Challenges in assessing long-term health effects studies.

After almost 50 yr since modern synthetic pesticides first received wide-spread use in the USA, many of the challenges that need to be met in determining their-long term effects on human health remain unanswered. Answers to many of the key challenges, such as accurate exposure assessment, pesticides' role in multifactorial causation of disease, latency, publishing of negative results, misclassification, low-level dose measurement, accurate diagnosis, the role of biomarkers, adequate study design, and adequate funding, will continue to be key factors in investigating the role, if any, of these chemicals in the transmission of human diseases.

Termiticide use and indoor air quality in the United States.

Organochlorine insecticides have been used extensively for the past 35 yr to reduce termite damage. The USEPA estimates that chlordane and heptachlor have been used in 24 million homes in the US. The pollution of air inside dwellings is a growing concern in the US because the population at risk includes the young and aged. Those exposed to pollutants in the home may be exposed for 24 hr instead of the usual 8 hr a day in the work place. Many of the halogenated aromatic hydrocarbons have been used as pesticides and have been reported as air contaminants inside buildings. Most of these chemicals are lipophilic, ubiquitous in the environment, and persistent. A number of chemicals found in indoor air have been reported to cause human health effects and some are carcinogenic. Many studies have been conducted using a variety of air samplers inside dwellings to determine levels of termiticides in indoor air. These include the Greenburg-Smith impinger, nylon chiffon screens, polyurethane foam plug samplers, and a Millipore miniature vacuum pump with a sampling tube containing Chromosorb 102 as the collecting medium. Chlordane and heptachlor have been widely used as termiticides and both have been implicated as serious problems. The US Air Force experienced several instances of contamination of houses with airborne chlordane following termite treatment, and numerous other studies have shown the magnitude of the problem. Because of increased instances of indoor air contamination, several new alternatives have been developed for termite control to reduce the potential for chemical exposure in indoor air of houses treated with termiticides. These new techniques include use of growth regulators and newer less hazardous chemicals.

Chronic neurological sequelae of acute organophosphate pesticide poisoning.

To evaluate the latent neurological effects of organophosphate pesticide poisoning, this epidemiologic study examined 100 matched-pairs of individuals with previous acute organophosphate pesticide poisoning and nonpoisoned controls. No significant difference between poisoned subjects and controls was found on audiometric tests, ophthalmic tests, electroencephalograms, or the clinical serum and blood chemistry evaluations. Of the more than 50 scores from the neurological examination, abnormalities were demonstrated among the cases only on measures of memory, abstraction, and mood, and on one test of motor reflexes. Differences between the two cohorts were much more apparent in the neuropsychological tests. The differences occurred on tests of widely varying abilities including intellectual functioning, academic skills, abstraction and flexibility of thinking, and simple motor skills. Twice as many cases as controls (24 vs. 12) had Halstead-Reitan Battery summary scores in the range characteristic of individuals with cerebral damage or dysfunction. Results from the Minnesota Multiphasic Personality Inventory and the Patient's and Relative's Assessment of Patient Functioning Inventories also revealed greater distress and complaints of disability for the poisoned subjects.

A comparative study of pesticide exposures in adults and youth migrant field workers.

To study possible differences between pesticide exposures received by youth (subjects less than 16 yr of age) and adults (subjects greater than 16 yr of age), human exposure samples (gloves and urine) were collected during the onion harvesting season of 1982. Environmental samples (soil, foliage, and field air) were also collected during the study period. All samples were analyzed for toxaphene, ethyl parathion, methyl parathion, and malathion. Environmental samples were found to have very low levels of these insecticides. The youth cohort had lower residue values than did the adults, and these differences were statistically significant (P less than 05) for toxaphene residues on gloves on each sampling day, and for ethyl parathion residues on gloves on one sampling day only. Detectable levels of dialkyl phosphates were found in only 2 of 44 urine samples.

Household pesticide usage in the United States.

A total of 10,000 U.S. households in 25 standard metropolitan statistical areas and 25 counties were included in the United States. More than 8,200 households granted an interview. Nine of every ten households in the United States used some types of pesticide in their house, garden, or yard. Households in the southeastern United States used the most pesticides. Although more than 500 different pesticide formulations were used by the sampled households, 15 pesticides accounted for 65.5% of all pesticides reported in this study. Thirteen of these 15 pesticides were insecticides, one was a herbicide, and one was a rodenticide.

National study of chlorinated hydrocarbon insecticide residues in human milk, USA. I. Geographic distribution of dieldrin, heptachlor, heptachlor epoxide, chlordane, oxychlordane, and mirex.

Human milk samples obtained from 1436 women residing in the United States were analyzed by gas-liquid chromatography for the chlorinated hydrocarbon insecticides--dieldrin, chlordane, heptachlor, heptachlor epoxide, oxychlordane and Mirex. Dieldrin was found above the detection limit (1.0 ppb) in over 80% of all the samples collected. Chlordane was not found in any of the 1436 milk samples but its metabolite, oxychlordane, was found above the detection limit in 74% of the samples. Although heptachlor was recovered in less than 2% of the samples, its metabolite, heptachlor epoxide, was found above the detection limit in 63% of the samples. It was of considerable interest that Mirex was not positively identified in any of the samples. The proportion of samples with values above the detection limit for dieldrin, heptachlor epoxide and oxychlordane varied significantly among the five geographic regions with the southeastern United States having the highest mean residue level for each of these three contaminants. For the United States the mean fat adjusted residue levels of those samples above the detection limit were 164.2 ppb for dieldrin, 91.4 ppb for heptachlor epoxide, and 95.8 ppb for oxychlordane.

Gas-liquid chromatographic determination of organochlorine pesticides and polychlorinated biphenyls in human milk.

A method for the detection of organochlorine pesticides and polychlorinated biphenyls (PCBs) in human milk is described. The method involves quantitative extraction of human milk with acetone and hexane. The pesticide and PCB residues are extracted from the milk fat with acetonitrile (ACN) and then partitioned back into hexane by aqueous dilution of the ACN extract. The ACN partitioning is followed by cleanup with Florisil column chromatography, eluting with 6 and 15% mixtures of ethyl ether-hexane. The 6% eluate is concentrated and transferred to a silicic acid column for separation of PCBs from pesticide residues. Compounds are quantitated by gas-liquid chromatography. Recovery studies demonstrated that the procedure provides 68-103% recovery for pesticides and PCBs.

Suspected foodborne carbamate pesticide intoxications associated with ingestion of hydroponic cucumbers.

In the period April 1--15, 1977, nine residents of one Nebraska town experienced violent illnesses with short duration following ingestion of locally grown hydroponic cucumbers. Despite a thorough investigation, the etiologic agent of illness was not determined. From July 16--25, 1978, a second similar outbreak occurred in an adjacent city. Five individuals experienced illness similar to that which occurred in 1977, also following ingestion of hydroponic cucumbers grown at the same greenhouse involved in the 1977 outbreak. The carbamate insecticide, aldicarb, was detected in some cucumbers grown at the hydroponic greenhouse. The source of this chemical in the greenhouse could not be determined.