Marijuana smoking as a possible cause of tongue carcinoma in young patients

Acoustic Characteristics of Mandarin Speech in Male Drug Users

AIM

Drug use/addiction has a profound impact on the physical and mental health of individuals. Previous studies have indicated that drug users may experience speech perception disorders, including speech illusion and challenges in recognizing emotional speech. However, the influence of drugs on speech production, as another crucial aspect of speech communication, has not been thoroughly examined. Therefore, the current study aimed to investigate how drugs affect the acoustic characteristics of speech in Chinese male drug users.

METHOD

Speech recordings were collected from a total of 160 male drug users (including 106 heroin users, 23 ketamine users, and 31 methamphetamine users) and 55 male healthy controls with no history of drug use. Acoustic analysis was conducted on the collected speech data from these groups, and classification analysis was performed using five supervised learning algorithms.

RESULTS

The results demonstrated that drug users exhibited smaller F0 standard deviation, reduced loudness, cepstral peak prominence, and formant relative energies, as well as higher H1-A3, longer unvoiced segments, and fewer voiced segments per second compared to the control group. The classification analyses yielded good performance in classifying drug users and non-drug users, with an accuracy above 86%. Moreover, the identification of the three groups of drug users achieved an accuracy of approximately 70%. Additionally, the study revealed different effects on speech production among the three types of drugs.

CONCLUSION

The above findings indicate the presence of speech disorders, such as vocal hoarseness, in drug users, thus confirming the assumption that the acoustic characteristics of speech in drug users deviates from the norm. This study not only fills the knowledge gap regarding the effects of drugs on the speech production of Chinese male drug users but also provides a more comprehensive understanding of how drugs impact human behaviors. Furthermore, this research provides theoretical foundations of detoxification and speech rehabilitation for drug users.

A critical review of cannabis in medicine and dentistry: A look back and the path forward

Introduction

In the last two decades, our understanding of the therapeutic utility and medicinal properties of cannabis has greatly changed. This change has been accompanied by widespread cannabis use in various communities and different age groups, especially within the United States. With this increase, we should consider the potential effects of cannabis–hemp on general public health and how they could alter therapeutic outcomes.

Material and Methods

The present investigation examined cannabis use for recreational and therapeutic use and a review of pertinent indexed literature was performed. The focused question evaluates “how cannabis or hemp products impact health parameters and do they provide potential therapeutic value in dentistry, and how do they interact with conventional medicines (drugs).” Indexed databases (PubMed/Medline, EMBASE) were searched without any time restrictions but language was restricted to English.

Results

The review highlights dental concerns of cannabis usage, the need to understand the endocannabinoid system (ECS), cannabinoid receptor system, its endogenous ligands, pharmacology, metabolism, current oral health, and medical dilemma to ascertain the detrimental or beneficial effects of using cannabis–hemp products. The pharmacological effects of pure cannabidiol (CBD) have been studied extensively while cannabis extracts can vary significantly and lack empirical studies. Several metabolic pathways are affected by cannabis use and could pose a potential drug interaction. The chronic use of cannabis is associated with health issues, but the therapeutic potential is multifold since there is a regulatory role of ECS in many pathologies.

Conclusion

Current shortcomings in understanding the benefits of cannabis or hemp products are limited due to pharmacological and clinical effects not being predictable, while marketed products vary greatly in phytocompounds warrant further empirical investigation. Given the healthcare challenges to manage acute and chronic pain, this review highlights both cannabis and CBD‐hemp extracts to help identify the therapeutic application for patient populations suffering from anxiety, inflammation, and dental pain.

Cannabis and the skin

The public and health care providers are increasingly curious about the potential medical benefits of Cannabis. In vitro and in vivo studies of Cannabis have suggested it has favorable effects on regulating pain, pruritus, and inflammation, making it a potentially attractive therapeutic agent for many dermatologic conditions. The body of literature reporting on the role of cannabinoids in dermatology is in its infancy but growing. We review the current research, possible cutaneous adverse effects, and future directions for cannabinoids and their use in skin cancer, acne, psoriasis, pruritus, dermatitis, scleroderma, dermatomyositis, cutaneous lupus erythematous, epidermolysis bullosa, pain, and wound healing.

