Patient engagement with radiation therapists: Patient perspectives, challenges, and opportunities. A systematic review.

INTRODUCTION: Radiotherapy is a major component of cancer care and treatment is delivered almost exclusively by therapeutic radiographers/radiation therapists (RTTs). Numerous government and professional guidance publications have recommended a person-centred approach to healthcare through communication and collaboration between professionals, agencies, and users. With approximately half of patients undergoing radical radiotherapy experiencing some degree of anxiety and distress, RTTs are uniquely placed as frontline cancer professionals to engage with patients regarding their experience. This review seeks to map the available evidence of patient reported views of their experience of being treated by RTTs and any impact, this treatment had on the patient's frame of mind or perception of treatment. METHODS: In line with the principles of the Preferred Reporting Items for Systematic and Meta-Analyses (PRISMA) systematic review methodology, a review of relevant literature was conducted. Electronic databases MEDLINE, PROQUEST, EMBASE and CINAHL were searched. RESULTS: Nine hundred and eighty-eight articles were identified. Twelve papers were included in the final review. CONCLUSION: Increased time with, and continuity of RTTs during treatment has a positive influence on patients' perspectives of RTTs. A positive patient perspective of their engagement with RTTs can be a strong predictor of overall satisfaction in radiotherapy. IMPLICATIONS FOR PRACTICE: RTTs should not underestimate the impact of their supportive role in guiding patients through treatment. A standardised method for integrating patients' experience and engagement with RTTs is lacking. Further RTT led research is required in this area.

Patient-reported perspectives of therapeutic radiographers when undergoing radiotherapy: A European multi-centre study.

INTRODUCTION: Radiotherapy is delivered almost exclusively by therapeutic radiographers/radiation therapist (RTTs). Patient's perspectives of RTTs affect levels of trust and confidence in the profession and can have a significant impact on overall radiotherapy experience. The study reports patients' perspectives of RTTs from their experience of undergoing radiotherapy. Four partner sites collaborated in this research and included Malta, Poland, Portugal, and the UK (lead site). METHODS: A survey was developed to gather information from patients receiving radiotherapy or who had had radiotherapy within the previous 24 months. Participants ranked their responses to 23 statements relating to person-centred care on a 5-point scale of 1 (strongly disagree) to 5 (strongly agree). Mann-Whitney or Kruskal Wallis tests were applied to test differences in responses to 5 key statements for patient characteristics including gender, age group, diagnosis, country, time spent with RTTs and number of fractions remaining at survey completion. RESULTS: Three hundred and forty-seven surveys are included. Patients report a positive perception of RTTs (95.4% agree with 'I feel cared for'). Statistically significant differences in responses were found between gender, diagnosis, country, time spent with RTTs and fractions of radiotherapy remaining. Patients who had more time with RTTs and completed their surveys during radiotherapy had a more positive perception of RTTs. CONCLUSION: This study suggests that sufficient time with RTTs is key to ensuring a positive radiotherapy patient experience. RTTs being attentive, understanding, and informative are most predictive of a positive overall patient experience. Timing of survey completion can influence responses. IMPLICATIONS FOR PRACTICE: RTT education programmes should incorporate training on person-centred care at all levels. Further research into patient experience of RTTs is warranted.

Patients' perspectives of the skills and competencies of therapy radiographers/radiation therapists (TRs/RTTs) in the UK, Portugal and Malta; a qualitative study from the SAFE Europe project.

