COOPERATIVE EXTENSION UNIVERSITY OF CALIFORNIAENVIRONMENTAL TOXICOLOGY NEWSLETTER

COOPERATIVE EXTENSION UNIVERSITY OF CALIFORNIA
ENVIRONMENTAL TOXICOLOGY NEWSLETTER

This edition of the Environmental Toxicology Newsletter contains excerpts taken from recent reports in the MMWR that covered skin and respiratory toxicity. Most of the respiratory reports were in one way or another connected to smoking and its propensity to cause lung cancer and other pulmonary diseases. One report on the declining incidence of lung cancer in males is encouraging while another report on the numbers of high school smokers is alarming. I would like to particularly point out the National Cancer Institute cancer prevention and control objectives for the year 2000 (page 3) and the statement in the first article that "smoking is presently the largest single cause of preventable morbidity and mortality in the United States".

An underlying theme of all the articles is the fact that most, if not all, pulmonary and skin toxicities can be prevented by using proper protective equipment. This applies to human manufactured chemicals such as pesticides and industrial chemicals, and natural toxicants such as fungal spores. The importance of using protective equipment cannot be over-emphasized.

From July 1983 through December 1984, as part of a health-risk survey, information was obtained from 11,657 Rhode Island public high school students about their cigarette smoking practices. Overall, 22.3% of these students reported that they smoked cigarettes. Cigarette smoking increased by grade and was more common among females (26.5%) than among males (17.5%). The difference between females and males was due primarily to a larger proportion of females who reported smoking less than one pack per day.

Editorial Note: Cigarette smoking is presently the largest single cause of preventable morbidity and mortality in the United States. The prevalence of smoking has slowly declined over the past 2 decades, and over 30 million Americans have quit smoking since the first Surgeon General's report on smoking and health was released in 1964. It has been estimated that, from 1964 to 1978, more than 200,000 premature deaths were prevented because some people stopped smoking, and others did not start. Nevertheless, approximately one-third of the U.S. adult population still smokes cigarettes, and there is some evidence that the prevalence of smoking is actually increasing among young white females.

The Rhode Island data confirm that smoking among high school students is more common among young females than young males. Continued efforts to prevent the onset of smoking among young people are necessary. Because of the growing use of smokeless tobacco among children and adolescents, these efforts should also be directed toward preventing the use of smokeless tobacco products in this age group.

II. Deaths due to Chronic Obstructive Pulmonary Disease and Allied Conditions

In 1984, chronic obstructive pulmonary disease (COPD) and allied conditions were the eleventh leading cause of years of potential life lost before age 65 (YPLL) in the United States, accounting for 123,000 YPLL. The category "COPD and allied conditions" is composed of a variety of diseases, including bronchitis (inflammation of the bronchi), emphysema (abnormal increase in size of the smallest bronchioles resulting in inability to expel air properly from the lungs), asthma, bronchiectasis (abnormal dilation of one or more of the bronchi), extrinsic allergic alveolitis (inflammation of the alveoli, the areas of the lung where actual gas exchange takes place), and chronic airway obstruction not specifically labeled as one of the preceding conditions. Chronic airway obstruction was responsible for the most deaths and YPLL in 1983. Because the causes of death in this category are probably the same as in the bronchitis and emphysema category, for this report, those three categories are combined as COPD.

Editorial Note: COPD is an important health problem for Americans, causing an estimated 4.7 million hospital days per year and $6.5 billion in direct and indirect costs. Smoking accounts for 80%-90% of COPD mortality for both men and women. The total death rate and YPLL rate are higher for men than for women and higher for whites than for other races. These findings probably reflect previous differences in smoking patterns among these groups. The risk of COPD increases with the dose of exposure, i.e., number of cigarettes smoked per day, and the duration of smoking. Within a few years after beginning to smoke, smokers have a higher prevalence of abnormal function of the small airways than nonsmokers, and the severity of dysfunction increases with years of smoking. Smoking cessation leads to a decreased risk of mortality; however, even 20 years after cessation, the risk of death from COPD for former smokers is not as low as for persons who have never smoked.

