Efficacy of three anti-malarial regimens for uncomplicated Plasmodium falciparum malaria in Cambodia, 2009-2011: a randomized controlled trial and brief review

BACKGROUND

Anti-malarial resistance remains an important public health challenge in Cambodia. The effectiveness of three therapies for uncomplicated falciparum malaria was evaluated in Oddar Meanchey province in Northern Cambodia from 2009 to 2011.

METHODS

In this randomized, open-label, parallel group-controlled trial, 211 subjects at least 5 years old with uncomplicated falciparum malaria were treated with 3 days of directly observed therapy: 63 received artesunate-mefloquine (AS/MQ), 77 received dihydroartemisinin-piperaquine (DHA/PPQ), and 71 received atovaquone-proguanil (ATQ/PG). The subjects were followed for 42 days or until recurrent parasitaemia. Genotyping of msp1, msp2, and glurp among individual parasite isolates distinguished recrudescence from reinfection. Pfmdr1 copy number was measured by real-time PCR and half-maximal parasite inhibitory concentrations (IC50) were measured in vitro by 48-h isotopic hypoxanthine incorporation assay.

RESULTS

The per-protocol PCR-adjusted efficacy (95% confidence interval) at 42 days was 80.6% (70.8-90.5%) for AS/MQ, 97.2% (93.3-100%) for DHA/PPQ, and 92.9% (86.1-99.6%) for ATQ/PG. On day 3, 57.9% remained parasitaemic in the AS/MQ and DHA/PPQ arms. At baseline, 46.9% had microscopic Plasmodium falciparum gametocytaemia. Both recurrences in the DHA/PPQ arm lost Pfmdr1 copy number amplification at recrudescence. All four recurrences in the ATQ/PG arm were wild-type for cytochrome bc1. One subject withdrew from the ATQ/PG arm due to drug allergy.

CONCLUSIONS

This study was conducted at the epicentre of substantial multi-drug resistance that emerged soon thereafter. Occurring early in the national transition from AS/MQ to DHA/PPQ, both DHA/PPQ and ATQ/PG had acceptable efficacy against uncomplicated falciparum malaria. However, efficacy of AS/MQ was only 80% with apparent mefloquine resistance based on elevated Pfmdr1 copy number and IC50. By 2009, there was already significant evidence of artemisinin resistance not previously reported at the Northern Cambodia-Thai border. This study suggests the basis for early development of significant DHA/PPQ failures within 3 years of introduction. Artemisinin resistance likely occurred on the Northern border concurrently with that reported along the Western border in Pailin. Trial registration This legacy trial was conducted prior to International Committee of Medical Journal Editors' requirements for preregistration on ClinicalTrials.gov. The full protocol has been provided.

Analysis of polycyclic aromatic hydrocarbons (PAHs) in surface sediments and edible aquatic species in an oil-contaminated mangrove ecosystem in Bodo, Niger Delta, Nigeria: Bioaccumulation and human health risk assessment

This work investigated the occurrence and risks associated with polycyclic aromatic hydrocarbons (PAHs) in tissues from five commonly consumed aquatic species (swimming crabs, estuarine shrimp, tiger prawns, periwinkles, and tilapia) and sediment across six sites in the area around Bodo town, in the Niger Delta region of Nigeria. We aimed to establish a relationship between PAH concentrations in sediment and biota, and to derive biota-sediment accumulation factors (BSAFs). Risks to human health associated with consumption of impacted food sources were assessed based on measured biotic concentrations of PAHs. The average concentration of PAHs and the number of PAHs measured above the limit of quantification varied greatly between different biota, with the lowest average concentrations observed in tilapia, followed by tiger prawns, crabs, estuarine shrimp, and the highest concentrations were observed in periwinkles. Similar to biotic concentrations, BSAFs were found to vary greatly across species, sites, and PAHs, though BSAFs for all organisms except periwinkles were below a value of 1. In periwinkles, BSAFs exceeded a value of 1 for phenanthrene (BSAF = 1.7), pyrene (1.5) and benzo[k]fluoranthene (1.7). Risks to human health associated with consumption of these species were assessed using the BaP toxic-equivalent approach for cancer risks and the toxic unit approach which jointly considered carcinogenic but also non-cancer hazards. The BaP toxic-equivalent approach showed that the excess lifetime cancer risk resulting from daily consumption of 0.2 kg of seafood ranged between 1.3 × 10^-6 for tiger prawn and tilapia to 4.1 × 10^-6 for periwinkles, which is below the excess lifetime cancer risk of 10^-4 used by Dutch and Nigerian authorities for sediment intervention values. This finding is supported by the results obtained from the toxic unit approach which indicates that the ratios of the estimated dose and the maximal permissible risk level for summed PAHs never exceeded 1.