The Risks and Benefits of Cannabis in the Dermatology Clinic

Cannabis ( Cannabis sativa/indica), also known as marijuana, has been used for medicinal and recreational purposes for millennia. There has been a recent trend to legalize the use of cannabis, as illustrated by the recent legalization votes in numerous states in the United States and legislation in Canada to allow recreational cannabis use. With this increasing consumption of cannabis, dermatologists will see increased pressure to prescribe cannabis and will see the side effects of cannabis use with greater frequency. There are several approved medical indications for cannabis use, including psoriasis, lupus, nail-patella syndrome, and severe pain. In addition, very preliminary studies have suggested cannabis and its derivatives might have use in acne, dermatitis, pruritus, wound healing, and skin cancer. Further well-controlled studies are required to explore these potential uses. Conversely, the side effects of cannabis use are relatively well documented, and dermatologists should be aware of these presentations. Side effects of cannabis use include cannabis allergy manifesting as urticaria and pruritus, cannabis arteritis presenting with necrosis and ulcers, and oral cancers from cannabis smoke. In this review, we summarize some of the studies and reports regarding the medicinal uses of cannabis in the dermatology clinic and some of the side effects that might present more often to dermatologists as the use of cannabis increases.

Vocal assessment of addicts on methadone therapy via the RBH scale and objective acoustic parameters

INTRODUCTION

A large number of people around the world struggle daily to become free of their addiction to illegal psychoactive substances. In order to create an atmosphere of improved supervision, established communication and improved quality of life for drug addicts, centers have been set up to provide methadone as a substitute.

OBJECTIVE

The aim of the research was to assess the vocal features of drug addicts on methadone therapy via subjective and objective parameters, to ascertain if vocal damage has occurred and to determine whether subjective and objective acoustic vocal parameters are related, and how.

METHODS

The research included 34 adults of both genders who were undergoing methadone treatment. A subjective vocal evaluation assessed voice pitch and clarity, while the subjective acoustic analysis utilized the Roughness-Breathiness-Hoarseness scale of roughness-breathiness-hoarseness. Objective acoustic analysis was conducted after recording and analyzing an uninterrupted vocal /a/ of at least three seconds duration, using the "GllotisController" software.

RESULTS

The subjective acoustic analysis using the Roughness-Breathiness-Hoarseness scale showed pathological values in 52.9% male and 47% female participants. The average values of the roughness-breathiness-hoarseness for the entire sample were 0.91, 0.38 and 0.50, respectively. Lower roughness was associated with a higher fundamental frequency (f₀) and lower jitter and shimmer values (p<0.05). There was a statistically significant correlation between breathiness, jitter (p<0.01) and shimmer (p<0.05), and between hoarseness and jitter (p<0.01).

CONCLUSION

A statistically significant correlation was found between the two subjective vocal assessments, voice clarity and pitch, and Roughness-Breathiness-Hoarseness scale, and the parameters of the objective acoustic vocal assessment.

Management of cannabis-induced periodontitis via resective surgical therapy: A clinical report

BACKGROUND AND OVERVIEW

There is a lack of clinical research on the potential effect of cannabis use on the periodontium as well as its effect on treatment outcomes. The aim of this case report is to illustrate the clinical presentation of periodontal disease in a young woman who was a chronic cannabis user, as well as successful treatment involving motivating the patient to quit cannabis use and undergo nonsurgical and surgical therapy.

