External Practicum-Year Residency Training in Occupational and Environmental Medicine: the University of Pennsylvania Medical Center Program.

We describe a competency-based training program that allows physicians employed full-time in occupational and environmental medicine to satisfy the supervised practicum year of training required by the American Board of Preventive Medicine (ABPM). The program is designed for trainees with greater clinical experience than the 1 clinical year required by the ABPM. To date, 25 physicians from clinic-based, academic, corporate, and government employment across most geographic regions of the United States have been admitted into the program. Most completed a master's in public health (MPH) in a distance-learning, on-job, on-campus, or executive program. The practicum-year training has been highly successful, as evidenced by improvements in resident self-assessment of competency, resident satisfaction with the training, faculty evaluation of resident performance, and success rate in the ABPM examination. The program has opened a new pathway for physicians making a mid-career shift to occupational and environmental medicine to obtain high-quality, in-depth education and board certification.

Occupational health and safety in national development--the case of Australia.

Over the last 15 years occupational health and safety has undergone a rapid transformation in Australia. This review discusses the changes, emphasizing, the sociopolitical and economic context, national developments in policy and practice, and the dialogue between the public and occupational health and safety agencies and professionals about occupational health and safety matters. First came the classical phase when activities followed the accepted hygienic, medical, and inspection traditions laid down early in the century. A phase followed in which modern legislation was introduced, new institutions were created, and research and data gathering on important issues was intensified. Finally came the current phase characterized by a performance paradigm. Emphasis was given to regulatory reform and the use of nonregulatory initiatives to facilitate better occupational health and safety.

What is the strategic value of occupational and environmental medicine? Observations from the United States and Australia.

The world of work is changing rapidly. Occupational health and safety and environmental health increasingly are seen as a joint product with goods and services, requiring line-management responsibility. This new specialty is encouraged to be strategic rather than tactical to optimize its value in the core business of industry-related medical needs. Because employers, governments, and workers bear major costs, they have a strategic interest in outcomes. Strategic opportunities exist for reduction of the impact of occupational injury and disease; stewardship of the environment, product, and process; the reduction of non-occupational health care costs; for having occupational and environmental health and safety follow best business practices and be prominent in the leadership of change; for optimizing human relations/labor policies and practices; and for meeting regulatory requirements. The strategic position of the specialty can be strengthened through discussion, dialogue and vision development, role definition, establishment and use of performance indicators, improved career structures and training, and a proactive approach to qualify initiatives, research, marketing, and strategic alliances.

Concomitant positive patch test results with standard screening tray in North America 1985-1989.

Responses to patch test substances may occur contemporaneously. Such simultaneous reactions may reflect concomitant sensitization to 2 dissimilar allergens to which concurrent exposure has taken place (e.g., ethylenediamine dihydrochloride and neomycin). It may occur when the individual has been exposed to only 1 of the substances and exhibits a response to other substances of similar chemical structure (i.e., cross-sensitization such as between para-phenylenediamine and benzocaine). Such simultaneous responses may also be chance occurrences, reflecting multiple sensitization or the result of altered response due to the "angry back syndrome". This investigation established that such concurrence of response is not uncommon and adds further documentation to the literature of these associations in patch test responses.

Skin elicitation threshold of ethylbutyl thiourea and mercaptobenzothiazole with relative leaching from sensitizing products.

We studied 3 contact sensitizers present in rubber products, ethylbutyl thiourea (EBT), 2-mercaptobenzothiazole (MBT) and 2,2-dithio-bis-benzothiazole (MBTS), to relate the amount of sensitizer eliciting allergic contact dermatitis to the quantity leaching from a product into various biological fluids: normal saline, human plasma and 3 synthetic sweat solutions of pH 5.5 to 7.5. To determine the amount of sensitizer remaining after leaching, Soxhlet extraction with acetonitrile was subsequently performed. High-performance liquid chromatography was used for chemical analysis. 12 MBT-sensitive patients were patch tested with serial dilutions of MBT and MBTS in petrolatum. A Latin Square design was used in statistical analysis of variance of the patch test results. Large amounts of thioureas leached from 2 rubber articles eliciting thiourea dermatitis, the literature suggesting that these would have been well above the elicitation threshold. Leaching of MBTS was relatively greater than MBT into most media, whereas MBT was a more potent elicitor than MBTS at equivalent concentrations. The lowest eliciting concentration of MBT in 1 subject was 0.01%. Such information should prove helpful to manufacturers in designed products that do not release allergens sufficiently to cause reactions in consumers.

Ocular and facial skin exposure to ultraviolet radiation in sunlight: a personal exposure model with application to a worker population.