699 EMBEDDING A FRAILTY TEAM AND UNIT INTO WYTHENSHAWE HOSPITAL’S EMERGENCY DEPARTMENT

Introduction

Evaluation of Wythenshawe Hospital’s Acute Frailty Service in January–June 2019 demonstrated slow referrals times and poor identification of frail patients due to inaccurate Clinical Frailty Scoring (CFS) at emergency department triage. This project presents the results of ongoing quality assessment of our service between June 2019–January 2021, following two quality improvement (QI) interventions.

Aims: To evaluate our service’s ability to deliver early identification and intervention for complex frail patients via Complex Geriatric Assessment (CGA), as set out in National and Regional Frailty standards.(1,2). -To improve and maintain better outcomes for patients accessing our frailty service.

Method

Intervention1 (July’19): Specialist frailty nurses relocated to ED. Dedicated frailty clinical fellows and Consultant geriatrician input 0900–1700 weekdays. Intervention2 (Sep’20): Short-stay frailty unit opened. Junior clinical fellow cover increased (0900–1900 weekdays and 0900–1700 weekends). 299 patients seen at intervals between Jun’19-Jan’21 analysed using electronic records and completed CGA proformas.

Results

Pre-intervention Intervention1 Intervention2 June’19(n = 22) July’19(n = 198) Nov’19(n = 25) Sep’20(n = 26) Jan’21(n = 28) Time from triage-to-CGA (mins) (CI 95%)* 372.0 ± 178.2 56.0 83.4 ± 31.0 72.9 ± 35.7 48.4 ± 20.0 Discharge(%): Same day 22.7 39.4 21.7 36.0 25.0 < 72 hr(cumulative) 72.7 63.6 47.8 68.0 57.1 Ave. length of stay(days)(CI95%) 10.4 ± 5.9 20.6 20.0 ± 8.7 7.1 ± 3.4 5.4 ± 2.1 Readmission <30 days(%) 30.0 9.0 17.4 12.5 25.0 CGA Quality(%) CFS completion 100 96.0100 89.3 ReSPECT discussion 29.3 64.0 61.5 67.9 Full medication review 46.5 96.0 80.8 89.3 Therapy assessment 85.5 92.0 92.3 89.3 *patients triaged between 0800–1700.

Conclusion

Since Intervention1, Wythenshawe frailty service has sustained a reduction in triage-to-CGA time, maintained high percentages of same-day and < 72 hr discharges, and sustained high rates of CFS completion and therapy assessments. Following intervention2, average length of stay reduced. Increased readmission rates in Jan’21 were impacted by COVID-19. Additional interventions targeted at reducing readmission rates and increasing ReSPECT discussions should be implemented. 1. Greater Manchester Frailty Collaborative and Network, 2019. 2. Same-day acute frailty service, NHS improvement, 2019.

A Comparative Study of Circadian Rhythmicity and Photoperiodism in Closely Related Species of Blow Flies: External Coincidence, Maternal Induction, and Diapause at Northern Latitudes

This review compares adult locomotor activity rhythms and photoperiodic induction of diapause in 3 common species of blow fly, Calliphora vicina, Lucilia sericata, and Protophormia terraenovae. Activity rhythms were broadly similar in all 3 species, although P. terraenovae is much less sensitive to constant light inducing arrhythmicity. Photoperiodic induction of diapause, on the other hand, varies more widely between species. C. vicina and L. sericata overwinter in a larval diapause induced by autumnal short days (long nights) acting both maternally and directly upon the larvae. P. terraenovae, on the other hand, shows an adult (reproductive) diapause induced by short daylength and low temperature experienced by the larvae. In the Nanda-Hamner protocol, C. vicina shows 3 clear peaks of high diapause incidence in cycle lengths close to 24, 48, and 72 h, without dampening and therefore suggesting a photoperiodic mechanism based on a self-sustained circadian oscillator acting in a clock of the external coincidence type. Entrainment of the locomotor activity rhythm to extended Nanda-Hamner photocycles, as well as to LD cycles close to the limits of the primary range of entrainment, demonstrates that overt circadian rhythmicity may act as 'hands' of the otherwise covert photoperiodic system, as suggested by Bünning, nearly 8 decades ago. In 24 h LD cycles, both locomotor activity rhythms and the photoperiodic oscillator are set to constant phase (CT 12) at light-off, so that the photoperiodic clock measures changes in nightlength by the coincidence (or not) of dawn light with a 'photoinducible phase' late in the subjective night (at about CT 21.5 h) as photoperiod changes with the seasons. Apparent differences between quantitative and qualitative photoperiodic responses are discussed.