CASE DESCRIPTION

A 23-year-old woman sought care at the dental clinic for periodontal treatment. During a review of her medical history, the patient reported using cannabis frequently during a 3-year period, which coincided with the occurrence of gingival inflammation. She used cannabis in the form of cigarettes that were placed at the mandibular anterior region of her mouth for prolonged periods. Localized prominent papillary and marginal gingival enlargement of the anterior mandible were present. The mandibular anterior teeth showed localized severe chronic periodontitis. The clinicians informed the patient about the potentially detrimental consequences of continued cannabis use; she was encouraged to quit, which she did. The clinicians performed nonsurgical therapy (scaling and root planing) and osseous surgery. The treatment outcome was evaluated over 6 months; improved radiographic and clinical results were observed throughout the follow-up period.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

Substantial availability and usage of cannabis, specifically among young adults, requires dentists to be vigilant about clinical indications of cannabis use and to provide appropriate treatments. Behavioral modification, nonsurgical therapy, and surgical therapy offer the potential for successful management of cannabis-related periodontitis.

Dental treatment planning considerations for patients using cannabis: A case report

BACKGROUND AND OVERVIEW

There is a deficit in clinical research on the potential risks involved in treating dental patients who use cannabis for either medicinal or recreational purposes. The aim of this case report is to illustrate the need for additional education for oral health care professionals so they can understand the wide variety of available cannabis options and their potential effects on dental treatment.

CASE DESCRIPTION

A 27-year-old man sought care at the dental clinic with a nonrestorable molar requiring extraction. During the review of his medical history, the patient reported taking a "dab" of marijuana approximately 5 hours before his appointment. Because of the admission of recent illicit drug use, no treatment was rendered. The patient was offered an appointment the next day but he refused, citing bias in regard to his cannabis use.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

The number of Americans using marijuana is increasing rapidly. Twenty-three states and the District of Columbia have laws legalizing cannabis to some degree, and Alaska, Colorado, Oregon, and Washington have legalized marijuana for recreational use. This drastic upswing in availability and usage will require dentists to address the possible effects of cannabis on dental practices. It is imperative that dental care providers make clinical decisions based on scientific evidence regarding the pharmacologic and psychological effects of marijuana, not on the societal stigma associated with illegal drug use. Dentists should be familiar with popular delivery systems and understand the differences between various marijuana options. Clinical guidelines may need to be developed to help providers assess the patient's degree of cognitive impairment. Dentists should be able to advise patients on the potential consequences of this habit on their oral health.

Uso de substâncias psicoativas, alterações vocais e qualidade de vida em usuários de drogas lícitas e ilícitas

OBJETIVOS:investigar a qualidade de vida e voz, além das principais alterações perceptivo-auditivas e as medidas acústicas jitter, shimmer e Glottal Noise Excitation em usuários de substâncias psicoativas lícitas e/ou ilícitas que buscaram um centro de tratamento para dependência química.MÉTODOS:estudo transversal. Os participantes responderam aos questionários de Mensuração de Qualidade de Vida em Voze World Health Organization Quality of Life Instrument-Bref. Além disso foi realizado, um registro vocal da vogal /a/ e de uma contagem de números de 1 a 20. Os registros vocais foram avaliados por meio da escala GRBAS-I (G - grau global da disfonia, R - rugosidade, B - soprosidade, A - astenia, S - tensão) e a análise acústica (jitter, shimmer, Glottal noise excitation) pelo software VoxMetria.RESULTADOS:avaliaram-se 29 protocolos e registros de voz; na amostra, 19 (65,5%) eram homens; a idade média da amostra foi de 37,8 anos. Os escores de ambos os questionários não apresentaram diferenças entre os usuários de drogas lícitas e os de drogas ilícitas. Na análise perceptiva por meio da GRBAS-I, eles mostraram predominância de alterações discretas e moderadas nos itens grau geral da disfonia, rugosidade e instabilidade para usuárias de drogas ilícitas. A medida acústica jitter e o shimmerestavam alterados para homens e mulheres, e o desvio padrão da frequência fundamental também estava alterado.CONCLUSÃO:alterações de qualidade de vida e voz foram identificadas em ambos os usuários. A maioria dos usuários apresentou alterações nas medidas de jittere shimmer.Usuários de drogas ilícitas apresentaram mais alterações de Glottal Noise Excitation e desvio padrão da frequência fundamental.

