Vol. 3 No. 2



I. Silo Fillers Disease
II. Oral Contraceptives and Cancer Risk
III. Formaldehyde
IV. Bonemeal
V. Rash Illness Associated with Gypsy Moth Caterpillars
VI. Residue Avoidance Program

Introduction: This newsletter contains information extracted from various sources that should be of interest to many readers.

I. Silo-Filler's Disease in Rural New York

On September 18, 1981, at a farm in Mohawk, New York, a 39-year-old farmhand was overcome while climbing up the chute of a recently filled concrete stave silo and later died of presumed silo-filler's disease. The case report follows. In the preceding 10 days, the farm owner had filled this silo with Sudex grass and chopped corn silage. On September 18, he asked a farmhand to climb up the unloading chute inside the silo and toss out fresh silage. When the farmhand climbed the chute, he became short of breath and confused and had to descend. He made a second attempt but again had to climb down and was noted to be cyanotic (blue), pale, and diaphoretic (sweating).

At a local hospital, the examining physician noted cyanosis and respiratory distress...The patient was moved to the intensive care unit, where a tentative diagnosis of pneumonia was made. He became agitated, would not wear an oxygen mask, and remained in shock. Five hours after admission, he experienced cardiopulmonary arrest and died despite vigorous efforts to resuscitate him.

Post-mortem examination the next day showed grossly edematous lungs with pleural effusions(fluid in chest cavity) on both sides.

The farmer reported that, following his farmhand's illness, he had turned on the silo blower and sent another worker up to toss out corn; no ill effects had occurred.

Several factors support the diagnosis of silo-filler's disease, an illness caused by the inhalation of nitrogen oxides: i.e., rapid onset of symptoms following a recent filling of the silo and histology classic for toxic exposure.

Editorial Note: The case outlined above is typical for massive exposure to nitrogen oxides. Silo-filler's disease represents an occupational hazard associated with ensiled crops.

N204 is colorless and odorless, and exposure can occur without warning. If undetected by smell or sight, the potent nitrogen oxides may be inhaled deep into the lungs, where contact with the mucosal moisture produces nitric acid, which burns the airways, respiratory bronchioles, and alveoli.

In fatal exposures, vascular collapse and the outpouring of serum rapidly produce shock and death. In another clinical course associated with silo-filler's disease, exposure causes cough and chest tightness. Although these conditions clear spontaneously, illness may return in three weeks with severe symptoms of fever, chills, and shortness of breath.

Fatal and serious exposures to nitrogen oxides are not unique to farming but have been reported in association with arc and acetylene welding, burning cellulose nitrate, and dynamite blasting.

It is possible to prevent this type of exposure in the farm industry if farmers are aware of the following dangers and use the suggested safety measures: 1) Silos begin to produce NO within 4 hours after filling, and no one should enter or come in close contact with a recently filled silo. 2)Some crops (oats, corn) produce more NO2 than others, and heavily fertilized crops, cloudy conditions, and rain raise the risk of NO2 production. 3) Although NO levels are generally low and within a safe range after 2 weeks, dangerous amounts may remain for months if the silo has not been opened. 4) If possible, enclosed areas should be ventilated for 20 minutes before anyone enters, and individuals should be equipped with a full-face mask and an air supply.

MMWR, Vol. 31/No. 28, July 23, 1982.

Author Note: Silo fillers disease is usually not a problem when silage is made in bunk silos, however nitrogen oxides also may form in bunk silos. The two hazardous oxides of nitrogen produced in silage, NO and N O , are both heavier than air and thus will tend to "flow" downhill. Livestock have been poisoned by such movement of the gases into animal quarters.

II. Oral Contraceptives and Cancer Risk

An initial analysis of an ongoing, multicenter case-control study indicates that women who have used oral contraceptives are approximately half as likely to develop ovarian and endometrial cancer as women who have never used them and that, despite previous concerns, contraceptive use does not appear to increase a woman's risk of breast cancer.

There was no evidence that long-term oral contraceptive use of more than 10 years or oral contraceptive use that began 16 or more years ago, shortly after oral contraceptives were introduced in this country, increased the risk of breast cancer. Furthermore, there was no indication of any increased risk of breast cancer due to oral contraceptive use for high-risk women such as those with family histories of breast cancer or with previous biopsies for benign breast disease. Similarly, there was no evidence of an increased risk of breast cancer for women who used oral contraceptives before their first pregnancy.

MMWR, Vol. 31/No. 29, July 30, 1982

III. Formaldehyde

Now that the Consumer Produce Safety Commission has banned urea formaldehyde foam as an insulation material, the Food and Drug Administration issued the following "talk paper" on June 17, 1982.