A model of ocular and facial skin exposure to UVB is presented that combines interview histories of work activities, leisure activities, eyeglass wearing, and hat use with field and laboratory measurements of UV radiant exposure. Site-specific exposure is expressed as the product of personal ambient exposure, defined as the ambient exposure while an individual is exposed to sunlight, and factors that describe the ratio of site-specific to personal ambient exposure. Ocular exposure is further corrected by the UV attenuation of typical eyewear. The model was used to compute cumulative and yearly exposures in a population of 838 watermen who work on the Chesapeake Bay and are highly exposed to sunlight. The model was found to be predictive of conditions known to be caused by excessive sun exposure--skin elastosis, climatic droplet keratopathy, and squamous cell carcinoma--and has been useful in several epidemiological studies.

Association of nonmelanoma skin cancer and actinic keratosis with cumulative solar ultraviolet exposure in Maryland watermen.

To establish the relationship between ultraviolet-B radiation and squamous cell carcinoma (SCC), basal cell carcinoma (BCC), and actinic keratosis (AK), a cross-sectional prevalence survey was performed in a sample of 808 white, male watermen 30 years of age and older residing in the Eastern Shore of Maryland. A measure of personal cumulative ultraviolet-B exposure was determined for each subject from data collected through interviews and field and laboratory measurements. A personal interview elicited skin type, medication history, and other factors. Clinical diagnoses and histologic confirmation were done for current and previously removed skin tumors. The ratio of subjects with SCC to subjects with BCC was approximately 1:1; however, the ratio of BCC to SCC was 1.25:1 because BCC cases were more prone to multiple lesions. Watermen with SCC or AK but not BCC had higher average annual ultraviolet-B doses than age-matched controls. This was particularly marked in watermen younger than 60 years of age. Logistic regression showed that an older age, childhood freckling, and blue eyes significantly increased the risk of the development of all three types of skin tumor. Ease of sunburning was associated with BCC and AK, but not with SCC. Watermen in the upper quartile of cumulative ultraviolet-B exposure had a 2.5 times higher risk for the development of SCC when compared with the lower 3 quartiles. This suggests that high levels of ultraviolet-B exposure are important in SCC occurrence. The risk of AK developing was 1.5 times higher for those whose cumulative ultraviolet-B exposure exceeded the median. The relationship of BCC to cumulative ultraviolet-B exposure was not clear and this suggests that different etiologic mechanisms operate for SCC and BCC.

Methylchloroisothiazolinone-methylisothiazolinone reactions in patients screened for vehicle and preservative hypersensitivity.

More than 1100 patients were tested with methylchloroisothiazolinone-methylisothiazolinone, 100 ppm, in aqueous and petrolatum-based patch test materials from 1985 to 1987 by members of the North American Contact Dermatitis Group. Thirteen reactions to the aqueous materials and 10 to the petrolatum-based materials were observed. Irritant reactions were infrequent, and about half the reactions were deemed relevant. From 1984 to 1985, patch tests with this substance at a concentration of 250 ppm in petrolatum were conducted. Thirteen persons were identified as allergic, but three others were sensitized by the patch test procedure. Sensitization as not observed in tests with aqueous or petrolatum-based substance at a concentration of 100 ppm, and this concentration appears to be the best compromise between safety and sensitive detection of allergy. Use tests are helpful but not infallible as a guide in establishing relevance with methylchloroisothiazolinone-methylisothiazolinone. Wash-off products are frequently well tolerated by patients with positive reactions to this substance.

Quantitative carcinogenesis in man: solar ultraviolet B dose dependence of skin cancer in Maryland watermen.

Skin cancer is the most common form of cancer in humans and occurs primarily on sun-exposed areas of the body. In a study of 808 Caucasian Maryland watermen, we examined the prevalence of nonmelanoma skin cancer in relation to age and exposure to solar ultraviolet B (UVB) radiation. For each study subject, the exposure to solar UVB radiation for each year of life after the age of 16 years was calculated. We obtained the data for this analysis by combining a detailed occupational history with laboratory and field measurements. Prevalence of the three major types of nonmelanoma skin neoplasms was analyzed: squamous cell carcinoma (SCC), basal cell carcinoma (BCC), and actinic keratosis (AK). Average annual exposure to UVB radiation was strongly correlated with the prevalence of SCC, but not with the prevalence of BCC or AK. This finding is consistent with dose saturation (plateau in dose-response relationship) for the induction of BCC and AK in humans with high annual exposure to UVB radiation. In addition, two small groups of apparently hypersusceptible individuals were present in the population. One group had SCC despite low annual exposure to UVB radiation, and the other group had multiple skin cancers despite average exposure to UVB radiation.