INTRODUCTION: The role of the Therapy Radiographer/Radiation Therapist (TR/RTT) is to provide radiotherapy to patients with a cancer diagnosis. This includes, not only administration of treatment, but also management of side-effects and provision of support/care. Despite this role being consistent throughout Europe, there is currently no standardisation of education for TRs/RTTs. The SAFE EUROPE project aims to standardize TR/RTT education to enable 'safe and free exchange' of TRs/RTTs across Europe. Consequently, this study aims to explore patients' perspectives regarding the current skills and competencies of TRs/RTTs. METHODS: From May 2021 to February 2022, semi-structured interviews were conducted with patients who had recently received radiotherapy in the UK, Malta and Portugal. Ethical approval for this study was granted by the NHS Research Ethics Committee with additional local approvals obtained. RESULTS: Forty-eight participants from the UK (n = 18), Portugal (n = 19), and Malta (n = 11) completed interviews. Participants described high satisfaction with TRs'/RTTs' competence and skills in all three countries. The main theme arising from the analysis was the importance of trust building with TRs/RTTs. Six factors were identified as influencing levels of trust: communication; side-effect management; team consistency; relational skills; patient dignity; and competence. A small number of patients reported feeling rushed and not having their physical and emotional needs met by TRs/RTTs. CONCLUSION: This multicentre study demonstrated that patients perceive TRs/RTTs in the UK, Malta and Portugal as highly competent and skilled. Practical recommendations are provided to address identified deficits in practice, which can be addressed through adaptation of TR/RTT education/training and clinical practice. IMPLICATIONS FOR PRACTICE: Recommendations arising from this study are important to ensure that TRs/RTTs have transferable skills that provide consistently high quality care to patients throughout Europe.

An investigation of digital skills of therapeutic radiographers/radiation therapists: A european survey of proficiency level and future educational needs.

INTRODUCTION: This study aims to assess the proficiency level of digital skills, the factors influencing that level and the training needs of Therapeutic Radiographers/Radiation Therapists (TR/RTTs), due to the differences in technology availability and accessibility, variations in the regulation and education of TR/RTTs in European countries, and the lack of a digital skills framework. METHODS: An online survey was distributed to TR/RTTs working in Europe to capture their self-assessment of proficiency levels of digital skills when performing their clinical role. Information was also gathered regarding training, work experience and level of information and communication technology (ICT) skills. Quantitative measures were analysed using descriptive statistics and correlation between variables, and qualitative responses using thematic analysis. RESULTS: 101 respondents from 13 European countries completed the survey. Digital skills in treatment planning followed by management and research were the least developed skills, while the most developed were transversal digital skills followed by digital skills in treatment delivery. The Radiotherapy areas of practice where TR/RTT has experience (e.g. Planning Image, Treatment Planning, Treatment), as well as the level of generic ICT skills (communication, content creation and problem-solving), was related to the level of proficiency of TR/RTT digital skills. Greater scope of practice and level of generic ICT were associated with a higher level of TR/RTT digital skills. Thematic analysis allowed the identification of new sub-themes to be included in the training of TR/RTTs. CONCLUSION: Education and training of TR/RTTs should be improved and adapted to the current needs of digitalisation to avoid differences in digital proficiency levels. IMPLICATIONS FOR PRACTICE: Aligning TR/RTTs' digital skill sets with emerging digitalisation will improve current practice and ensure the best care to all RT patients.

An evaluation of knowledge of circular economy among Therapeutic Radiographers/Radiation Therapists (TR/RTTs): Results of a European survey to inform curriculum design.