The Food and Drug Administration has received the final report of a formaldehyde inhalation study on Laboratory Animals. The object of the study, reported by the chemical Industry Institute of Toxicology, was to determine the possible adverse effects of inhaling formaldehyde vapor in various concentrations.

The study involved 720 mice and 720 rats, divided into three groups of 240 each (120 males and 120 females). Each group was exposed repeatedly for six hours per day, five days per week for two years to formaldehyde vapor in concentrations of 15, 6 or 2 parts per million. A control group of 240 mice and 240 rats was not exposed to formaldehyde vapor.

In the 15 PPM exposure group squamous cell carinomas (malignant cancers of the skin) of the nasal cavity were observed in two mice and 103 rats. In the 6 PPM exposure group two rats developed carcinomas in the nasal area. No nasal tumors were observed at a dose of 2 PPM in mice or rats. None was found in the control group.

Due to the irritating properties of formaldehyde for humans, a single exposure to 15 PPM of formaldehyde vapor would be immediately intolerable. People would flee an area with that much vapor because of the smell and irritation. Some people may be able to tolerate a single exposure to 6 PPM for 10 minutes. A single exposure to 2 PPM would be uncomfortable and cause a person's eyes to water.

On the basis of current data, FDA has concluded that no regulatory action against the use of formaldehyde in the products it regulates is necessary at this time to protect the public health. The potential formaldehyde exposure from FDA-regulated products is very low.

IV. Bonemeal

June 12, 1981 - The Food and Drug Administration today announced results of a nationwide survey of Bonemeal products to determine their lead content.

An analysis of 77 samples of bonemeal powder, capsules and tablets collected from 40 known Manufacturers and several importers showed an average lead level of 4.4 parts per million (PPM), with a range of 0.045 PPM to 12.8 PPM.

Bonemeal supplements containing more than 5 PPM lead are of special concern to FDA because such supplements could be used as a source of calcium for young children (especially those allergic to milk, a major source of calcium) and by pregnant and nursing women. Fetuses, infants and children are the groups most susceptible to lead toxicity. Bonemeal products may also be used as a calcium source by older children and adults, particularly women 50 years of age and older who may require additional calcium.

A 10 gram daily dose of bonemeal (about 3 teaspoonsful), containing 5 PPM of lead will result in an intake of 50 micrograms of lead, or about half the acceptable maximum daily intake of lead from all sources, for infants and young children. The FDA acceptable maximum daily intake of lead from all sources is 100 micrograms for infants, and 150 micrograms for children between six months and two years. FDA is also concerned with the potential overuse of bonemeal products by individuals who may double or triple the dosage recommended on the label, thus greatly increasing their exposure to lead.

Meanwhile FDA advises that bonemeal be used "as little as possible" in diets of infants, young children, and pregnant or nursing women because of the unknown but often substantial amounts of lead found in individual bonemeal samples. The information was addressed to physicians and other health professionals in the April 1982 issue of the FDA Drug Bulletin.

Veterinary and Human Toxicology, Vol. 24/No. 4, August 1982.

(Author's Note: The Gypsy Moth threat to California timber has made this article timely despite its date of publication.)

V.Rash Illness Associated with Gypsy Moth Caterpillars- Pennsylvania

Between the end of April and the third week of May 1981, an increase in rash illness was reported by 2 schools in Luzerne County, in northeast Pennsylvania. School A had an enrollment of 320 students, with 135 affected by rashes (an attack rate of 42.2%). School B had 76 out of 300 students affected (an attack rate of 25.3%). The symptoms included pruritic (itchy) rash and occasional urticaria (hives). Fever, nausea, vomiting, diarrhea, and chills were seldom reported. The rash was generally located on exposed areas of the body - 75.4% on arms, 22.8% on the neck, and 21.1% on legs. Rash was less often observed on the back, stomach, face, chest, or hands. The median duration of the rash for school A was 7 days, and for school B, 4 days. All skin scrapings of the rash for bacteria were negative; throat and stool cultures, and tests of acute- and convalescent-phase serum specimens to detect viruses were also negative.

A group of well students from the same schools were selected as controls. All students were interviewed for history of outdoor exposure. Touching caterpillars (p <0.01), working in a garden (p <0.05), and going fishing (p <0.01) were statistically associated with rash illness, whereas a history of allergies was not.

Of the cases with known dates of onset, 27.5% occurred during the first week of May. This period coincides with the first larval instar of gypsy moth caterpillars, which occurs between the first and fourth weeks of May in this area. No new cases were reported after the third week of May. School A is located in a heavily wooded rural area, and school B in a small town with many trees. A distribution map of gypsy moth location indicates highest concentration in the areas in which these schools are located.