The Surgeon General's report in 1979 indicated that inhaled tobacco smoke can trigger or aggravate asthmatic symptoms in persons with asthma. This offers support for the cessation of smoking and the avoidance of passive smoke exposure in asthmatic individuals.

III. Decrease in Lung Cancer Incidence among Males -- United States, 1973-1983

Both incidence and mortality due to lung cancer have been decreasing for men under 45 years of age since at least 1973, and for men between 45 and 54 years of age, since 1978. For men over 54 years of age, the rates have leveled. Data for black males show age-adjusted incidence rates that are approximately 50% higher than for whites; however, the trends in rates are similar in the two groups. Lung cancer mortality data for U.S. men have leveled to an age-adjusted rate of 71.2 in 1983. Mortality rates for black males have leveled to an age-adjusted rate of 97.3 in 1983. Because survival from lung cancer is poor, it is expected that decreases in lung cancer mortality will be noted in the 1984 data.

Lung cancer incidence and mortality rates for females continued to increase markedly during the same period. Age-adjusted incidence and mortality rates of 32.6 and 24.3, respectively, represented over 41,000 new cases of lung cancer and over 35,000 deaths among U.S. women in 1983.

Editorial Note: Approximately 15% of all invasive cancers diagnosed annually are cancer of the lung, and roughly 149,000 new cases and 130,000 deaths are expected in 1986. It has long been established that cigarette smoking is the primary cause of lung cancer in the United States. Smoking prevalence among adult males in the United States decreased from 52% before the Surgeon General's report to about 35% in 1983. Such considerable decreases in smoking prevalence have not been observed among females; the smoking prevalence among women was 34% in 1965 and 29% in 1983. Unfortunately, the percentage of smokers who smoke 25 or more cigarettes per day was 13% in 1965 and 25% in 1980, suggesting that the bulk of smoking cessation may have been among lighter smokers.

Recently, the National Cancer Institute defined cancer prevention and control objectives for the year 2000, which include the following risk-factor reduction objectives: (1) the proportion of adults who smoke should be reduced to 15% or less; and (2) the proportion of children and youth aged 12-18 years who smoke should be reduced to 3% or less. The attainment of these goals will result in more than a 40% reduction in deaths due to lung cancer than would be expected if the current rates of smoking prevalence continue into the next century.

IV. Acute Respiratory Illness Following Occupational Exposure to Wood Chips -- Ohio

The inhalation of organic dust contaminated with microbes has been recognized as an occupational hazard for persons who work with decomposing vegetable matter. An outbreak of illness caused by such inhalation occurred in Ohio in 1983. The investigation that followed is described below.

On June 21, 1983, five employees at a municipal golf course became ill with an influenza-like syndrome within hours after manually unloading a trailer truck full of wood chips. Physicians from the city health department examined and tested all golf-course employees who had helped in the unloading and requested assistance from the National Institute for Occupational Safety and Health in evaluating the outbreak. On June 24, a questionnaire was administered to those employees exposed to wood chips, and their medical records were reviewed. The investigators inspected the unloaded wood chips, collected samples, and interviewed the wood chips' vendor.

The wood chips were brought to the golf course in an enclosed, 40-foot trailer. Eleven employees participated in some aspect of the unloading process. Although fresh chips had been ordered, the vendor included old chips that had been stored in the front of the truck for approximately 1 year. Unloaded chips from the front were grossly moldy, and cultures revealed a wide variety of mesophilic (organisms that grow well at 20-25o C) and thermophilic (organisms that grow best above 50o C) bacteria and fungi.

All five ill employees had worked in very dusty conditions without respiratory protection while unloading the front of the trailer on the afternoon of June 21. The time from beginning of unloading until onset of illness ranged from 4 hours to 16 hours (median 13 hours). None of the workers were hospitalized, but one reported to a local emergency room, and two were too ill to work the following day. Within 48 hours, symptoms were very much improved; within 72 hours, all affected workers had completely recovered.

