PUBLIC HEALTH ASSESSMENT
TUCSON INTERNATIONAL AIRPORT AREA
a/k/a EL VADO RESIDENTIAL PROPERTIES
TUCSON, PIMA COUNTY, ARIZONA
Dermal and ocular effects in the form of chloracne, skin rashes, and eye irritation have been observed with occupational inhalation exposure to Aroclors. Chloracne is a distinctive acneform eruption manifested by keratinous plugs called comedones and skin-colored cysts. Mild to moderate chloracne was seen in seven of 14 workers exposed to 0.1 mg/m3 of Aroclors for an average period of 14.3 months. However, PCBs were not the only substance to which workers were exposed. Workers receiving exposures at levels as low as 0.003 mg/m3 for >5 years had dermal effects which included rashes, pigmentation changes of the skin and nails, and other skin changes. Eye irritations have also been documented with airborne PCB exposure. In these studies, workers received exposure to various Aroclors at concentrations between 0 and 2.2 mg/m3 for >3 years.
Human health effects have been documented more frequently for inhalation exposure to PCBs than for ingestion and dermal exposures. Respiratory symptoms have been reported for inhalation exposures to Aroclor-exposed workers. Upper respiratory tract or eye irritation, cough, and tightness of the chest were documented for 326 capacitor workers with inhalation exposure levels of 0.007-11 mg/m3. Limitations of the study included the absence of a control group, poor definition of cohort, and other factors. Of 243 workers involved in the above study, 14% demonstrated a decline in forced vital capacity (FVC) when compared to the standard values. Of those with a decline in FVC, 80% manifested a restrictive pattern of impairment without radiologic changes. There is limited evidence of neurological effects from inhalation exposure. In one study, almost half of the workers at a capacitor plant receiving exposure to mean concentrations of Aroclors at 0.007-11 mg/m3 for five years complained of headache, dizziness, depression, fatigue, and nervousness. In addition, switchgear workers exposed to Aroclor 1260 and 1242 at concentrations of 0.00001-0.012 mg/m3 had a higher incidence of headaches and problems with memory and sleeping compared to unexposed workers.
Neurological effects have been seen in humans but, particularly, in animals with oral exposure to PCB. Farm families who ate dairy products and beef contaminated with PCBs had a 19% prevalence of numbness. Because of the subjectivity of symptoms and the lack of controls, no definitive association could be shown between PCB exposure and the neurological effect. In animals, doses between 0.8 and 3.2 mg/kg-day of Aroclor 1016 in the diet for 20 weeks did not influence the concentrations of noradrenaline, adrenaline, or serotonin in monkey brains. In addition, no histological changes were reported in the brains of rats administered 100 mg/kg-day of Aroclor 1242 by gavage every second day for three weeks. Changes in the neurotransmitter serotonin were documented in several areas of the brain when rats received a mixture of Aroclor 1254 and 1260 at single, high doses of 500 and 1,000 mg/kg.
Animal studies have shown that PCBs containing 60% chlorine by weight are carcinogenic. At an estimated dose of 5 mg/kg-day, Aroclor 1260, fed to female Sherman rats, resulted in the formation of hepatocellular carcinomas. Sprague-Dawley rats formed liver tumors after receiving an estimated 3.45 mg/kg-day of Aroclor 1260 in their diet for 24 months. In a National Cancer Institute study, no treatment-related liver tumors
manifested in Fisher-344 rats receiving estimated doses of 1.25, 2.5 or 5.0 mg/kg-day dietary Aroclor 1254 for 104-105 weeks. However, nonhepatic tumors (i.e. adenocarcinoma of the stomach, jejunum, or cecum) were positively associated to the Aroclor 1254 treatment in male and female rats.
Cancer effects have been seen in workers exposed to PCBs by inhalation. The studies have had limitations resulting in no definitive statement regarding PCB's cancer-causing effects. In one study, an excess risk for cancers of the liver, biliary tract, or gall bladder was detected in 2,588 workers employed in two capacitor factories. The workers had been employed between 1940 and 1976, at least three months, in areas with the most exposure to PCBs. Aroclor 1254 was initially used, then Aroclor 1242 and finally Aroclor 1016. Personal time-weighted average concentrations of Aroclor 1016 in 1977 were 0.024 to 0.393 mg/m3 at Plant 1 and 0.170 to 1.26 mg/m3 at Plant 2. There were three cases of liver, gallbladder, and/or biliary tract cancer as compared to 1.07 expected, and four cases of rectal cancer as compared to 1.19 expected. One of the study's limitations was the small number of cases. In another study, increased mortality due to cancer was found in 544 male and 1,556 female workers of a capacitor manufacturing plant in Italy. The workers had been employed between 1946 and 1978 for at least one week. PCB mixtures containing 54% chlorine were in use until 1964 and eventually mixtures of 42% chlorine were in use until 1970. Area samples obtained in 1954 and 1977 revealed PCB air levels of 5.2 to 6.8 mg/m3 (54% chlorine) and 0.048 to 0.275 mg/m3 (42% chlorine). Among the findings, deaths from all cancers in males were significantly greater than expected when contrasted to national and local rates (14 observed versus 1.7 national and 2.2 local), and in females contrasted with local rates (12 observed versus 5.3 expected). A significantly higher death rate from gastrointestinal tract cancer was seen in males when contrasted to national and local rates. The study's limitation involved the small number of cases, short minimum exposure, and other factors. In addition, a mortality study of 3,643 workers of a capacitor manufacturing facility revealed some indication of PCB exposure-related malignant melanoma. The mean duration of employment was 4.1 years, while the mean age at hire was 27 years. PCB had been utilized from 1957 - 1977, and this was the period in which the workers had been employed. Aroclor 1242 was utilized until 1970, followed by Aroclor 1016. Area monitoring in 1977 detected mean concentrations of PCBs ranging from 16 to 76 g/m3. The workers were also exposed to various other chemicals. A statistically-significant difference was seen for malignant melanoma when the observed cases (8) were contrasted to the expected number of cases (2). The study had a number of limitations, which included the small number of deaths, insufficient monitoring data and other factors.