Acritical review and weight of evidence approach for assessing the bioaccumulation of phenanthrene in aquatic environments

Bioaccumulation (B) assessment is challenging because there are various B-metrics from laboratory and field studies, multiple criteria and thresholds for classifying bioaccumulative (B), very bioaccumulative (vB), and not bioaccumulative (nB) chemicals, as well as inherent variability and uncertainty in the data. These challenges can be met using a weight of evidence (WoE) approach. The Bioaccumulation Assessment Tool (BAT) provides a transparent WoE assessment framework that follows Organisation for Economic Co-operation and Development (OECD) principles for performing a WoE analysis. The BAT guides an evaluator through the process of data collection, generation, evaluation, and integration of various lines of evidence (LoE) (i.e., B-metrics) to inform decision-making. Phenanthrene (PHE) is a naturally occurring chemical for which extensive B and toxicokinetics data are available. A B assessment for PHE using the BAT is described that includes a critical evaluation of 74 measured in vivo LoE for fish and invertebrate species from laboratory and field studies. The number of LoE are reasonably well balanced across taxa (i.e., fish and invertebrates) and the different B-metrics. Additionally, in silico and in vitro biotransformation rate estimates and corresponding model-predicted B-metrics are included as corroborating evidence. Application of the BAT provides a consistent, coherent, and scientifically defensible WoE evaluation to conclude that PHE is not bioaccumulative (nB) because the overwhelming majority of the bioconcentration, bioaccumulation, and biomagnification metrics for both fish and invertebrates are below regulatory thresholds. An analysis of the relevant data using fugacity ratios is also provided, showing that PHE does not biomagnify in aquatic food webs. The critical review identifies recommendations to increase the consistency of B assessments, such as improved standardization of B testing guidelines, data reporting requirements for invertebrate studies, and consideration of temperature and salinity effects on certain B-metrics. Integr Environ Assess Manag 2021;17:911-925. © 2021 Concawe. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

An open dataset of Plasmodium falciparum genome variation in 7,000 worldwide samples

MalariaGEN is a data-sharing network that enables groups around the world to work together on the genomic epidemiology of malaria. Here we describe a new release of curated genome variation data on 7,000 Plasmodium falciparum samples from MalariaGEN partner studies in 28 malaria-endemic countries. High-quality genotype calls on 3 million single nucleotide polymorphisms (SNPs) and short indels were produced using a standardised analysis pipeline. Copy number variants associated with drug resistance and structural variants that cause failure of rapid diagnostic tests were also analysed.  Almost all samples showed genetic evidence of resistance to at least one antimalarial drug, and some samples from Southeast Asia carried markers of resistance to six commonly-used drugs. Genes expressed during the mosquito stage of the parasite life-cycle are prominent among loci that show strong geographic differentiation. By continuing to enlarge this open data resource we aim to facilitate research into the evolutionary processes affecting malaria control and to accelerate development of the surveillance toolkit required for malaria elimination.

An open dataset of Plasmodium falciparum genome variation in 7,000 worldwide samples

MalariaGEN is a data-sharing network that enables groups around the world to work together on the genomic epidemiology of malaria. Here we describe a new release of curated genome variation data on 7,000 Plasmodium falciparum samples from MalariaGEN partner studies in 28 malaria-endemic countries. High-quality genotype calls on 3 million single nucleotide polymorphisms (SNPs) and short indels were produced using a standardised analysis pipeline. Copy number variants associated with drug resistance and structural variants that cause failure of rapid diagnostic tests were also analysed.  Almost all samples showed genetic evidence of resistance to at least one antimalarial drug, and some samples from Southeast Asia carried markers of resistance to six commonly-used drugs. Genes expressed during the mosquito stage of the parasite life-cycle are prominent among loci that show strong geographic differentiation. By continuing to enlarge this open data resource we aim to facilitate research into the evolutionary processes affecting malaria control and to accelerate development of the surveillance toolkit required for malaria elimination.