INTRODUCTION: Global warming and the increase in greenhouse gases are a current concern worldwide. The healthcare sector constitutes about 4.4% of all emissions. This study aims to evaluate the knowledge, awareness and attitudes of Therapeutic Radiographers/Radiation Therapists (TR/RTTs) regarding environment-related concepts to inform the development of educational curriculum. METHODS: A validated self-designed survey was distributed to TR/RTTs across Europe by the SAFE EUROPE partners and via social media between October 2021 and February 2022. The survey was divided into six sections: (i) demographics, (ii) knowledge of Circular Economy (CE) and Green Skills (GS), (iii) personal attitudes, (iv) TR/RTTs attitudes, (v) the importance of CE, and (vi) education. Questions consisted of mostly Likert scales complemented with other closed- and open-ended questions. RESULTS: 31%-42% of participants are aware of national and departmental policies in CE and GS concepts. Even though half of the participants considered that they advocate and practice CE, the open questions indicated that participants only focus on waste management, ignoring all the other dimensions of CE in healthcare. Personal attitudes and lifestyles also did not reflect CE. TR/RTTs considered CE practices and GS development essential. However, the suggested academic level at which these skills should be developed was split between High School (44%) and Bachelor's degree (32%). CONCLUSION: It is essential to raise awareness among TR/RTTs about the various dimensions of CE applied to healthcare: "green transportation", "environment-friendly procurement", "hospital building design", "food process optimisation", "water reduction", "energy efficiency", and "waste management". IMPLICATIONS FOR PRACTICE: These GS must be developed by TR/RTTs to decrease their impact on the environment. Their training may need to be lifelong, starting during basic high school education and continuing as healthcare professionals after graduation.

Digital skills of therapeutic radiographers/radiation therapists - Document analysis for a European educational curriculum.

INTRODUCTION: It is estimated that around 50% of cancer patients require Radiotherapy (RT) at some point during their treatment, hence Therapeutic Radiographers/Radiation Therapists (TR/RTTs) have a key role to play in patient management. It is essential for TR/RTTs to keep abreast with new technologies and continuously develop the digital skills necessary for safe RT practice. The RT profession and education is not regulated at European Union level, which leads to heterogeneity in the skills developed and practised among countries. This study aimed to explore the white and grey literature to collate data on the relevant digital skills required for TR/RTTs practice. METHODS: An exhaustive systematic search was conducted to identify literature discussing digital skills of TR/RTTs; relevant grey literature was also identified. A thematic analysis was performed to identify and organise these skills into themes and sub-themes. RESULTS: 195 digital skills were identified, organised in 35 sub-themes and grouped into six main themes: (i) Transversal Digital Skills, (ii) RT Planning Image, (iii) RT Treatment Planning, (iv) RT Treatment Administration, (v) Quality, Safety and Risk Management, and (vi) Management, Education and Research. CONCLUSION: This list can be used as a reference to close current gaps in knowledge or skills of TR/RTTs while anticipating future needs regarding the rapid development of new technologies (such as Artificial Intelligence or Big Data). IMPLICATIONS FOR PRACTICE: It is imperative to align education with current and future RT practice to ensure that all RT patients receive the best care. Filling the gaps in TR/RTTs skill sets will improve current practice and provide TR/RTTs with the support needed to develop more advanced skills.

Competency level in radiotherapy across EU educational programmes: A cross-case study evaluating stakeholders' perceptions.

INTRODUCTION: The education of Therapeutic Radiographers (TRs) is regulated in some countries but is not standardised across the EU, leading to differences in competencies between and within member states. This study aimed to explore stakeholders' perceptions regarding underdeveloped competencies of TRs practising on the linear accelerator, identified in a previous study by the same research team. METHODS: Interviews with stakeholders from four countries (selected based on the characteristics of their degrees) were performed as part of this cross-case study. Stakeholders were asked to provide their perception regarding the least developed competencies identified in a previous study. RESULTS: The 27 stakeholders confirmed that Pharmacology, Quality Assurance (QA), Management and Leadership, Research (from the previous study) were underdeveloped and identified Image Verification and Critical Thinking as additional underdeveloped competencies. Suggested causes included: lack of regulation of required competencies at the national level, lack of training dedicated to radiotherapy (RT) (taught within generic modules) and lack of time within the degree programme. The ideal academic level to develop these competencies and whether they are essential varied between country and stakeholder. CONCLUSION: It is essential to regulate learning outcomes at the national level to ensure a high level of care is provided to all RT patients and, ideally, standardise it across Europe. Education institutions should review their curricula to ensure that sufficient time is dedicated to RT and that the essential competencies are developed. Due to time constraints within some programmes, some competencies must be developed after graduation. IMPLICATIONS FOR PRACTICE: Lack of regulation of learning outcomes (at European level and national level in many countries) and lack of RT-specific training lead to underdeveloped competencies that may compromise patient care.