Corneal changes associated with chronic UV irradiation.

The association between exposure to UV radiation and corneal disease was investigated in 838 watermen who work on the Chesapeake Bay, Maryland. Individual ocular exposure was calculated by combining a detailed occupational history with laboratory and field measurements. Pterygium was found in 140, climatic droplet keratopathy in 162, and pinguecula in 642. Logistic regression analysis showed that pterygium and climatic droplet keratopathy were significantly associated with a broad band of UV radiation exposure (UV-B, 290 to 320 nm; A1, 320 to 340 nm; and A2, 340 to 400 nm), but the association with pinguecula was weaker. Simple measures such as wearing a hat or spectacles protect the eye and could potentially reduce the amount of pterygium and climatic droplet keratopathy attributable to UV radiation exposure.

Cyclobuta-dithymidine induction by solar-simulating UV radiation in human skin: II. Individual responses.

The purpose of this study was to examine cyclobuta-dithymidine (T*T) photoproduct induction and persistence in human skin exposed in situ to simulated solar UV radiation. Small areas of untanned skin in nineteen individuals were exposed using a solar UV apparatus that simulates both the spectrum and intensity of the UV portion of summer midday sunlight at 39 degrees N latitude. The equivalent of approximately 60 min of sunlight exposure (72KJ/m2) was administered, and T*T photoproducts were quantitated by enzyme-linked immunosorbent assay (ELISA) of DNA extracted from skin punch biopsies. Net yields of T*T photoproducts were determined in 10 individuals, with the majority (7 of 10) between 0.02 and 0.12 T*T per kilobase (Kb). The three remaining individuals had higher levels of photoproducts but were not unusually sensitive to solar UV as determined by minimal erythema dose (MED). Percentage loss of T*T photoproducts 4 h after exposure was determined in nine individuals to be 80.2 +/- 14.0%.

Cigarette smoking and risk of nuclear cataracts.

The current study was undertaken to assess the relationship of smoking to the risk of lens opacities. The risk was evaluated separately for nuclear and cortical opacities and for both types together. We studied 838 watermen in Maryland by detailed ocular examination for the presence and severity of each cataract type. All subjects were interviewed regarding smoking history, and a cumulative smoking dose was calculated. The results suggest a significantly increased risk of pure nuclear opacities associated with cigarette smoking. The increase in smoking dose was associated with increasing severity of nuclear opacity. The risk of nuclear opacities increased with increasing cigarette dose and decreased if the subject had quit smoking. The effect of smoking was most striking in those less than 80 years old. No increased risk of nuclear opacities was observed with earlier age when smoking started, after adjusting for dose and cessation of smoking. Further investigations are warranted on the biochemical and physical damage to the nucleus of the lens from smoking cigarettes.

Prevalence and relevance of allergic reactions in patients patch tested in North America--1984 to 1985.

Between Jan. 1, 1984, and May 1, 1985, 1199 patients with suspected allergic contact dermatitis were patch tested with 32 "standard" allergens, 707 patients with 19 "vehicle and preservative" allergens, and 613 patients with 10 "special study" allergens. Ten dermatologists representing nine geographic centers collected and analyzed data with the use of the American Academy of Dermatology's mainframe computer in Evanston, Illinois. The most common sensitizers identified were nickel, p-phenylenediamine, quaternium-15, neomycin, thimerosal, formaldehyde, cinnamic aldehyde, ethylenediamine, potassium dichromate, and thiuram mix. Each positive reaction was assessed for its clinical relevance.

The irritancy and allergenicity of 2-n-octyl-4-isothiazolin-3-one (Skane M-8), with recommendations for patch test concentration.

Preparations of 2-n-octyl-4-isothiazolin-3-one (Skane M-8) at 1000 p.p.m. a.i. and 500 p.p.m. a.i. in pet. induced allergy in a cumulative insult human patch test. Challenge patch testing using 250 p.p.m. a.i. Skane M-8 elicited allergy in 6 out of 6 sensitized individuals. Sensitized individuals did not cross react with Kathon biocide, (Kathon CG), a mixture of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one. All pretrolatum preparations to which Tween 85 was added at 2.5% produced mild irritation in cumulative insult patch tests, but no irritation was observed with Tween 85 at 0.625%. We conclude that Skane M-8, 250 p.p.m. a.i. with Tween 85 0.625% in petrolatum is appropriate for patch testing for Skane M-8 allergy.