Differential Association of Spirituality and Religiosity With Rumination: Implications for the Treatment of Depression

ABSTRACT

Recent studies have shown that religiosity (R) is associated with lower rates of depression, whereas spirituality (S) is associated with higher rates. Rumination has also been associated with higher rates of depression. Some have hypothesized that rumination mediates the differential association of religiosity and spirituality with depression. We empirically test this hypothesis in a longitudinal, multigenerational sample through associations between rumination and depression, R/S and depression, and R/S and rumination. Cross-sectionally, total rumination scores were predicted by spirituality (standardized β = 0.13; 95% confidence interval [CI], 0.00-0.26), with subscale (reflection, depression, and brooding) standardized betas ranging from 0.11 to 0.15 (95% CI, -0.03 to -0.29). Cross-sectionally, rumination was not predicted by religiosity. Longitudinally, and consistent with previous findings, religiosity, but not spirituality, predicted reduced depressive symptoms (standardized β = -0.3; 95% CI, -0.58 to -0.01). The association between spirituality and rumination was driven by millennials. Psychotherapies that target rumination for depression might therefore be especially effective in the millennial demographic.

Comparison of multimodal analgesia with thoracic epidural after transthoracic oesophagectomy

BACKGROUND

Thoracic epidural analgesia (TEA) has been regarded as the standard of care after oesophagectomy for pain control, but has several side-effects. Multimodal (intrathecal diamorphine, paravertebral and rectus sheath catheters) analgesia (MA) may facilitate postoperative mobilization by reducing hypotensive episodes and the need for vasopressors, but uncertainty exists about whether it provides comparable analgesia. This study aimed to determine whether MA provides comparable analgesia to TEA following transthoracic oesophagectomy.

METHODS

Consecutive patients undergoing oesophagectomy for cancer between January 2015 and December 2018 were grouped according to postoperative analgesia regimen. Propensity score matching (PSM) was used to account for treatment selection bias. Pain scores at rest and on movement, graded from 0 to 10, were used. The incidence of hypotensive episodes and the requirement for vasopressors were evaluated.

RESULTS

The study included 293 patients; 142 (48.5 per cent) received TEA and 151 (51.5 per cent) MA. After PSM, 100 patients remained in each group. Mean pain scores were significantly higher at rest in the MA group (day 1: 1.5 versus 0.8 in the TEA group, P = 0.017; day 2: 1.7 versus 0.9 respectively, P = 0.014; day 3: 1.2 versus 0.6, P = 0.047). Fewer patients receiving MA had a hypotensive episode (25 per cent versus 45 per cent in the TEA group; P = 0.003) and fewer required vasopressors (36 versus 53 per cent respectively; P = 0.016). There was no significant difference in the overall complication rate (71.0 versus 61.0 per cent; P = 0.136).

CONCLUSION

MA is less effective than TEA at controlling pain, but this difference may not be clinically significant. However, fewer patients experienced hypotension or required vasopressor support with MA; this may be beneficial within an enhanced recovery programme.

SARS-CoV-2 Testing of 11,884 Healthcare Workers at an Acute NHS Hospital Trust in England: A Retrospective Analysis

Healthcare workers (HCWs) are known to be at increased risk of infection with SARS-CoV-2, although whether these risks are equal across all roles is uncertain. Here we report a retrospective analysis of a large real-world dataset obtained from 10 March to 6 July 2020 in an NHS Foundation Trust in England with 17,126 employees. 3,338 HCWs underwent symptomatic PCR testing (14.4% positive, 2.8% of all staff) and 11,103 HCWs underwent serological testing for SARS-CoV-2 IgG (8.4% positive, 5.5% of all staff). Seropositivity was lower than other hospital settings in England but higher than community estimates. Increased test positivity rates were observed in HCWs from BAME backgrounds and residents in areas of higher social deprivation. A multiple logistic regression model adjusting for ethnicity and social deprivation confirmed statistically significant increases in the odds of testing positive in certain occupational groups, most notably domestic services staff, nurses, and health-care assistants. PCR testing of symptomatic HCWs appeared to underestimate overall infection levels, probably due to asymptomatic seroconversion. Clinical outcomes were reassuring, with only a small minority of HCWs with COVID-19 requiring hospitalization (2.3%) or ICU management (0.7%) and with no deaths. Despite a relatively low level of HCW infection compared to other UK cohorts, there were nevertheless important differences in test positivity rates between occupational groups, robust to adjustment for demographic factors such as ethnic background and social deprivation. Quantitative and qualitative studies are needed to better understand the factors contributing to this risk. Robust informatics solutions for HCW exposure data are essential to inform occupational monitoring.