Chemical interactions and mixtures in public health risk assessment: An analysis of ATSDR's interaction profile database.

The Agency for Toxic Substances and Disease Registry (ATSDR) develops interaction profiles using binary weight of evidence (BINWOE) methodology to determine interaction directions of common environmental mixtures. We collected direction of interactions, BINWOE score determination, and BINWOE score confidence rating from 13 interaction profiles along with toxicodynamic and toxicokinetic influences on interaction direction. By doing so, we quantified the 1) direction of interaction and indeterminate evaluations; 2) characterized confidence in the BINWOE determinations; and 3) quantified toxicokinetic/toxicodynamic, and other influences on projected BINWOE interaction directions. Thirty-nine percent (130/336) of the attempts to make a BINWOE were indeterminate due to no interaction data or inadequate or conflicting evidence. Out of remaining BINWOEs, 25% were additive, 9% were greater-than-additive, and 27% were less-than-additive interactions. Fifty-five percent of BINWOEs were explained by toxicokinetic interactions, 12% and 5% were explained by toxicodynamic and other explanations, respectively. High quality mixture toxicology in vivo studies along with mixture in vitro and in silico studies will lead to greater confidence in interaction directions and influences. Limitations for interpretation of the data were also included.

Evaluation of radiotherapy education across the EU and the impact on graduates' competencies working on the linear accelerator.

INTRODUCTION: Regulation and education of the professionals administering radiotherapy treatments in the linear accelerator varies across the EU. However, how different programme characteristics affect the level of competency of these professionals has never been studied before. This study also aimed to assess which are the least and most developed competencies in radiotherapy across the EU. METHODS: An online questionnaire was distributed to academic staff teaching radiotherapy across the EU. Staff were asked to identify the characteristics of the course programmes and to classify the level of competency of graduates regarding linear accelerator tasks. RESULTS: Fifty respondents from 19 EU countries answered the questionnaire. The least developed competency theme was pharmacology followed by equipment quality assurance and management and leadership. The most developed competency was positioning and immobilisation, followed by radiotherapy treatment delivery and professional and ethical practice. Some competencies are developed at the same level across EU countries, while others vary considerably between member-states. Longer programmes, with more placements, and larger proportions of radiotherapy in the programme showed significant increase in the development of some competencies. Longer placements in skills labs was correlated with a decrease in competency. CONCLUSION: There is no harmonisation of radiotherapy eduction across the EU and the differences in programme characteristics are reflected in differences in competency levels of radiotherapy radiographers. This may hinder movement of professionals and create disparities in the level of care offered across the EU. IMPLICATIONS FOR PRACTICE: Longer programmes, with longer clinical practice and adequate proportion of radiotherapy in the course are essential to ensure that these professionals are competent at similar levels across the EU and to ensure patient safety.

Competencies of therapeutic radiographers working in the linear accelerator across Europe: A systematic search of the literature and thematic analysis.

INTRODUCTION: The literature identifies various competences required for therapy radiographers (TR), however, these are varied and scattered among different publications. The aim of this study was to identify the competences required by therapy radiographers practising on the linear accelerator in the European setting, according to published literature. METHODS: A systematic approach was performed to find relevant literature. The literature was then scrutinised for competences practised by linac TRs. Thematic analysis was performed to organise the competences according to themes. RESULTS: A list of 170 competences were generated based on the assessment of 28 publications. The competences were organised in themes, including "delivery of treatment", "verification of patient setup", "patient care" and "teamwork and multidisciplinarity". The competences of the therapeutic radiographers encompass multiple themes, evidence of the complexity of the role of these professionals. CONCLUSION: Radiographers across Europe must be trained to the highest standards to ensure the best care possible is given to patients, irrespective of the country the radiographer trained in. This will also promote for free movement of professionals across countries. The competences identified can be used as reference for the design of academic curriculum for TRs practising across Europe.

