-carcass contact, or by indirect contacts with floors, walls or steps. In 39% of the slaughterhouses, cleaning and disinfection procedures were inadequate. Visual inspection of chilled carcasses found that in 11 of the 27 slaughterhouses visited, more than 10% of the carcasses were visibly contaminated. In 6 of the 27 slaughterhouses visited, more than 50% of the carcasses inspected were visibly contaminated. Microbiological analysis of visually clean carcasses noted contamination levels similar to those reported from other countries. O157 VTEC were not isolated during this study. Circulation of these findings lead to increased efforts by all parties to fulfil the requirements of the statutory "Zero-tolerance" programme. A follow-up study noted a significant decrease in the proportions of faecally contaminated carcasses, i.e., 7% of chilled carcasses were visibly contaminated with faeces, as opposed to 22% contamination during the initial study. The follow-up study also noted a greater awareness of the importance of good hygienic practices among slaughterhouse personnel and government meat inspectors.

Abattoirs↗