Polycylic Aromatic Hydrocarbons: Goals for Site Remediation
Current remediation goals for PAHs in soils are either risk based or based on limits of detection.
LaGoy and Quirk
(p. 348) suggest that because natural background concentrations of PAHs are often greater than these criteria and PAHs are a generic contaminant in waste sites, present standards for remediation are sometimes impractical. The authors propose new criteria for cleanup of PAHs that are achievable and practical.
Arsenic Risk Assessment
Carlson-Lynch et al.
(p. 354) question the validity of the current EPA risk assessment for arsenic, suggesting that values should not be based on linear dose-response relationships nor on incidences of internal cancers. The authors object to evaluations of risk that ignore proposed detoxification mechanisms for arsenic and to risk estimates derived from Taiwan epidemiological studies that may be confounded by environmental contaminants other than arsenic.
Environmental Legislation '94
Prominent groups in industry and the environmental community are lobbying Congress to favorably address a number of key environmental issues up for vote (p. 366). The year 1994 is filled with proposed environmental legislation, including Superfund reauthorization, reenactment of the Clean Water Act, elevation of the EPA to cabinet status, various issues that turn on risk assessment, reauthorization of the Endangered Species Act, reforms on pesticide regulations, reformation of the 1872 Mining Law, and strengthening of the Safe Drinking Water Act. The Clinton administration has prepared plans to try to insure that the bills can move through Congress without undue crippling amendments.
Clinton's Scorecard
If he doesn't hook it into the rough or slice it into the pond, Clinton can break par in 1994, judging by the scores entered by the League of Conservation Voters (p. 370). The first hole was a short par 4 that was easily birdied, when more environmentalists were appointed to key governmental posts than ever before. From his number one teammate, Al Gore, to Kathleen McGinty, named head of the new Office of Environmental Policy, Clinton filled his staff with individuals praised by environmentalists. Poor shot selection led to a double bogey on the important fifth hole, when the president failed to back up environmental rhetoric with financial commitments. Later on the dogleg seventh hole, Clinton picked up another par when he signed the Biodiversity Treaty, created a National Biological Survey, and addressed a host of other environmental issues. On the tough home hole Clinton managed a bogey when he was advised by the Sierra Club to pick issues worth fighting for and refuse to compromise on those selected.
Cell Phospholipid Reduces Silica Lung Toxicity
Exposure to silica particles causes inflammation, damaged respiratory epithelium and interstitial matrix, and fibrosis of the lungs.
Antonini et al.
(p. 372) demonstrated that prior treatment of rats with amiodarone reduced pulmonary damage caused by subsequent exposure to silica, as shown by biochemical tests of bronchoalveolar lavage fluid. The mechanism of the drug's action may be be related to changes in phospholipid metabolism, including elevated extracellular phospholipids combined with inhibition of pulmonary phospholipases. The efficacy of amiodarone is only proven for acute silica exposure, and reduction of the initial pneumotoxic response to silica may not affect the eventual development of fibrosis.
Pesticides Screened for Estrogenicity in Cultured Breast Cells
Soto et al.
(p. 380) exposed human breast estrogen-sensitive cells to the organochlorine pesticides toxaphene, dieldrin, and endosulfan
in vitro
and found they each had estrogenlike activity. The test compares the minimal dose of estradiol needed to maximize cell proliferation with that of test compounds, so that the ratio of the values can be calculated. The potency of the tested pesticides were comparable with that of two known estrogenic pesticides, DDT and kepone. Data from the study also suggested that estrogenic chemicals may act cumulatively when present at subthreshold doses.
Lead Exposure in Mexico City
Because Mexico ranks sixth in lead production and uses 40% of the product locally, low-level lead exposure is prevalent.
Romieu et al.
(p. 384) cite major sources of lead pollution that include gasoline emissions, ceramics, paint, and food and drink containers. Lead in the environment is reflected by elevated blood lead levels in the population, showing that chronic lead exposure is an ongoing problem in need of remediation and regulation.
Environmental Risk Factors for Osteoporosis
A conference held at NIEHS reviewed the present state of knowledge of risk factors for osteoporosis, focusing on environmental agents (p. 390). The experts agreed it was reasonable to conclude there was a potential link between lead exposure and osteoporosis, based on evidence from human and animal studies showing that lead adversely affected endocrine regulation of bone mineral homeostasis. Cadmium was also believed to constitute a risk factor for osteoporosis, judging from epidemiology studies that demonstrated kidney dysfunction resulting from cadmium exposure. Although the experts could not describe a clear relationship between aluminum and osteoporosis, they did not rule out the possibility of an unknown association since patients with aluminum deposition in bone usually also display some type of bone disease. The scientists concluded that there was no association between fluoride in drinking water and increases in bone fractures, and to the contrary, advised that fluoride intake of 50-80 mg/day may decrease fractures. The importance of dietary minerals was stated, but it was emphasized that mineral supplementation cannot completely offset other dietary deficiencies or changes in endocrine status that sometimes occur during the postmenopausal period.
Last Update: August 14, 1998