An evaluation of the educational requirements to practise radiography in the European Union.

INTRODUCTION: Radiography is practised world wide, however, the definition of the profession varies across countries. As there is no regulation of the profession or education at EU level, different national regulations might result in educational differences that can compromise the movement of professionals or the safety of patients. The aim of this study was to identify the commonalities and discrepancies in national regulation of radiography. METHODS: National competent authorities from all EU countries where the profession is regulated (n = 27) were invited to identify the legal requirements to practise radiography and the data was analysed using thematic analysis. RESULTS: One country does not regulate the profession in the EU. Although, a single profession is regulated in 83% of the cases, 21% regulate separate professions for different specialisms (diagnostic radiography, radiotherapy and nuclear medicine). All countries (n = 27) define education as requirement to practise, however, the academic level varies from secondary school to Master's degree with required programmes varying from 2 to 4 years and from 120 to 240 ECTS. In addition, the subjects covered in the education programme showed great heterogeneity. These subjects were not identified by 35% of the respondents (n = 23) and only 26% define the subjects in terms of competencies. CONCLUSION: Education is a requisite to practise all over the EU, however, the lack of EU-wide regulation leads to a variation of national regulations. These differences may lead to inhomogeneity of competencies being developed, compromising the movement of professionals across Europe and patient safety.

Integrating the Forensic Sciences in Wildlife Case Investigations: A Case Report of Pentobarbital and Phenytoin Toxicosis in a Bald Eagle (Haliaeetus leucocephalus).

The application of medical knowledge to the purpose of law is the foundation of forensic pathology. A forensic postmortem examination often involves the expertise of multiple scientific disciplines to reconstruct the full story surrounding the death of an animal. Wildlife poses additional challenges in forensic investigations due to little or no associated history, and the disruptive effects of decomposition. To illustrate the multidisciplinary nature of wildlife forensic medicine, the authors outline a case of secondary pentobarbital/phenytoin toxicosis in a bald eagle (Haliaeetus leucocephalus). The eagle was the single fatality in a group of 8 birds that fed on euthanized domestic cat remains that had been improperly disposed of in a landfill. Cooperation between responding law enforcement officers, pathologists, and other forensic scientists led to the successful diagnosis and resolution of the case.

Bacillus cereus in personal care products: risk to consumers.

Bacillus cereus is ubiquitous in nature and thus occurs naturally in a wide range of raw materials and foodstuffs. B. cereus spores are resistant to desiccation and heat and able to survive dry storage and cooking. Vegetative cells produce several toxins which on ingestion in sufficient numbers can cause vomiting and/or diarrhoea depending on the toxins produced. Gastrointestinal disease is commonly associated with reheated or inadequately cooked foods. In addition to being a rare cause of several acute infections (e.g. pneumonia and septicaemia), B. cereus can also cause localized infection of post-surgical or trauma wounds and is a rare but significant pathogen of the eye where it may result in severe endophthalmitis often leading to loss of vision. Key risk factors in such cases are trauma to the eye and retained contaminated intraocular foreign bodies. In addition, rare cases of B. cereus-associated keratitis (inflammation of the cornea) have been linked to contact lens use. Bacillus cereus is therefore a microbial contaminant that could adversely affect product safety of cosmetic and facial toiletries and pose a threat to the user if other key risk factors are also present. The infective dose in the human eye is unknown, but as few as 100 cfu has been reported to initiate infection in a susceptible animal model. However, we are not aware of any reports in the literature of B. cereus infections in any body site linked with use of personal care products. Low levels of B. cereus spores may on occasion be present in near-eye cosmetics, and these products have been used by consumers for many years. In addition, exposure to B. cereus is more likely to occur through other routes (e.g. dustborne contamination) due to its ubiquity and resistance properties of spores. The organism has been recovered from the eyes of healthy individuals. Therefore, although there may be a perceived hazard, the risk of severe eye infections as a consequence of exposure through contaminated near-eye cosmetics is judged to be vanishingly small. It is unlikely that more stringent microbiological standards for near-eye cosmetics will have any impact on the risk of severe eye infections caused by B. cereus, as these are not linked to use of personal care products.