Bogarting that joint might decrease oral HPV among cannabis users

Human papilloma virus (HPV) has many known strains, two of the most well studied perhaps being the high-risk types 16 and 18. These strains have attracted more interest because they are known to disrupt tumour-suppressor genes that control the cell cycle, rendering those genes less effective at keeping cell division in check.Within the last decade, an increase in oral hpv-linked cancers of the throat and tongue has been attributed to exposure and contraction of hpv through oral sex, most notably in younger people. An understudied and arguably equal contributor to oral hpv infection might be indirect contact with an infected person. Presented here is a brief but important perspective on the relationship between cannabis use and oral cancer. The development of oral cancer is not a result of smoking cannabis per se; rather, it is hypothesized to be a result of contracting hpv through various forms of sharing and passing joints and other smoking apparatuses. Therefore, it is hypothesized that bogarting (and not passing) joints might decrease oral hpv among cannabis smokers. Future research should therefore investigate the prevalence of oral hpv in cannabis smokers to better understand its epidemiology.

Effect of cannabis usage on the oral environment: a review

AIM

To evaluate oral environmental changes in cannabis users.

MATERIAL AND METHODS

The MEDLINE and Cochrane Central register of controlled trails (CENTRAL) were searched up to April 2007 to identify appropriate studies.

RESULTS

Independent screening of 982 titles and abstracts (MEDLINE-Pubmed) and (Cochrane) papers resulted in seven eligible publications.

CONCLUSION

Based on the limited data, it seems justified to conclude that with increasing prevalence of cannabis use, oral health care providers should be aware of cannabis-associated oral side effects, such as xerostemia, leukoedema and an increased prevalence and density of Candida albicans.

Salivary glutathione and uric acid levels in patients with head and neck squamous cell carcinoma

BACKGROUND

We evaluated the concentrations of glutathione and uric acid, low molecular weight antioxidants, in saliva of patients with head and neck squamous cell carcinoma (HNSCC), in order to identify differences with normal subjects and to obtain information about biochemical alterations of human saliva during carcinogenesis.

METHODS

We compared 50 HNSCC patients, divided in 2 subsets on the basis of tumor site, with a control group of 77 subjects, without a previous diagnosis of HNSCC, matched for age, sex, alcohol consumption, and smoking status.

RESULTS

At tests for equality of means by Welch and Brown-Forsythe, differences between groups resulted probable for salivary levels of glutathione (p = .004 and p < .001 respectively) but not for salivary levels of uric acid (p = .228 and p = .122 respectively). Comparing groups by Tamhane test, the patients with oral or pharyngeal cancer had significantly higher salivary levels of glutathione than both controls and patients with laryngeal cancer.

CONCLUSIONS

Salivary glutathione levels may be an index of oxidative stress at the level of the upper airways and in particular of oral cavity and pharynx. Therefore, high salivary glutathione may be an epidemiological marker to identify subjects with an increased risk of developing HNSCC, to submit to strict follow-up and chemoprevention. Metabolic alterations of saliva could be both an epidemiological marker and a target for chemoprevention of oral and oropharyngeal carcinogenesis.

Pilot phase IIA study for evaluation of the efficacy of folic acid in the treatment of laryngeal leucoplakia

BACKGROUND

It has been previously observed that patients with head and neck squamous cell carcinoma or with laryngeal leucoplakia present a significant reduction in plasma folate levels. The current Phase IIA pilot study assessed the effectiveness of folic acid as a chemopreventive agent in patients affected by glottic laryngeal leucoplakia.

METHODS

Forty-three untreated patients affected by glottic laryngeal leucoplakia were enrolled in the Ear, Nose, and Throat Department (Universita Cattolica del Saco Cuore, Rome, Italy). Glottic leucoplakia was initially diagnosed by indirect laryngoscopy and successively confirmed by diagnostic direct microlaryngoscopy with a biopsy for histologic assessment. Folic acid (Folina, Schwarz Pharma, Germany) was administered orally (5 mg every 8 hours) for 6 months. Patients were monitored every 30 days by videolaryngoscopy.