The other six employees included three who had unloaded fresh chips from the back of the trailer on the morning of June 21, one supervisor who had briefly checked on the unloading process, and two workers who finished unloading the front of the trailer on the morning of June 22 but wore air-purifying respirators. Thus, all five workers who had unloaded the moldy wood chips without respiratory protection became ill, compared with none of the other six workers.

On the basis of clinical and epidemiologic evidence, the investigators concluded that this episode probably represented an outbreak of self-limited, acute toxic reaction associated with inhalation of large amounts of dust heavily contaminated with microbial toxins from decomposing vegetable matter.

Editorial Note: In 1975, an apparent toxic pulmonary illness was reported among 10 farmers who became ill several hours after removing moldy silage. The authors of that report referred to the illness as "pulmonary mycotoxicosis" because the etiology presumably involved toxic components of inhaled fungal organisms. Others have recognized an apparently identical syndrome but have applied other names to it. Thus, it has been variously referred to as (1) "silo unloader's syndrome" to contrast it with silo filler's disease, a toxic pulmonary edema following inhalation of the oxides of nitrogen in freshly filled silos (see Environmental Toxicology Newsletter Volume 3 Number 2); (2) "precipitin test negative farmer's lung" to emphasize its clinical similarities to and its pathogenetic differences from farmer's lung disease, an immunologic lung response to microbial antigens in moldy hay; and (3) "organic dust toxic syndrome" (ODTS), a generic designation to emphasize that mycotoxin exposure is not a necessary prerequisite and that the syndrome is not restricted to either silo exposures or farming occupations. A striking similarity has been recognized between ODTS and "mill fever" in cotton textile workers, "grain fever" in grain elevator workers, and "humidifier fever" in building occupants exposed to air from highly contaminated ventilation systems. Similar to the current report, moldy wood chips were etiologically linked to symptoms of ODTS in individuals exposed to dust from wood chips that had been stored in basements as a fuel source for wood-burning furnaces.

Epidemiologically, ODTS often occurs in small outbreaks, with illness affecting all or most individuals who have had intense exposure to microbially contaminated vegetable dust. The syndrome is clinically characterized as an acute febrile illness with respiratory symptoms; onset usually occurs 4-12 hours after exposure. General malaise (uneasiness), headache, and cough are common symptoms, while dyspnea (difficult breathing) is variably present.

With removal from exposure, ODTS is a self-limited illness, occasionally resolving within 24 hours, often within several days, and sometimes only after a few weeks. To date, no deaths have been reported, and there is no evidence for residual pulmonary fibrosis. Some individuals, however, have been hospitalized with severe symptoms, and a few have undergone diagnostic bronchoscopy and lung biopsy.

ODTS probably occurs much more frequently than is currently recognized. Only serious solitary cases or those that occur in suspicious clusters are likely to come to medical attention, and when a history of environmental exposure is elicited, these are often misdiagnosed by physicians as silo filler's disease or farmer's lung disease. Because the incidence, etiologic agent(s), and pathogenesis of ODTS remain unknown, physicians are encouraged to report to appropriate health authorities any influenza-like illness following intense exposures to organic dust. Based on current understanding, symptomatic treatment alone should suffice. Prevention measures should include storing vegetable matter in a way that limits microbial growth and wearing appropriate respiratory protection when intense exposure to organic dusts cannot be avoided.

Editorial Note: As an underlying cause of death, malignant neoplasms ranked second in the United States in 1983, accounting for 442,986 deaths, or about 22% of all deaths. Of these deaths, 36% occurred among persons under 65 years of age. In 1986, 472,000 cancer deaths are expected to occur among U.S. residents, 54% among males. Almost 1.4 million newly diagnosed cancer cases are expected, about one-third of which would be due to nonmelanotic skin cancers and carcinomas in situ. For a child born in 1985, the probability at birth of eventually developing cancer (excluding nonmelanotic skin cancers) is about 33%, and the probability of eventually dying of cancer, about 20%.

