ESTIMATION OF INDIVIDUAL DERMAL AND RESPIRATORY UPTAKE OF POLYCYCLIC AROMATIC-HYDROCARBONS IN 12 COKE-OVEN WORKERS

Twelve workers from a coke plant in The Netherlands participated in an intensive skin monitoring programme combined with personal air sampli ng and biological monitoring during five consecutive eight hour worksh ifts. The purpose of the study was to make a quantitative assessment o f both the dermal and respiratory intake of polycyclic aromatic hydroc arbons (PAHs). Pyrene was used as a marker compound for both dermal an d respiratory exposure to PAHs. The biological measure for the interna l exposure to PAHs was urinary 1-OH-pyrene concentration. Measurements on exposure pads at six skin sites showed that mean total skin contam ination of the 12 workers ranged between 21 and 166 mug pyrene a day. The dermal uptake of pyrene ranged between 4 and 34 mug/day, which was about 20% of the pyrene contamination on skin. The mean concentration of total pyrene in the breathing zone air of the 12 coke oven workers ranged from 0.1 to 5.4 mug/m3. The mean respiratory uptake of pyrene varied between 0.5 and 32.2 mug/day. Based on the estimates of the der mal and respiratory pyrene uptake it is concluded that an average 75% (range 28%-95%, n = 12) of the total absorbed amount of pyrene enters the body through the skin. Because of the difference in the pyrene:ben zo(a)pyrene ratio between the air samples and the skin contamination s amples, the dermal uptake of benzo(a)pyrene was also estimated. This w as about 51% of the total absorbed amount (range 8%-92%, n = 12). The total excreted amount of urinary 1-OH-pyrene as a result of exposure t o PAHs during the five consecutive workshifts varied between 36 and 23 9 nmol. A multiple regression model of the mass balance between pyrene dose (both dermal and respiratory) and 1-OH-pyrene excretion confirme d the relevance of the dermal exposure route. The variation in urinary 1-OH-pyrene excretion was determined more by the dermal pyrene dose t han by the respiratory dose. The model showed an estimate of the perce ntage of the absorbed amount of pyrene that is metabolised and excrete d as 1-OH-pyrene in urine. For the 12 workers this percentage varied b etween 13% and 49% depending on smoking habits and consumption of alco hol. The results of this study indicate that among coke oven workers, the skin is the main route of uptake of PAHs. Preventive measures to r educe exposure to PAHs should be focused more on the reduction of derm al contamination by PAHs than on the reduction of inhaled dose.