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Biomedical subjects

P G Lewis

Publications and source records attributed to P G Lewis.

15 recordsLinked to original sources

Implications of hormesis for industrial hygiene.

This paper considers hormesis as a valid and potentially valuable alternative hypothesis for low-dose response in the context of occupational health risk assessment. It outlines the current occupational risk assessment paradigm and its use of high-dose toxicological data in setting occupational exposure limits (OELs). This present effort is a call to science to investigate the potential promise of hormesis in providing prima facie experimental evidence for a low-dose threshold of toxic effect to chemical agents. The scientific effort and advancement advised in this piece could also lead to experimentally validated quantitative estimates of the toxic effect extant at occupational exposures in the region of the OEL.

Animals↗

Jayjock and Lewis reply.

The current state-of-the-science, in our opinion, is incapable of accurately predicting the human health risk at environmental exposures to chemicals. We believe that dose-response models represent an integral part of the scientific method but that all models require valid scientific data in the realm of actual exposure in order to be derived and function properly. Given this current state, the evidence to date and the promise of hormesis to provide a detectable signal at low-dose, we view it as a variable and valuable hypothesis worthy of significant scientific effort.

Animals↗

Occupational and environmental medicine: moving the factory fence or hedging our bets?

Occupational and environmental medicine evolved out of concern for the effect of work hazards on health. The experienced gained in considering such hazards has been extended to understanding general risks in the environment. As we look toward the future, classical occupational and environmental hazards such as over exposure to lead, asbestos and mercury are waning and being replaced by concerns around sustainable development, toxicology testing and exposure information for high production volume chemicals, development of better approaches for setting workplace and community exposure limits, environmental justice and many others. The opportunities for the future exist in overcoming these new challenges.

Endocrine System Diseases↗

Employee response to a company-sponsored program of colorectal and prostate cancer screening.

Studies done in the mid-1970s documented increased risk for respiratory cancer and leukemia among employees in a chemical company manufacturing plant where chloromethyl ethers were used in production from 1948 to 1971. In the late 1980s, the company informed current and former employees about the results of follow-up studies which showed a moderation of risk of respiratory cancer and leukemia. New data showing elevated rates of mortality from colorectal, prostate, bladder, and pancreatic cancer in the population were also reported. Via mailed correspondence, the company made a no-cost program of colorectal and prostate cancer screening available to employees upon request; and information about bladder and pancreatic cancer was made available. Thirteen percent of employees in the population indicated interest in colorectal and prostate cancer screening (response). Thirty-one percent of these responders were screened (adherence). Multivariate analyses showed that education and length of employment in the plant were positively associated with response. Being white was positively associated with response for younger workers; while among older workers being male was positively associated with response. In terms of adherence, we found that older, more highly educated workers were more likely to have a screening examination. Findings indicate that employee participation in workplace-sponsored colorectal and prostate cancer screening can vary according to worker sociodemographic factors and length of employment in areas of potential exposure.

Age Factors↗

Formulation effect on the dermal bioavailability of isothiazolone biocide.

A central tenet of the science of toxicology is that the toxic effect of any material monotonically increases with the amount of the material delivered to the target tissue. This is the so-called dose-response relationship. Previous work is discussed in which a dose-response relationship is established for the induction and elicitation of cutaneous contact allergy from the isothiazolone biocide which is a 3 to 1 mixture of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one. The commercial product name for this mixture is Kathon LX biocide. Given a tissue dose-response, this current work determines and demonstrates a difference in risk from aqueous formulations with and without polymer. A lower delivered dose of biocide goes into the skin from an aqueous-based polymeric emulsion or paint than from an aqueous solution or oil-in-water emulsions without polymer. Thus, the estimate of risk, as a direct result of dose, and the determination of a safe use level of a biocide in any particular formulation matrix need to incorporate this reality.

Animals↗

Diabetes care in South Asian and white European patients with type 2 diabetes.

Aspects of diabetes care in South Asian and white European patients with Type 2 diabetes attending a hospital review clinic were explored. Among the clinic population of 1710 patients, 258 (15%) were of South Asian origin. A significantly greater proportion (95% CI for difference in proportions 8-22%) of these patients was treated with oral hypoglycaemic drugs than in white Europeans, in whom there was a correspondingly greater proportion receiving insulin treatment. In a case-control study, where 154 patients in each racial group were stratified according to treatment regimen, significantly more South Asian patients (13/30 vs 6/30, p < 0.05) on insulin were treated with a once-daily regimen. Despite these observed differences in treatment of diabetes, glycaemic control was no worse in South Asian patients when compared to their white European counterparts. South Asian diabetic patients attending hospital diabetes clinics in the UK can experience similar levels of glycaemic control to white Europeans.

Asia↗

Postinflammatory elastolysis and cutis laxa. A case report.

One of the rarest forms of cutis laxa is postinflammatory elastolysis and cutis laxa, a disease previously reported only in children in Africa and South America. This disease is characterized by an urticarial or papular eruption followed by acute destruction of elastic tissue that results in atrophy and severe disfigurement. It is distinguished from anetoderma and acquired cutis laxa by its clinical features, its occurrence in young children, and its relatively benign course. This article describes the first case of postinflammatory elastolysis and cutis laxa reported in a white child from North America.

Atrophy↗

Visual assessment of facial elastosis using photographs as a measure of cumulative ultraviolet exposure.

