David F. Goldsmith

Assessment of azinphosmethyl exposure in California peach harvest workers

We compared measurements of urinary alkylphosphate metabolites and oxime-induced reactivation of plasma cholinesterase (P-ChE) and erythrocyte acetylcholinesterase (RBC-AChE) with measurements of foliar residues, skin and clothing contamination, and P-ChE and RBC-AChE activities among 20 Northern California peach orchard workers exposed to the organophosphate agent azinphosmethyl (Guthion). Subjects entered orchards treated 30 d previously with azinphosmethyl and worked 21 d in treated fields during the ensuing 6 wk. Dislodgeable foliar residues ranged from 0.32-0.96 micrograms/cm2. Median reduction in RBC-AChE activity was 7% (p < .001) over the initial 3-d period of exposure and 19% (p < .01) over the 6-wk season. Urinary metabolites were the most sensitive indicator of recent exposure and correlated moderately with dermal and clothing levels (rs = +0.31-(+)0.55); urinary metabolites correlated well with RBC-AChE drawn 3 d after exposure began (rs = -0.77). No significant oxime-induced reactivation was found.

A case-control study of prostate cancer within a cohort of rubber and tire workers.

A matched case-control study was conducted to test the hypothesis that prostate cancer is associated with employment in the compounding area of a rubber and tire manufacturing plant. A search of death certificates from the years 1964 to 1975 led to the identification of 88 cases of prostate cancer. These were individually matched with 258 controls on the factors of age, race, and date of entry into the plant. To eliminate possible confounding by sociodemographic differences, several variables were assessed but none differed significantly between cases and controls. The batch preparation work area showed statistically significant (p < 0.025) risk ratios over three exposure periods -- more than one month, more than 24 months, and more than 60 months. The service to batch preparation and shipping and receiving work areas showed significant risks for blacks. The data were used to assess a latent period or etilogic fraction for prostate cancer for those employed in batch preparation. Twenty-nine years was estimated to be the latent period while the period of greatest risk occurred during the years 1940 to 1947.

Elevated lead in drinking water in Washington, DC, 2003-2004: the public health response.

Background In 2003, residents of the District of Columbia (DC) experienced an abrupt rise in lead levels in drinking water, which followed a change in water-disinfection treatment in 2001 and which was attributed to consequent changes in water chemistry and corrosivity. Objectives To evaluate the public health implications of the exceedance, the DC Department of Health expanded the scope of its monitoring programs for blood lead levels in children. Methods From 3 February 2004 to 31 July 2004, 6,834 DC residents were screened to determine their blood lead levels. Results Children from 6 months to 6 years of age constituted 2,342 of those tested; 65 had blood lead levels > 10 μg/dL (the “level of concern” defined by the Centers for Disease Control and Prevention), the highest with a level of 68 μg/dL. Investigation of their homes identified environmental sources of lead exposure other than tap water as the source, when the source was identified. Most of the children with elevated blood lead levels (n = 46; 70.8%) lived in homes without lead drinking-water service lines, which is the principal source of lead in drinking water in older cities. Although residents of houses with lead service lines had higher blood lead levels on average than those in houses that did not, this relationship is confounded. Older houses that retain lead service lines usually have not been rehabilitated and are more likely to be associated with other sources of exposure, particularly lead paint. None of 96 pregnant women tested showed blood lead levels > 10 μg/dL, but two nursing mothers had blood lead levels > 10 μg/dL. Among two data sets of 107 and 71 children for whom paired blood and water lead levels could be obtained, there was no correlation (r2 = –0.03142 for the 107). Conclusions The expanded screening program developed in response to increased lead levels in water uncovered the true dimensions of a continuing problem with sources of lead in homes, specifically lead paint. This study cannot be used to correlate lead in drinking water with blood lead levels directly because it is based on an ecologic rather than individualized exposure assessment; the protocol for measuring lead was based on regulatory requirements rather than estimating individual intake; numerous interventions were introduced to mitigate the effect; exposure from drinking water is confounded with other sources of lead in older houses; and the period of potential exposure was limited and variable.