Regenerative rehabilitation of catastrophic extremity injury in military conflicts and a review of recent developmental efforts

AIM OF THE REVIEW

This review aims to describe the current state of regenerative rehabilitation of severe military extremity injuries, and promising new therapies on the horizon.

DISCUSSION

The nature of warfare is rapidly shifting with information operations, autonomous weapons, and the threat of full-scale peer adversary conflicts threatening to create contested environments with delayed medical evacuation to definitive care. More destructive weapons will lead to more devastating injuries, creating new challenges for limb repair and restoration. Current paradigms of delayed rehabilitation following initial stabilization, damage control surgery, and prolonged antibiotic therapy will need to shift. Advances in regenerative medicine technologies offer the possibility of treatment along the continuum of care. Regenerative rehabilitation will begin at the point of injury and require a holistic, organ-systems approach.

CONCLUSIONS

Both technological improvements and a rapidly advancing understanding of injury pathophysiology will contribute to improved limb-salvage outcomes, and shift the calculus away from early limb amputation.

Implementation and evaluation of a novel, unofficial, trainee-organized hospital addiction medicine consultation service

BACKGROUND

To evaluate a novel, unofficial, trainee-organized, hospital addiction medicine consultation service (AMCS), we aimed to assess whether it was (1) acceptable to hospital providers and patients, (2) feasible to organize and deliver, and (3) impacted patient care. Methods: We performed a retrospective descriptive study of all AMCS consultations over the first 16 months. We determined acceptability via the number of referrals received from admitting services, and the proportion of referred patients who consented to consultation. We evaluated feasibility via continuation/growth of the service over time, and the proportion of referrals successfully completed before hospital discharge. As most referrals related to opioid use disorder, we determined impact through the proportion of eligible patients offered and initiated on opioid agonist therapy (OAT) in hospital, and the proportion of patients who filled their outpatient prescription or attended their first visit with their outpatient OAT prescriber. Results: The unofficial AMCS grew to involve six hospital-based residents and five supervising community-based addiction physicians. The service received 59 referrals, primarily related to injection opioid use, for 50 unique patients from 12 different admitting services. 90% of patients were seen before discharge, and 98% agreed to addiction medicine consultation. Among 34 patients with active moderate-severe opioid use disorder who were not already on OAT, 82% initiated OAT in hospital and 89% of these patients continued after discharge. Conclusions: Established in response to identified gaps in patient care and learning opportunities, a novel, unofficial, trainee-organized AMCS was acceptable, feasible, and positively impacted patient care over the first 16 months. This trainee-organized, unofficial AMCS could be used as a model for other hospitals that do not yet have an official AMCS.

Pulse shape discrimination and exploration of scintillation signals using convolutional neural networks

We demonstrate the use of a convolutional neural network to perform neutron-gamma pulse shape discrimination, where the only inputs to the network are the raw digitised silicon photomultiplier signals from a dual scintillator detector element made of 6Li F:ZnS(Ag) scintillator and PVT plastic. A realistic labelled dataset was created to train the network by exposing the detector to an AmBe source, and a data-driven method utilising a separate photomultiplier tube was used to assign labels to the recorded signals. This approach is compared to the charge integration and continuous wavelet transform methods and a simpler artificial neural net. It is found to provide superior levels of discrimination, achieving an area under the curve of 0.996 ± 0.003. We find that the neural network is capable of extracting interpretable features directly from the raw data. In addition, by visualising the high-dimensional representations of the network with the t-SNE algorithm, we discover that not only is this method robust to minor mislabeling of the training dataset but that it is possible to identify an underlying substructure within the signals that goes beyond the original labelling. This technique could be utilised to explore and cluster complex, raw detector data in a novel way that may reveal more insights than standard analysis methods.

The Western Equine Encephalitis Lyophilized, Inactivated Vaccine: An Update on Safety and Immunogenicity

Background

Western Equine Encephalitis (WEE) is a naturally acquired infection and potentially devastating bioweapon, with no specific human countermeasures. An experimental inactivated Western Equine Encephalitis Vaccine (WEEV; WEE TSI-GSD 210) has been used under an IND (investigational New Drug) protocol at the United States Army Medical Research Institute of Infectious Diseases (USAMRIID) since 1976.