RESULTS

Twelve (28%) patients had no response, 19 (44%) had a partial response, and 12 (28%) had a complete response. The mean increase in serum folate levels (10.06 +/- 0.53) and the mean decrease in homocysteine serum (3.65349 +/- 0.85526) at the end of the study were highly significant (P = .0001).

CONCLUSIONS

The larynx is 1 of the sites of major interest and a good model for the development of chemopreventive agents, but so far the proposed agents have shown no clear efficacy on precancerous lesions or on the development of second malignancies.

GSTT1 and GSTM1 allelic polymorphisms in head and neck cancer patients from Italian Lazio Region

BACKGROUND

The association between head and neck squamous cell carcinoma (HNSCC) and allelic variants of glutathione S-transferase M1 (GSTM1) and -T1 (GSTT1) is currently controversial. The present study investigates the prevalences of GSTT1 and GSTM1 polymorphism in a cohort of 100 head and neck cancer patients, 100 healthy donors and 200 controls with non-neoplastic head and neck diseases from Italian Lazio Region.

METHODS

The patients with benign head and neck pathologies, as well as the healthy donors were matched for age, sex, cigarette smoke (yes/no) and alcohol consumption (yes/no). Molecular definition of GSTT1 and GSTM1 genotype has been performed by means of allele-specific PCR technique.

RESULTS

A significant association between head and neck cancer and GSTM1 null genotype was observed both considering benign disease controls (p=0.001, OR=2.613; 95% C.I.=1.48-4.62), and healthy donors (p=0.0003, OR=3.35; 95% C.I. 1.69-6.67) while no significant association was found with GSTT1 null genotype (p>or=0.14). No interactive association was observed when combining the different genotypes of the two polymorphisms. These results were confirmed after correction for daily number of cigarettes and period of tobacco exposure.

CONCLUSIONS

The present study confirms a role for genetic alterations of GSTM1 detoxifying enzyme as a risk factor for the development of HNSCC in patients from the Italian Lazio Region, independently of age, sex and other confounding variables.

Transitional cell carcinoma associated with marijuana: Case report and review of the literature

Transitional cell carcinoma of the bladder tends to occur in older patients with a history of tobacco use. We recently evaluated and treated a 45-year-old man with a history of heavy marijuana use. The patient's only risk factor for transitional cell carcinoma was the inhalation of up to five marijuana cigarettes daily for more than 30 years. We present our case and review the literature.

General and oral health implications of cannabis use

Cannabis, commonly known as marijuana, is the most frequently used illicit drug in Australia. Therefore, oral health care providers are likely to encounter patients who are regular users. An upward trend in cannabis use is occurring in Australia, with 40 per cent of the population aged 14 and above having used the drug. There are three main forms of cannabis: marijuana, hash and hash oil, all of which contain the main psychoactive constituent delta-9-tetrahydrocannabinol (THC). Cannabis is most commonly smoked, however it can be added to foods. THC from cannabis enters the bloodstream and exerts its effects on the body via interaction with endogenous receptors. Cannabis affects almost every system of the body, particularly the cardiovascular, respiratory and immune systems. It also has acute and chronic effects on the mental health of some users. Therefore, chronic abuse is a concern because of its negative effects on general physical and mental health. Cannabis abusers generally have poorer oral health than non-users, with an increased risk of dental caries and periodontal diseases. Cannabis smoke acts as a carcinogen and is associated with dysplastic changes and pre-malignant lesions within the oral mucosa. Users are also prone to oral infections, possibly due to the immunosuppressive effects. Dental treatment on patients intoxicated on cannabis can result in the patient experiencing acute anxiety, dysphoria and psychotic-like paranoiac thoughts. The use of local anaesthetic containing epinephrine may seriously prolong tachycardia already induced by an acute dose of cannabis. Oral health care providers should be aware of the diverse adverse effects of cannabis on general and oral health and incorporate questions about patients' patterns of use in the medical history.