Follow-up of subjects who developed chloracne following TCDD exposure at Seveso.

Three follow-up surveys from 1976 to 1985 were carried out on 193 subjects who developed chloracne following the Seveso accident (1976). A comparison group, age and sex matched, was selected randomly from the list of residents of the town of Varedo (in the same health district but out of the dioxin-contaminated zone). At each follow-up a questionnaire was administered and biochemical tests, skin examination, and electrophysiologic measurements were performed. Biochemical indicators of hepatic function and nerve conduction studies did not show significant differences either between groups or for temporal trends. Chloracne was shown to be clinically reversible: all the chloracne cases (except for one subject) clinically recovered by 1983. The discrepancy between our results and those from other previous experiences can be related to a different type of exposure, the young age of the target population, and the interval since exposure.

Polychlorinated biphenyl congeners in adipose tissue lipid and serum of past and present transformer repair workers and a comparison group.

The concentrations of individual PCB's were determined in both serum and adipose tissue lipid from 35 transformer repair workers currently exposed to PCBs, mainly Aroclor 1260, 17 previous transformer repair workers, and 56 comparison workers never occupationally exposed to PCBs. The analysis used fused-silica capillary gas chromatography with electron capture detector (FSCGC/ECD) and FSCGC with negative ion chemical ionization mass spectrometry to verify PCB congener levels. Eighty-nine PCB peaks were identified and confirmed. More congeners were detected in adipose tissue. In serum approximately 50% of peaks were below the level of detection. Statistical techniques to account for left and interval censoring allowed comparison of concentration distributions even where data were incomplete. We found that unquantifiable levels were unlikely to contribute substantially to the true values for total [PCBs] over and beyond the contribution of the measured values. However, the total serum [PCBs] determined by FSCGC/ECD greatly exceeded that from standard packed cell gas chromatography (PCGC/ECD). The underestimation was less marked for adipose samples. In serum the total [PCBs] was highest in currently exposed workers and lowest in unexposed workers, with past-exposed workers clearly intermediate. In adipose tissue [PCBs] in the currently exposed group was much higher than in the other two groups, in whom the distribution of results was broadly similar. In all worker groups hexachlorinated and heptachlorinated species predominated followed by octachlorinated and pentachlorinated. The relative distribution of individual PCB congeners in the three groups was similar although the amounts varied. The seven major peaks in serum and adipose tissue were 2,3,5,6,3',4',5'/2,3,4,5,2',4',5' hepta-CB; 2,3,4,2',3',5' hexa-CB; 2,4,6,3',4',5'/2,4,5,2',4',5'/2,3,4,5,2',5' hexa-CB; 2,3,4,5,2',3',4' hepta-CB; 2,3,4,5,2',3',5',6'/2,3,4,5,6,2',3',5', octa-CB; 2,4,5,3',4',/3,4,5,2',3' penta-CB; and 2,3,4,2',3',4'/2,3,5,6,2',4',5'/2,3,4,5,2',4',6' multi-CB. The distribution of PCB peaks in our populations differs from that in capacitor workers (exposed to less highly chlorinated PCBs) and from Yu-Cheng patients suggesting differing toxic potentials from PCBs in these three circumstances.

Effect of ultraviolet radiation on cataract formation.

To investigate the relation of ultraviolet radiation and cataract formation, we undertook an epidemiologic survey of 838 watermen (mean age, 53 years) who worked on Chesapeake Bay. The annual ocular exposure was calculated from the age of 16 for each waterman by combining a detailed occupational history with laboratory and field measurements of sun exposure. Cataracts were graded by ophthalmologic examination for both type and severity. Some degree of cortical cataract was found in 111 of the watermen (13 percent), and some degree of nuclear cataract in 229 (27 percent). Logistic regression analysis showed that high cumulative levels of ultraviolet B exposure significantly increased the risk of cortical cataract (regression coefficient, 0.70; P = 0.04). A doubling of cumulative exposure increased the risk of cortical cataract by a factor of 1.60 (95 percent confidence interval, 1.01 to 2.64). Those whose annual average exposure was in the upper quartile had a risk increased by 3.30 (confidence interval, 0.90 to 9.97) as compared with those in the lowest quartile. Analysis using a serially additive expected-dose model showed that watermen with cortical lens opacities had a 21 percent higher average annual exposure to ultraviolet B (t-test, 2.23; P = 0.03). No association was found between nuclear cataracts and ultraviolet B exposure or between cataracts and ultraviolet A exposure. We conclude that there is an association between exposure to ultraviolet B radiation and cataract formation, which supports the need for ocular protection from ultraviolet B.