Applications of omics approaches to the development of microbiological risk assessment using RNA virus dose-response models as a case study.

The last decade has seen a huge increase in the amount of 'omics' data available and in our ability to interpret those data. The aim of this paper was to consider how omics techniques can be used to improve and refine microbiological risk assessment, using dose-response models for RNA viruses, with particular reference to norovirus through the oral route as the case study. The dose-response model for initial infection in the gastrointestinal tract is broken down into the component steps at the molecular level and the feasibility of assigning probabilities to each step assessed. The molecular mechanisms are not sufficiently well understood at present to enable quantitative estimation of probabilities on the basis of omics data. At present, the great strength of gene sequence data appears to be in giving information on the distribution and proportion of susceptible genotypes (for example due to the presence of the appropriate pathogen-binding receptor) in the host population rather than in predicting specificities from the amino acid sequences concurrently obtained. The nature of the mutant spectrum in RNA viruses greatly complicates the application of omics approaches to the development of mechanistic dose-response models and prevents prediction of risks of disease progression (given infection has occurred) at the level of the individual host. However, molecular markers in the host and virus may enable more broad predictions to be made about the consequences of exposure in a population. In an alternative approach, comparing the results of deep sequencing of RNA viruses in the faeces/vomitus from donor humans with those from their infected recipients may enable direct estimates of the average probability of infection per virion to be made.

The effect of cationic microbicide exposure against Burkholderia cepacia complex (Bcc); the use of Burkholderia lata strain 383 as a model bacterium.

AIM: The extensive use of microbicides in a wide range of applications has been questioned with regard to their role in the development of bacterial resistance to antimicrobials. This study aims to measure the phenotypic and genotypic changes in Burkholderia lata strain 383 exposed to chlorhexidine gluconate (CHG) and benzalkonium chloride (BZC), two commonly used cationic microbicides. METHODS AND RESULTS: The susceptibility of B. lata strain 383 to CHG and BZC and a range of antibiotics was determined using standardized MIC, MBC and antibiotic susceptibility testing protocols before and after short-term exposure to a low microbicide concentration. Measurements were performed on four separate occasions over a 1-year period. Changes in gene expression were investigated using quantitative real-time PCR. Although the susceptibility profile to CHG and BZC was not altered, a change in antibiotic susceptibility profile was observed for ceftazidime, and for imipenem and ciprofloxacin in 2/4 repeats. An outer membrane protein and ABC transporter were found to be significantly upregulated following treatment with BZC and CHG, respectively. CONCLUSIONS: The comparison of MIC and MBC results following microbicide exposure with baseline data offered a prospective protocol to quantify any change in bacterial susceptibility profile. However, the use of a standardized antibiotic susceptibility protocol with B. lata strain 383 showed some inconsistencies in results between repeats. SIGNIFICANCE AND IMPACT OF THE STUDY: With ever-increasing interest in the impact of microbicides on emerging antimicrobial resistance in bacteria growing, this study demonstrated that comparing susceptibility profile obtained after exposure to microbicides with baseline susceptibility values could play a role in establishing the potential risk of microbicide resistance and cross-resistance development and also in the development of a protocol that allows the prediction of microbicide resistance.

A risk assessment approach for fresh fruits.