Squamous cell carcinoma of the oral cavity in patients aged 45 years and under: a descriptive analysis of 116 cases diagnosed in the South East of England from 1990 to 1997

BACKGROUND

there is, currently, much anecdotal and some epidemiological evidence for a rise in oral cancer rates amongst younger individuals, many of whom have had no exposure to traditional risk factors such as tobacco and heavy alcohol use, or at least not the exposure over decades usually associated with this disease. The probity of this assertion and the presence or absence of traditional risk factors needs further evidence.

OBJECTIVES

this paper describes the demography and the exposure to potential risk factors amongst a cohort aged 45 years and younger, diagnosed with squamous cell carcinoma of the oral cavity between 1990 and 1997 from the South East of England.

MATERIALS AND METHODS

eligible patients registered with a cancer registry were included in this retrospective study. Information was accessed from the database and by a postal questionnaire survey. The self-completed questionnaire contained items about exposure to the following risk factors: tobacco; alcohol; diet; frequency of dental visits and familial cancer.

RESULTS AND CONCLUSIONS

this is the largest UK epidemiological study so far to be undertaken on young subjects diagnosed with oral cancer. One-hundred and sixteen cases were recruited representing a response rate of 59%. Slightly over 90% of this cohort were classified as white European. A large proportion of cases (40%) were from social classes I & II suggesting either a true social class difference in young cases versus older oral cancer cases or a possible bias in responders or survivors. Risk factors of tobacco use and excessive alcohol consumption were present in the majority (75%) of patients. Significant differences in the pattern of alcohol consumption were found in female subjects, who were less likely to consume over the recommended amounts of alcohol compared with male subjects. Daily regular fresh fruit and vegetable consumption during the ten year period before cancer diagnosis was recorded to be low. There was a distinct subgroup of cases, 26% of the group, that showed little, if any, exposure to any major risk factors.

Marijuana smoking and head and neck cancer

A recent epidemiological study showed that marijuana smoking was associated with an increased risk of head and neck cancer. Among high school students and young adults, the prevalence of marijuana use was on the rise in the 1990s, with a simultaneous decline in the perception that marijuana use is harmful. It will be a major public health challenge to make people aware of the harmful effects of marijuana smoking, when some people view it as the illicit drug with the least risk. The carcinogenicity of delta9-tetrahydrocannabinol (THC) is not clear, but according to laboratory studies, it appears to have antitumor properties such as apoptosis as well as tumor-promoting properties such as limiting immune function and increasing reactive oxygen species. Marijuana tar contains similar carcinogens to tar from tobacco cigarettes, but each marijuana cigarette maybe more harmful than a tobacco cigarette since more tar is inhaled and retained when smoking marijuana. More molecular alterations have been observed in bronchial mucosa specimens of marijuana smokers compared to nonsmokers. Field cancerization may be occurring on the bronchial epithelium due to marijuana smoking exposure. Several case studies were suggestive of an association of marijuana smoking with head and neck cancers and oral lesions. However, in a cohort study with 8 years of follow-up, marijuana use was not associated with increased risks of all cancers or smoking-related cancers. Further epidemiological studies are necessary to confirm the association of marijuana smoking with head and neck cancers and to examine marijuana smoking as a risk factor for lung cancer. It will also be of interest to examine potential field cancerization of the upper aerodigestive tract by marijuana and to explore marijuana as a risk factor for oral premalignant lesions.