Because solar ultraviolet (UV) exposure is ubiquitous, it is difficult to quantify in human populations. We developed a method to index cumulative UV damage, based upon visual manifestations of facial actinic elastosis. Four photographic slides were taken of each subject's facial skin. These slides were projected on a screen and graded by consensus of 2 raters using a 5-point relative severity scale. Rating disagreements were resolved by a skilled dermatologist who acted as adjudicator. High photographic quality was maintained by standardization of camera settings, lighting, and photographic techniques. Inter- and intrarater variability in grading was minimized by training using standard slides and by practice. This index has been tested in 2 large epidemiologic studies. The method proved highly reliable and, within categories of age and tanning ability, a valid measure of cumulative UV exposure. In addition, this method appeared superior to others in speed, ease of use and cost.

Elastic Tissue↗

Irritant dermatitis from tri-butyl tin oxide and contact allergy from chlorocresol.

A shipwright developed a delayed bullous irritant dermatitis from contact with a bis-tri-butyl tin oxide (TBTO) containing antifouling paint. He subsequently developed sensitization to 4-chloro-m-cresol, a constituent of a steroid cream. No cross sensitivity to 4-chloro-3,5 xylenol was seen. Low concentrations of 4-chloro-m-cresol in pet. may elicit a true positive reaction. TBTO is a strong irritant which will produce delayed bullous reactions in industrial use and on patch testing at 0.1% aqueous.

Adult↗

Cutaneous graft-versus-host reaction: prognostic features seen by light microscopy.

Acute graft-versus-host disease (GVHD) is a severe complication of bone marrow transplantation. The diagnosis may be made and its course followed by serial skin biopsies. The degree of epidermal change has been used as a guideline in grading each biopsy, but great variation may be found within each grade, especially grade 2 (basal cell vacuolization and dyskeratosis). To find a histologic parameter that is prognostic of more severe acute GVHD, we examined retrospectively the serial biopsies of 54 patients. When we studied early cutaneous graft-versus-host reaction (GVHR), represented by the grade 2 biopsies, the number of dermal and epidermal mononuclear inflammatory cells correlated positively with the probability of developing more severe acute GVHD. In addition, the patients who had more severe acute GVHD tended to have an earlier appearance of cutaneous histologic changes. None of the other histologic parameters examined in these grade 2 biopsies were found to be predictive of GVHD progression. In addition, no histopathologic parameters in these grade 2 biopsies were predictive of the subsequent development of chronic GVHD.

Biopsy↗

Industrial exposure to organophosphorus compounds. Studies of a group of workers with a decrease in esterase-staining monocytes.

When an automated counting instrument using an esterase stain was employed, decreased monocyte counts were observed in a group of process workers exposed to organophosphate esters. Their monocyte counts were not found to be depressed with manual counting or with an automated counter using another staining method. The apparent depression was transient. In these workers and a comparison group, theoretical adverse consequences of decreased monocyte esterase and also possible changes in other esterases were explored. No anergy was seen with mumps or staphylococcal phage lysate hypersensitivity skin tests. Histology of the mumps reaction was similar in both groups. The depressed monocyte counts were significantly associated with a mild reduction in erythrocyte cell acetylcholinesterase, but no reduction was seen in plasma pseudocholinesterase or lymphocyte neurotoxic esterase.

Adult↗

Etiology of viral hepatitis in American soldiers.

To define better which types of hepatitis are prevalent among American soldiers, the authors studied 413 separate episodes of acute viral hepatitis among 412 soldiers admitted to US Army hospitals during 1978-1979. Most soldiers (68.8%) had acute hepatitis B (estimated annual hospitalization rate: 5.41/1000 soldiers in West Germany, 2.51/1000 in South Korea, less than 1/1000 in the United States). Subtype ayw was predominant in Germany, whereas adr was predominant in South Korea. Hepatitis B was more often associated with contact history or parenteral use of drugs in West Germany than in South Korea (p less than 0.001). Non-A, non-B hepatitis accounted for 27% of cases in West Germany (2.16/1000), but only 3% in South Korea (0.11/1000); hepatitis A only 15% in South Korea (0.48/1000) and 1% in West Germany (0.08/1000). These findings indicate that hepatitis B is the most prevalent form of viral hepatitis among US soldiers worldwide but also suggest substantial differences in the epidemiology of this infection in South Korea and West Germany. Such data will be useful in developing hepatitis B immunization policy within the military.

Adult↗

Systemic sarcoidosis presenting with a testicular nodule.

A patient presenting with the clinical and radiographic picture of pulmonary sarcoidosis was found to have a testicular nodule. Orchiectomy was done, and the pathologic specimen revealed only granulomatous inflammation. The involvement of the testis in sarcoidosis is reviewed, and recommendations are made regarding surgical diagnosis and medical treatment.

Adult↗

Quantitative level of protection offered to workers by ACGIH threshold limit values occupational exposure limits.

The details of the example or modeling methodologies used herein are not critical to the general point of this article, which advises the estimation of residual risk at the OEL by using some quantitative modeling structure. Specifically, the authors believe that an explicit attempt to gauge the level of residual risk at the OEL based on conceptual stochastic models with transparent and testable assumptions could be seen as an important enhancement to the process. This is especially true in sharing the OEL deliberations and explaining OEL decisions to the stakeholders. Indeed, if this approach is used, it is critically important to understand and continually communicate that this "cloud of uncertainty" represents model estimates in which the true risk would most likely be less than worst case estimates and could possibly be zero. It is also possible but highly unlikely that it could be higher than the worst case upper-bound estimate. The above quantitative estimation scheme represents a possible improvement that could provide a reasoned attempt on the part of the risk assessors to use rational science (i.e., conceptual models with transparent and testable assumptions) to inform all of the OEL users and stakeholders of their meaning.

Air Pollutants, Occupational↗