In the first case study, high levels of dioxin in fish downstream of pulp and paper
mills were inadvertently detected in 1983 as part of an EPA effort to determine
background levels of dioxin in areas presumed to be relatively uncontaminated.
These findings quickly got the release of dioxins from pulp and paper mills on
EPA’s
research
agenda. News reports beginning in 1987 elevated the issue onto the
regulatory
agenda, but more than a decade has passed without EPA taking final
regulatory action. Meanwhile, the pulp and paper industry has dramatically
reduced, but not eliminated, dioxin discharges from mills.
Pada kasus pertama, level yang tinggi dari dioksin pada ikan di hilir dari pulp and
paper mills telah di deteksi dengan hati-hati pada tahun 1983 sebagai usaha EPA
untuk menentukan latar belakang level dari dioksin di area terduga menjadi tidak
terkontaminasi (bersih) secara reltif. Penemuan-penemuan ini dengan cepat
mendapat pembebeasan dari dioksin pulp and paper mills pada agen penelitian
EPA. Berita baru dilaporan pada tahun 1987 mangangakat issue tersebut ke dalam
agenda umum, tetapi lebih dari satu dekade telah berlalu tanpa ada akhir regulasi
yang di buat oleh EPA. Sementara itu, industry pulp and paper telah mengurangi
secara dramatis, tetapi tidak mengeliminasi pemebrian dioksin dari mills.
AOX is not statistically related to dioxin at the levels under
consideration. Environmentalists justify using AOX because it serves as
a surrogate measure for the entire toxicologically uncharacterized
“soup” of organocholorines discharged from bleaching mills
.AOX karena itu menyajikan sebagai langkah pengganti untuk seluruh
racun yang tidak di tandai
‘soup’
dari pemecahan organoklori dari
pemutihan kertas.
The term dioxin encompasses a family of organic chemical compounds known as dibenzo-p-dioxins. The dioxins of greatest environmental and public health concern are halogenated dioxins.1 Because they are the most common, most attention is focused on the group of 75 chlorinated dioxins. Dioxins are not deliberately manufactured, but are a byproduct of combustion, some chemical manufacturing, some bleaching of pulp and paper, and other industrial processes involving chlorine and other halogens. In the U.S., municipal and medical waste incineration are the dominant known sources of dioxin (EPA 1994a), but the total releases of dioxin from all sources (including natural sources such as forest fires) is highly uncertain. Dioxin became notorious in the 1970’s when it was
identified in the U.S. as “the most potent animal carcinogen ever tested.” As one observer phrased it, dioxin earned the reputation as the “Darth Vader” of chemicals (Roberts 1991).
In the 1980s, however, Canada and European countries set dioxin limits less stringent than EPA’s by two or three orders of magnitude. Officials in these countries concluded that a different cancer model applied to dioxin. More recently, attention has focused on the environmental and non-cancer effects of dioxin and dioxin-like substances that may mimic hormones and act as “endocrine disruptors.”
Pada tahun 1980 , Negara Kanada dan Negara-Negara di Eropa membatasi dioksin lebih ketat dari pada dua atau tiga permintaan yang besar oleh EPA. Pegawai pegawai di Negara Negara tersebut menyimpulkan bahwa perbedaan model kanker telah diaplikasikan kepada dioksin. Baru baru ini, perhatian lebih focus pada lingkungan dan efek selain kanker dari dioksin dan bahan kimia lain dari dioksin yang mungkin meniru hormone dan bertindak sebagai pengacau endokrin.
(Intinya perhatian bukan lagi terpusat pada rsiko kanker melainkan kepada lingkungan dan efek kesehatan lain selain kanker)
Over time, the list of toxic water pollutants of concern related to chlorine pulp bleaching was broadened to include a variety of more abundant chlorinated organic compounds (organochlorines). These include polychlorinated phenolic compounds, which are considered representative of a various polychlorinated organic materials that may accumulate in food chains, and chloroform, a volatile organic compound.
Dalam watu lebih, daftar dari konsentrsi polutan air terkait dengan pemutih (klorin) pada pulp, meluas termasuk kandungan jenis klorin organic yang sangat banyak. Ini termasuk kandungan phenol poliklorin yang mewakili dari jenis-jenis material poliklorin organic yang mungkin terakumilasi di rantai makanan, chloroform dan kandungan organic yang menguap.
Melalui usulan regulasi effluent pulp and paper pada tahuan 1993, EPA mencari pendahuluan batas pada rumus dioksin, furan dan organoklorin lainnya pada proses manufaktur pulp and paper.
As Finkel (1988) noted, our national preoccupation with dioxin stems largely from the notoriety of TCDD as the most potent animal carcinogen ever tested, and its ubiquity as a contaminant of pesticides, incinerator smoke and ash, and bleached paper consumer products such as diapers and coffee filters. More recently, the dioxin story has segued into the broader debate over “endocrine disruptors,” a class of hormone-like chemicals suspected of having a variety of
reproductive and other non-cancer effects.