Induction and regulation of the carcinogen-metabolizing enzyme CYP1A1 by marijuana smoke and delta (9)-tetrahydrocannabinol

Induction of the carcinogen-metabolizing enzyme cytochrome P4501A1 (CYP1A1) is a key step in the development of tobacco-related cancers. To determine if marijuana smoke activates CYP1A1, a murine hepatoma cell line expressing an inducible CYP1A1 gene (Hepa-1) was exposed in vitro to tar extracts prepared from either tobacco, marijuana, or placebo marijuana cigarettes. Marijuana tar induced higher levels of CYP1A1 messenger RNA (mRNA) than did tobacco tar, yet resulted in much lower CYP1A1 enzyme activity. These differences between marijuana and tobacco were primarily due to Delta(9)-tetrahydrocannabinol (Delta(9)-THC), the psychoactive component of marijuana. Here we show that Delta(9)-THC acts through the aryl hydrocarbon receptor complex to activate transcription of CYP1A1. A 2-microg/ml concentration of Delta(9)-THC produced an average 2.5-fold induction of CYP1A1 mRNA, whereas a 10- microg/ml concentration of Delta(9)-THC produced a 4.3-fold induction. No induction was observed in Hepa-1 mutants lacking functional aryl-hydrocarbon receptor or aryl-hydrocarbon receptor nuclear translocator genes. At the same time, Delta(9)-THC competitively inhibited the CYP1A1 enzyme, reducing its ability to metabolize other substrates. Spiking tobacco tar with Delta(9)-THC resulted in a dose-dependent decrease in the ability to generate CYP1A1 enzyme activity as measured by the ethoxyresorufin-o-deethylase (EROD) assay. This inhibitory effect was confirmed by Michaelis-Menton kinetic analyses using recombinant human CYP1A1 enzyme expressed in insect microsomes. This complex regulation of CYP1A1 by marijuana smoke and the Delta(9)-THC that it contains has implications for the role of marijuana as a cancer risk factor.

Mutagenicity, developmental toxicity and carcinogenicity of cannabis

Data on the mutagenicity, developmental toxicity and carcinogenicity of cannabis are reviewed in this article. The available evidence on the possible mutagenic effects of cannabinoids is still inconclusive. There is no consensus on the induction of point mutations, while some experimental results suggest that cannabinoids may cause chromosomal damage. Concerning the developmental effects of cannabis, an increased embryolethality and somatic growth retardation have been observed in animals, as well as changes in motor behaviour, after perinatal exposure to cannabinoids. An elevated risk for infertility has been suggested for women smoking marijuana. On the other hand, intrauterine exposure to cannabinoids may be followed by changes of behaviour later in childhood. Finally, the experimental work concerning the possible carcinogenic action of cannabinoids has shown that cannabis acts as a tumour promotor in animals. Epidemiological studies have incriminated cannabis smoking for the development of head and neck carcinomas and for carcinomas of the respiratory tract in humans, but several confounding factors have rendered this evidence inconclusive. At least part of the great popularity of cannabis smoking is due to the widespread belief that it is harmless. However, the studies presented in this review show that, despite their low acute toxicity profile, cannabinoids represent several risks in terms of chronic toxicity.

Oral precancer: preventive and medical approaches to management

Leukoplakias are among the most common potentially malignant oral lesions. Some are idiopathic, others are related to habits such as tobacco and/or alcohol use. Medical management includes reducing or abandoning these habits, increasing the intake of fruit and vegetables in the diet, and possibly the use of active agents. Retinoids, carotenoids and topical cytotoxic agents show promise, and newer therapies are on the horizon.

No increase in carcinogen-DNA adducts in the lungs of monkeys exposed chronically to marijuana smoke

Rhesus monkeys exposed to marijuana smoke either 7 or 2 days/weeks (HI and LO groups, respectively), or ethanol-extracted marijuana smoke for 7 days/week (EM) or sham treatment (SH) for 1 year were sacrificed 7 months following the last exposure. Pulmonary levels of carcinogen-DNA adducts were determined. Although mean or median adduct levels were not statistically different, 15 of 22 adduct measures were highest in the EM group and lowest 12 of 22 times in the SH group. The levels of aromatic carcinogen-DNA adducts seem no higher in the lungs of animals exposed to marijuana smoke than in untreated animals. Ethanol-extracted marijuana may have effects greater than marijuana itself.