An epidemiologic study of respiratory health effects in a group of North Carolina furniture workers.

Woodworking is known to be associated with nasal cancer and with western red cedar asthma, but research is inconsistent with regard to respiratory health effects among furniture workers. The authors tested the hypotheses that employment in a North Carolina hardwood furniture plant was related to the prevalence of respiratory symptoms and to impairment of pulmonary function. Chronic symptom prevalence generally showed no significant differences between wood dust jobs and control exposures; however, frequent sneezing and eye irritation were significantly (P less than .05) correlated with wood dust exposed jobs; in both cases the prevalence odds ratio was 4.0. Peak flow was the only pulmonary function measure that correlated significantly (P = .0345) with wood dust employment. The difference in forced vital capacity suggested a weak association with current employment in finishing jobs, whereas the difference in peak flow showed a modest correlation with the fraction of particulate less than 10 microns. The relevance of the present associations to regulatory changes and research needs is discussed.

Mortality in agricultural workers after compensation claims for respiratory disease, pesticide illness, and injury

The long-term mortality experience of California agricultural workers who filed workers compensation claims for respiratory diseases, pesticide illnesses, and injuries between 1946 and 1975 was observed until 1991 and compared to U.S. death rates. The respiratory disease claimants had an elevated relative risk of 3.27 (95% CI 2.09-4.86) for mortality from nonmalignant respiratory diseases (NMRD). Emphysema mortality was particularly high, with a relative risk of 5.94 (95% CI 2.56-11.70). NMRD mortality peaked 5 to 9 years after the claims were filed (relative risk 9.83, 95% CI 4.47—18.57) and was most strongly associated with exposure to wood, rice, coffee, and flour dusts. Among the pesticide illness claimants, mortality from heart disease was slightly elevated in the subcohort with systemic pesticide illness (SMR=1.32, 95% CI 0.86-1.94). Among the injury claimants, risk was increased for motor vehicle deaths (relative risk 1.62, 95 % CI 0.74—3.08). It was concluded that respiratory disease claimants in agriculture have a significantly elevated risk of mortality from respiratory diseases and that the risk is highest (10-fold) 5–9 years after claims are filed.

Calculating cancer latency using data from a nested case-control study of prostatic cancer

Assessing latency for neoplastic diseases is crucial for determining the causal effects of a complex mix of carcinogenic exposures. An initial assessment of cancer risks in a U.S. tire and rubber plant revealed a significant SMR of 140 for prostatic cancer. Using an industry-based, case-control death certificate study of prostatic malignancies, we found matched odds ratios of about 3 (p less than 0.025) for Batch Preparation, the work area with the greatest exposure to carbon black, solvents, and heavy metal oxides. To assess latency, we used the matched case-control series to calculate annual estimates of the odds ratio by determining the proportion of cases and controls employed for greater than 1 month in Batch Preparation during each year under study. This approach produced a plot with great fluctuations. To reduce variability in the resulting curve, a method was developed that measured the etiologic fraction, which is its highest point represents an estimate of the peak of the latency distribution. For Batch Preparation the modal point was 29 years before death with the greatest risk occurring from employment in the mid-1940s. The latency method allows risk assessment for time and year of greatest exposure difference, thus suggesting appropriate prevention strategies. Applications of this method for other types of studies and exposures are discussed.

Occupational medicine in a developing society: a case study of Venezuela.

Recent activities of the World Health Organization and other international agencies have placed new emphasis on occupational health in developing nations. Venezuela is a nation in transition from a developing society dominated economically by petroleum and agriculture to an economically- diversified industrialized urban society. It provides a case study which illuminates the problems of extending occupational health services in developing economies and questions of public policy regarding utilization of medicalresources and the priority that occupational health should hold in such a society. Occupational health has become a serious problem in the developing world as new industries and accelerating economic development occur without adequate resources for worker protection. The study of cases such as that of Venezuela may provide guidance for anticipating and preventing problems in other nations. This paper should be considered a pilot study to explore a social aspect of occupational health that has not received adequate attention.