The temporal and geographic association between the outbreak of rash illness and the prevalence of gypsy moth larvae suggest a causal relationship may exist.

Editorial Note: Skin diseases resulting from contact with members of the Order Lepidoptera were described in ancient Greek medical writings. In 1901, several U.S. patients were reported to have experienced dermatitis following contact with Euproctis chrysorrha (brown-tailed moth) larvae. Several outbreaks of dermatitis caused by Lepidoptera have been reported; the largest outbreak involved 600 cases among 6,000 soldiers in Israel. Clinical symptoms and signs are quite variable depending on the type of insect and its stage of development when encountered, the intensity and duration of exposure, the pathogenetic mechanism involved, and the susceptibility of the host. Disease is usually caused by direct contact with the insect or its parts, but indirect contact and airborne transmission have been documented. At least 3 pathogenetic mechanisms have been described:

1) intracutaneous injection of toxic substance(s) through hollow appendages (setae) of the insect,

2) direct irritant effects of insect hairs or appendages, and

3) hypersensitivity reaction to insect antigen. A biphasic reaction to skin testing with insect antigens has been described among some patients, which may represent sequential occurrence of 2 or more of these mechanisms .

The gypsy moth (Lymantria dispar) is a serious threat to hardwood trees in the northeastern United States . It was introduced into the Boston area in 1869 and has been spreading concentrically. Despite heavy infestation in the Northeast, skin diseases have seldom been attributed to the insect except in special laboratories where staff work with the moth and its larvae. No community outbreaks had been reported before 1981, when outbreaks of skin disease attributed to the gypsy moth were reported from Connecticut, Massachusetts , Rhode Island , and Pennsylvania. These outbreaks are believed to have been caused by contact with early larval stages of the moth, which are highly mobile and airborne. It is also possible that the disease is caused by a chemical substance that the larvae acquire during pest control programs. Primary-care physicians and dermatologists should be aware of skin disease resulting from contact with gypsy moth larvae.

MMWR, Vol.31/No.13,April 9, 1982

VI.Employee Illness From Underground Gas and Oil Contamination - Idaho

The National Institute for Occupational Safety and Health (NIOSH) recently completed an evaluation of an office building in Boise, Idaho, in which workers were experiencing symptoms of headache and nausea related to intermittent noxious odors. The cause of the problem was gasoline vapors entering the building from an underground aquifer contaminated with petroleum products leaking from a nearby oil storage tank.

The affected employees worked in the basement of a five-story medical office building and had been experiencing the symptoms - which in one case included vomiting - intermittently for 10 months. The symptoms were occasionally associated with a petroleum odor that the NIOSH investigator found coming through cracks in the floor and the joints at which the floor met the foundation and the support pillars connected to the floor. Laboratory analysis confirmed the source of the odor as gasoline. The vapor concentrations at the cracks and inside one wall were above the lower explosive limit for gasoline of 14,000 ppm, and the vapor concentrations in the rooms ranged up to 280 ppm.

EDITORIAL NOTE: The employees' symptoms are consistent with the gasoline vapor concentrations found in the building and with the higher concentrations that probably existed intermittently in the past.

NIOSH has evaluated or is currently evaluating over 100 complaints of various symptoms among office employees. Although a large majority of these evaluations have found that the complaints derive from inadequate office ventilation, occasionally symptoms can be linked to substances measured in the environment, e.g., fibrous glass, fumes from spirit duplicators, and emissions from urea-formaldehyde foam insulation. In the Idaho situation, prompt correction was required to prevent a possible explosion of gasoline vapors. Although such situations are unusual, building occupants in areas near petroleum storage facilities (including gasoline service stations) should be alert to the possibility of environmental contamination - particularly of the water table by petroleum products.

MMWR, Vol. 31/No. 33, August 27, 1982.

VII.Residue Avoidance Program: USDA Extension Service

Dr. Ben Norman of Veterinary Extension and I are working together on a poject funded by USDA Extension to conduct a program aimed at preventing chemical residues in edible tissues from food animals. This project was initiated by the Food Safety and Inspection Service (FSIS) to improve upon an already excellent record of wholesome meat production by meat producers. Every year producers lose hundreds of thousands of dollars due to condemnation of carcasses because they contain levels of chemicals (usually antibiotics) which exceed federal tolerance levels. The excessive residues in tissues are almost always due to factors that could be prevented. FSIS would like to prevent these losses and turned to the Extension Service because of our effectiveness in education and our good relationship with producers. We will be developing a program using microcomputers and visual aids that will help to educate cattle producers about the proper use of antibiotics for various diseases, with the aim to reduce carcass contamination and monetary loss caused by improper use practices.