Background. A worker's skin is directly exposed to the occupational environment and is susceptible to a large number of dermatologic injuries and other conditions. Complete data on the extent and cost of dermatologic injuries are not available; however, dermatologic conditions other than injuries accounted for 37% of the 106,100 occupational illnesses recorded in 1983 in the Bureau of Labor Statistics (BLS) Annual Survey of Occupational Injuries and Illnesses. Results from the BLS Annual Survey for 1972-1976 indicated that 20%-25% of all occupational dermatologic conditions resulted in lost time from work (average 10-12 lost work days).

Dermatologic Injuries. Dermatologic injuries are usually described as the immediate adverse effects on skin that result from instantaneous trauma or brief exposure to toxic agents involving a single incident in the work environment. Skin injuries may constitute 23%-35% of all injuries.

Other Dermatologic Conditions. Other dermatologic conditions ("illnesses of the skin") may also result from exposure to environmental factors or toxic agents associated with employment. However, they usually result from more sustained or cumulative exposures and involve longer intervals between exposure and occurrence of disease. These conditions include contact dermatitis, infection, acne, and skin cancer. Workers' compensation claims data from California suggest that 95% of these occupational skin conditions are either contact dermatitis (90%) or infections (5%).

The highest number of other occupational skin conditions (23,017) in 1984 occurred in the manufacturing sector; the highest incidence rate (28.5/10,000 full-time workers) involved the combined agriculture/forestry/fishing division (Table 3).

The clinical course for occupational contact dermatitis is relatively poor. In three studies, complete resolution occurred in 25% of workers affected; 50% improved but had periodic recurrences; and 25% developed persistent dermatitis as severe as or worse than the original condition. Contact dermatitis often necessitates job changes or modifications. Despite these, however, complete resolution may occur in only a limited proportion of cases.

Prevention of Work-Related Dermatologic Disorders. The most effective prevention measures are engineering controls that eliminate exposures of the skin to chemical, physical, or mechanical agents through isolation, containment, or redesign of industrial processes. Substitution of less toxic substances through chemical engineering may also be effective. Protective clothing should be selected on the basis of resistance to both chemical and physical hazards, as well as on the relative permeabilities to specific chemical exposures.

TABLE 3. Cases and incidence rate of occupational dermatologic conditions, in a segment of workers, by major industrial divisions --- United States, 1984*

Industrial division	No.	Incidence rate**
Agriculture/forestry/fishing	2,233	28.5
Manufacturing	23,017	12.3
Construction	2,456	6.6
Services	7,973	5.0
Transportation/utilities	2,114	4.3
Mining	393	4.0
Wholesale/retail trade	3,770	2.1
Finance/insurance/real estate	563	1.1

*Bureau of Labor Statistics Annual Survey.
**Per 10,000 full-time workers (2,000 employment hours/full-time worker/year).

Author Note: The high incidence of occupational dermatologic conditions seen in agriculture, forestry and fishing is most likely related to the potential for exposure to natural irritants and toxins such as poison oak. For further information about the possible causes of dermatitis in agriculture see the Environmental Toxicology Newsletter Volume 3 Number 1, September 20, 1982.

In May 1986, a dermatitis outbreak occurred among orange pickers employed by a packer in Tulare County, California. The Worker Health and Safety Branch of the California Department of Food and Agriculture (CDFA) notified the California Department of Health Services of the outbreak on May 12 after it had been reported by the Tulare County Agricultural Commissioner's office.

Physicians for 114 (58%) of the 198 orange pickers filed Pesticide Illness Reports (PIRs) for pesticide-induced dermatitis (PIRs are required in California for cases of suspected pesticide illness and are considered to represent an official case count). Onset of dermatitis occurred between April 30 and May 9, 1986, following exposures to OMITE-CRR (Uniroyal Chemical Co.) beginning April 26. Dermatitis incidence rates for each of six work crews ranged from 23% (6/26) to as high as 78% (28/36).