Endocrine disruptors are the subject of the much-discussed popular science book entitled, Our Stolen Future, which argues that background levels of chlorinated organics and other industrial chemicals may play a role in development of breast cancer, falling sperm counts and other male reproductive disorders, as well as developmental effects in wildlife and humans (Colborn et al. 1996).12
Sesuai catatan Finkel (1988), Keasyikan nasional kita kepada dampak karsinogen pada hewan dari dioksin dan menjadi kontaminan pada perstisida yang ada dimana mana, asap insenerator dan abu dan prodak pemutih dan penyaring kopi. Baru-baru ini, dioksin menjadi perdebatan lebih luas sebagai perusak endokrin pada hormone seperti jenis kimia yang dicurigai mengandung dioksin dan efek lain selain kanker dari dioksin.Finkel, A. 1988. “Dioxin: Are We Safer Now than Before?,” Risk Analysis, Vol. 8, No. 2, pp. 161-165.
Perusak endokrin adalah topic yang paling popular yang sedang didiskusikan dala buku yang berjudul Our Stolen Future,yang menentang tingkat latar belakang dari klorin organic dan industry kimia lainnya yg mungkin memainkan peran dalam perkembangan kanker payudara, penururnan jumlah sperma dan penurunan fungsi organ kelamin pria sebagaimana berkembang hawan dan manusia. (Colborn et al. 1996).12 Colborn, T., D. Dumanoski, and J. Peterson Myers. 1996. Our
Stolen Future: Are We Threatening Our
In 1974, the federal Centers for Disease Control (CDC) identified dioxin as a toxic substance in Missouri waste oil. In 1982, EPA detected high dioxin levels from TCDDcontaminated oil sprayed on streets in Times Beach, MO, and dioxin was implicated in illnesses in horses and possibly children.
Pada tahun 1974 federal Centers For Disease Contorl (CDC) mengidentifikasi dioksin sebagai racun kimia pada limbah minyak Missouri. Pada thun 1982 EPA mendeteksi terdapat level dioksin yang tinggi dalam bentuk kontaminan TCDD pada spray (semprot) minyak yang terbuang ke laut, MO, dan dioksin telah menyebabkan penyakit pada kuda-kuda dan mungkin pada anak-anak.
Cancer Assessment Group derived an extraordinarily high cancer potency factor (4.25 x 105 (mg/kg/day)-1) for dioxin in 1981. An important basis of this estimate was a reanalysis of the pathological evidence from the Dow Chemical researchers’ rat study (Kociba et al. 1978) performed by Robert Squire of Johns Hopkins University Medical School.17
Kociba, R. D. Keyes, J. Beyer, et al. 1978. “Results of a Two Year Chronic Toxicity and Oncogenicity Study of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin in Rats,” Toxicology and Applied Pharmacology, Vol. 46, pp. 279-303.
Kelompok Penaksiran kanker mendapatkan factor potensi kanker yang luar biasa (4.25 x 105 (mg/kg/day)-1) untuk dioxin pada tahun 1981. Tetapi hal ini di analisa kembali.
Sumber
Control of Dioxins (and other Organochlorines) from the Pulp and
Paper Industry under the Clean Water Act and Lead in Soil at Superfund
Mining Sites: Two Case Studies in EPA's Use of Science
( terkait dengan table TDI)
Although it concluded that TCDD is most likely a cancer promoter and not a cancer initiator, the US EPA assumes no threshold for TCDD effects, and employs a linear dose-response model. Several members of the Science Advisory Board (SAB) charged with reviewing the draft were critical of this decision, seeing no biological foundation for treating cancer effects any differently than noncancer effects (US EPA 2001, p.37-8). In addition, use of conservative assumptions beyond normal agency practice and exclusion of selected epidemiological cohorts have raised significant concerns over EPA.s risk analysis.
Walaupun table tersebut menyimpulkan bahwa TCDD sebagai penyebab kanker dan pemrakarsa kanker, EP berasumsi no threshold for TCDD effects, menggunakan model respon dosis linier. Beberapa kelompok dari Science Advisory Board (SAB) membebankan dengan meninjau ulang draft yang ada dengan memberi kritik pada kesimpulan ini, tindakan ini tanpa melihat dasar biological untuk perlakuan pada efek kanker secar berbeda daripada yang tidak member efek kanker (US EPA 2001, p.37-8). Lebih lanjut, menggunakan asumsi konsefatif melewati agen praktis normal, dan pengeluaran kelompok epidemiological terpilih telah naik secr signifikan menjadi konsen EPA untuk resiko analisis.