Methods

Over 24 years from 1987 to 2011, 876 subjects received 3 primary vaccine doses under 3 studies with 1,537 booster doses administered (FY87-8, phase 2, laboratory workers, vaccine lots 1-81-1, 1-81-2, and 2-1-91; FY99-12, phase 2 laboratory workers, lot 2-1-91; and FY09-02, phase 1 healthy volunteer, lot 3-1-92). Post-vaccination safety and immunogenicity [plaque reduction neutralization test 80% (PRNT₈₀) > 1:40] were analyzed.

Results

Overall PRNT₈₀ response to the primary series in FY87-8 was 42% (326/770) but dropped to 16% (14/87) in FY99-12, prompting study FY09-02, which achieved 89% (17/19). The first booster response rate was 68% (814/1194) in FY87-8, 53% (171/324) in FY99-12, and 100% (10/10) in FY09-02. The majority of definitely related adverse reactions (AEs) were mild and local with no definitely related serious AEs. No laboratory acquired WEE infection was documented during this period despite 4 reported exposures in vaccinated subjects.

Conclusion

The TSI-GSD 210 WEE vaccine was immunogenic, safe and well tolerated. Use of this vaccine could be considered in an emergency setting. Despite decades of safe and effective use under IND, full licensure is not planned due to manufacturing constraints, and a strategic decision to develop alternatives.

Clinical Trial Registration

https://clinicaltrials.gov/, identifier NCT01159561.

Cigarette-smoking characteristics and interest in cessation in patients with head-and-neck cancer

Purpose

Many patients diagnosed with head-and-neck cancer are current or former smokers. Despite the well-known adverse effects of smoking, continuation of smoking during cancer treatment is associated with reduced efficacy of that treatment and with cancer recurrence. In the present study, we examined smoking characteristics in patients with head-and-neck cancer near the time of cancer treatment.

Methods

A prospective cohort of patients with head-and-neck cancer who attended a dental oncology clinic before receiving cancer treatment at a regional cancer centre were invited to participate in a study that involved completing an interviewer-administered questionnaire to assess smoking characteristics, intention to quit, motivation to quit, and strategies perceived to potentially aid in successful cessation.

Results

The study enrolled 493 ever-smokers, with a response rate of 96.1% and a self-reported current smoker rate of 37.1% (n = 183). Most of the current smokers reported high nicotine dependence, with 84.7% (n = 155) indicating a time to first cigarette of 30 minutes or less. Most had previously attempted to quit smoking (77.0%), and many had prior unsuccessful quit attempts before resuming smoking again. Most were interested in quitting smoking (85.8%), and many (70.5%) were seriously considering quitting smoking within the subsequent 30 days.

Conclusions

Patients with head-and-neck cancer reported high nicotine dependence and high interest in cessation opportunities near the time of treatment for cancer. Those results might provide support for provision of smoking cessation opportunities.

Is the Arrhenius-correction of biodegradation rates, as recommended through REACH guidance, fit for environmentally relevant conditions? An example from petroleum biodegradation in environmental systems

Biodegradation is a major determinant of chemical persistence in the environment and an important consideration for PBT and environmental risk assessments. It is influenced by several environmental factors including temperature and microbial community structure. According to REACH guidance, a temperature correction based on the Arrhenius equation is recommended for chemical persistence data not performed at the recommended EU mean surface water temperature. Such corrections, however, can lead to overly conservative P/vP assessments. In this paper, the relevance of this temperature correction is assessed for petroleum hydrocarbons, using measured surface water (marine and freshwater) degradation half-time (DT50) and degradation half-life (HL) data compiled from relevant literature. Stringent screening criteria were used to specifically select data from biodegradation tests containing indigenous microbes and conducted at temperatures close to their ambient sampling temperature. As a result, ten independent studies were identified, with 993 data points covering 326 hydrocarbon constituents. These data were derived from tests conducted with natural seawater, or freshwater, at temperatures ranging from 5 to 21 °C. Regressions were performed on the full hydrocarbon dataset and on several individual hydrocarbons. The results were compared to the trend as predicted by the Arrhenius equation and using the activation energy (E_a) as recommend in the REACH Guidance. The comparison shows that the correction recommended in REACH Guidance over predicts the effect of temperature on hydrocarbon biodegradation. These results contrast with temperature manipulated inocula where the test temperature is different from the ambient sampling temperature. In these manipulated systems, the effect of temperature follows the Arrhenius equation more closely. In addition, a more striking effect of temperature on the lag phase was observed with longer lag phases more apparent at lower temperatures. This indicates that the effect of temperature may indeed be even lower when considering hydrocarbon biodegradation without the initial lag phase.