Additional investigation included on-site observations and interviews with three of the six work crews (88 workers), collection of spraying and work histories for January 1-May 12 relating to all 80 orchards harvested by the crews, and leaf residue degradation data. On-site observations revealed that the orange pickers frequently leaned into dense foliage to harvest oranges; thus, direct contact with foliage plus possible exposure to pesticide residue occurred. The interviews revealed that the dermatitis occurred commonly in the exposed areas of the neck (81%) and the chest (42%). Most of the pickers reported that dermatitis started with burning, redness, and itching. In many cases, the lesion progressed to small papules (small, solid elevated lesions like the initial stages of acne), vesicles (fluid filled, elevated lesions like poison oak dermatitis) with weeping and crusting, exfoliation (sloughing of skin from affected areas), and hyperpigmentation (darkening of the affected areas). One-third of the interviewed workers reported exfoliation, indicating severe dermatitis. Thirty-four percent reported eye irritation, for which 8% received medical treatment.

The Tulare County Agricultural Commissioner considered the miticide OMITE-CRR the likely cause of the dermatitis, providing a working hypothesis. An analysis based on the interviews, PIR reports, and leaf residue sampling information concluded: (1) no cases of dermatitis occurred in the interval immediately before the harvesting of fields sprayed with OMITE-CRR; (2) the highest correlation in a predicted direction was between residue-hours of OMITE-CRR (a measure combining estimated leaf residue multiplied by hours spent harvesting) and dermatitis (Rs = 0.60). Simple cumulative hours of OMITE-CRR exposure produced a slightly lower correlation (Rs = 0.54). No positive correlation was found between cumulative hours of exposure to CARZOLR (NOR-AM), the only other pesticide used extensively in the orchards, and dermatitis (Rs = -0.02). A measure of "OMITE-CRR + CARZOLR" interaction correlated less highly with dermatitis (Rs = 0.37) than did the OMITE-CRR exposure alone. Cumulative hours of exposure to other pesticides correlated inversely with dermatitis (Rs = -0.71); and (3) no violations of preharvest intervals (the interval between last application and harvest) or application levels (lbs/acre) were noted for any of the pesticides used on the orchards.

The workers were treated by local physicians, and symptoms improved. The county instituted an emergency 14-day reentry interval for fields with OMITE-CRR, extending the California label instructions (1-day reentry, 7-day preharvest). This reentry interval was later extended to 28 days, then to 35 days. Subsequently, the manufacturer withdrew the California registration for OMITE-CRR.

Editorial Note: This is the largest pesticide-induced dermatitis outbreak recorded in California. Because that state requires pesticide illness reports, the outbreak and its causal factors were quickly identified so that appropriate interventions could be made.

OMITE-CRR, the pesticide identified in the dermatitis outbreak, is a noncholinesterase-inhibiting miticide of low systemic toxicity but with known dermal irritation qualities. Its active ingredient is 30% propargite, 2-(4-(1,1- dimethylethyl)phenoxy)cyclohexyl-2-propynyl sulfite. The manufacturer had recently reformulated it to prevent leaf burn in citrus trees by coating the propargite granules in an inert ingredient that apparently slowed degradation. The CDFA continued the 7-day preharvest interval for the new formulation that was previously established for the earlier formulation (OMITE-30WR).

Next to sulfur, propargite is the second most frequently reported pesticide in the California PIRS as a probable cause of dermatitis among agricultural workers. During a 12-year period from 1974 through 1985, 506 cases of dermatitis associated with exposure to propargite were recorded, compared with 677 for sulfur. Certain California counties require a 3-day field reentry interval for sulfur. For one other pesticide, anilazine (DYRENER), California requires a 48-hour reentry interval based on dermal effects.

Protective clothing is usually neither practical nor effective for preventing skin exposure to pesticides in field crop workers. Impermeable clothing promotes the potential for heat stress, and monitoring skin exposure by dermal patches beneath permeable clothing has demonstrated that substantial skin exposure to residues still occurs. The most effective strategy for control is regulation through establishment of safe reentry intervals for skin exposure. The investigation reported above is one of the few instances where residue levels were sufficiently documented at the time of the dermatitis outbreak to establish a safe reentry level.

Hazard Evaluation System and Information Service (HESIS) - 415- 540-3014 for health information (you may call collect). For other business, call 415-540-2115. California Departments of Health Services and Industrial Relations in Berkeley.

Community Toxicology Unit - 415-540-3063
California Department of Health Services