AIMS: To describe the approach used in conducting a fit-for-purpose risk assessment of microbiological human pathogens associated with fresh fruit and the risk management recommendations made. METHODS AND RESULTS: A qualitative risk assessment for microbiological hazards in fresh fruit was carried out based on the Codex Alimentarius (Codex) framework, modified to consider multiple hazards and all fresh (whole) fruits. The assessment determines 14 significant bacterial, viral, protozoal and nematodal hazards associated with fresh produce, assesses the probable level of exposure from fresh fruit, concludes on the risk from each hazard, and considers and recommends risk management actions. A review of potential risk management options allowed the comparison of effectiveness with the potential exposure to each hazard. CONCLUSIONS: Washing to a recommended protocol is an appropriate risk management action for the vast majority of consumption events, particularly when good agricultural and hygienic practices are followed and with the addition of refrigerated storage for low acid fruit. Additional safeguards are recommended for aggregate fruits with respect to the risk from protozoa. SIGNIFICANCE AND IMPACT OF THE STUDY: The potentially complex process of assessing the risks of multiple hazards in multiple but similar commodities can be simplified in a qualitative assessment approach that employs the Codex methodology.

Measurement of p-nitrophenol in the urine of residents whose homes were contaminated with methyl parathion.

During the last several years, illegal commercial application of methyl parathion (MP) in domestic settings in several U.S. Southeastern and Midwestern States has affected largely inner-city residents. As part of a multiagency response involving the U.S. Environmental Protection Agency (U.S. EPA), the Agency for Toxic Substances and Disease Registry (ATSDR), and state and local health departments, our laboratory developed a rapid, high-throughput, selective method for quantifying p-nitrophenol (PNP), a biomarker of MP exposure, using isotope dilution high-performance liquid chromatography-tandem mass spectrometry. We measured PNP in approximately 16,000 samples collected from residents of seven different states. Using this method, we were able to receive sample batches from each state; prepare, analyze, and quantify the samples for PNP; verify the results; and report the data to the health departments and ATSDR in about 48 hr. These data indicate that many residents had urinary PNP concentrations well in excess of those of the general U.S. population. In fact, their urinary PNP concentrations were more consistent with those seen in occupational settings or in poisoning cases. Although these data, when coupled with other MP metabolite data, suggest that many residents with the highest concentrations of urinary PNP had significant exposure to MP, they do not unequivocally rule out exposure to PNP resulting from environmental degradation of MP. Even with their limitations, these data were used with the assumption that all PNP was derived from MP exposure, which enabled the U.S. EPA and ATSDR to develop a comprehensive, biologically driven response that was protective of human health, especially susceptible populations, and included clinical evaluations, outreach activities, community education, integrated pest management, and decontamination of homes.

Removal of volatile and semivolatile organic contamination from soil by air and steam flushing.

A soil core, obtained from a contaminated field site, contaminated with a mixture of volatile and semivolatile organic compounds (VOC and SVOC) was subjected to air and steam flushing. Removal rates of volatile and semivolatile organic compounds were monitored during flushing. Air flushing removed a significant portion of the VOC present in the soil, but a significant decline in removal rate occurred due to decreasing VOC concentrations in the soil gas phase. Application of steam flushing after air flushing produced a significant increase in contaminant removal rate for the first 4 to 5 pore volumes of steam condensate. Subsequently, contaminant concentrations decreased slowly with additional pore volumes of steam flushing. The passage of a steam volume corresponding to 11 pore volumes of steam condensate reduced the total VOC concentration in the soil gas (at 20 degrees C) by a factor of 20 to 0.07 mg/l. The corresponding total SVOC concentration in the condensate declined from 11 to 3 mg/l. Declines in contaminant removal rates during both air and steam flushing indicated rate-limited removal consistent with the persistence of a residual organic phase, rate-limited desorption, or channeling. Pressure gradients were much higher for steam flushing than for air flushing. The magnitude of the pressure gradients encountered during steam flushing for this soil indicates that, in addition to rate-limited contaminant removal, the soil permeability (2.1 x 10(-9) cm2) would be a limiting factor in the effectiveness of steam flushing.